<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Ranolazine and can you explain it in depth? [/INST] Ranolazine, sold under the brand name Ranexa among others, is a medication used to treat heart related chest pain. Typically it is used together with other medications when those are insufficient. Benefits appear smaller in women than men. It is taken by mouth.Common side effects include constipation, headache, nausea, and dizziness. Serious side effects may include QT prolongation. Use is not recommended in those with liver cirrhosis. How it works is not clear but may involve adenosine triphosphate.Ranolazine was approved for medical use in the United States in 2006. In 2019, it was the 211th most commonly prescribed medication in the United States, with more than 2 million prescriptions.

Medical uses
Ranolazine is used to treat chronic angina. It may be used concomitantly with β blockers, nitrates, calcium channel blockers, antiplatelet therapy, lipid-lowering therapy, ACE inhibitors, and angiotensin receptor blockers. It is also effective at preventing atrial fibrillation, and has been studied as monotherapy as well as in combination with other medications used to treat irregular heartbeat.Its use is not recommended in Scotland as of 2019.

Contraindications
Some contraindications for ranolazine are related to its metabolism and are described under Drug Interactions. Additionally, in clinical trials ranolazine slightly increased QT interval in some patients and the FDA label contains a warning for doctors to beware of this effect in their patients. The drugs effect on the QT interval is increased in the setting of liver dysfunction; thus it is contraindicated in persons with mild to severe liver disease.

Side effects
The most common side effects are dizziness (11.5%) and constipation (10.9%).  Other side effects include headache and nausea.

Drug interactions
Ranolazine is metabolized mainly by the CYP3A enzyme. It also inhibits another metabolizing enzyme, cytochrome CYP2D6. For this reason, the doses of ranolazine and drugs that interact with those enzymes need to be adjusted when they are used by the same patient.
Ranolazine should not be used with drugs such as ketoconazole, clarithromycin, and nelfinavir that strongly inhibit CYP3A, nor with drugs that activate CYP3A, such as rifampin and phenobarbital.For drugs that are moderate CYP3A inhibitors, such as diltiazem, verapamil, and erythromycin, the dose of ranolazine should be reduced.Drugs that are metabolized by CYP2D6, such as tricyclic antidepressants, may need to be given at reduced doses when administered with ranolazine.

Mechanism of action
Ranolazine inhibits persistent or late inward sodium current (INa) in heart muscle in a variety of voltage-gated sodium channels.  Inhibiting that current leads to reductions in intracellular calcium levels.  This in turn leads to reduced tension in the heart wall, leading to reduced oxygen requirements for the muscle. The QT prolongation effect of ranolazine on the surface electrocardiogram is the result of inhibition of IKr, which prolongs the ventricular action potential. Ranolazine also exhibits its effects on the delayed rectifier current (hERG/IKr potassium channels), it readily stimulates myogenesis, it reduces a pro-oxidant inflammation/oxidative condition, and activates the calcium signaling pathway.Ranolazine prolongs the action potential duration, with corresponding QT interval prolongation on electrocardiography, blocks the INa current, and prevents calcium overload caused by the hyperactive INa current, thus it stabilizes the membrane and reducing excitability.

History
Syntex Inc. originally began developing ranolazine in 1985 and 61 studies were completed from then until 1994. Afterwards, Phase 2 studies were done however it was found that the formulation did not result in adequate plasma concentrations of drug </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Ivacaftor and can you explain it in depth? [/INST] Ivacaftor is a medication used to treat cystic fibrosis in people with certain mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene (primarily the G551D mutation), who account for 4–5% cases of cystic fibrosis. It is also included in combination medications, lumacaftor/ivacaftor, tezacaftor/ivacaftor, and elexacaftor/tezacaftor/ivacaftor which are used to treat people with cystic fibrosis.Ivacaftor was developed by Vertex Pharmaceuticals in conjunction with the Cystic Fibrosis Foundation and is the first medication that treats the underlying cause rather than the symptoms of the disease. It was approved by the U.S. Food and Drug Administration (FDA) in January 2012. It is one of the most expensive drugs, costing over US$300,000 per year, which has led to criticism of the high cost. The combination drug lumacaftor/ivacaftor was approved by the FDA in July 2015.Cystic fibrosis is caused by any one of several defects in the CFTR protein, which regulates fluid flow within cells and affects the components of sweat, digestive fluids, and mucus. One such defect is the G551D mutation, in which the amino acid glycine (G) in position 551 is replaced with aspartic acid (D).  G551D is characterized by a dysfunctional CFTR protein on the cell surface.  In the case of G551D, the protein is trafficked to the correct area, the epithelial cell surface, but once there the protein  cannot transport chloride through the channel. Ivacaftor, a CFTR potentiator, improves the transport of chloride through the ion channel by binding to the channels directly to induce a non-conventional mode of gating which in turn increases the probability that the channel is open.

Medical uses
Ivacaftor is used for the treatment of cystic fibrosis in people having one of several specific mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) protein: E56K, G178R, S549R, K1060T, G1244E, P67L, E193K, G551D, A1067T, S1251N, R74W, L206W, G551S, G1069R, S1255P, D110E, R347H, D579G, R1070Q, D1270N, D110H, R352Q, S945L, R1070W, G1349D, R117C, A455E, S977F, F1074L, R117H, S549N, F1052V, D1152H.Ivacaftor is also included in a combination product, lumacaftor/ivacaftor, in a single pill, which is used to treat people with cystic fibrosis who have the F508del mutation in CFTR.Ivacaftor is also included in the combination product tezacaftor/ivacaftor with ivacaftor sold as Symdeko and as Symkevi.Symdeko is indicated to treat people aged six and older who have two copies of the F508del mutation in CFTR.Symkevi is indicated in a combination regimen with ivacaftor 150 mg tablets for the treatment of people with cystic fibrosis (CF) aged twelve years and older who are homozygous for the F508del mutation or who are heterozygous for the F508del mutation and have one of the following mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene: P67L, R117C, L206W, R352Q, A455E, D579G, 711+3A→G, S945L, S977F, R1070W, D1152H, 2789+5G→A, 3272 26A→G, and 3849+10kbC→T.Ivacaftor is available in a combination product with elexacaftor and tezacaftor called Trikafta for the treatment of people with cystic fibrosis who have the F508del mutation or other mutations.

Adverse effects
The most common adverse reactions experienced by patients who received ivacaftor in the pooled placebo-controlled Phase III studies were abdominal pain (15.6% versus 12.5% on placebo), diarrhoea (12.8% versus 9.6% on placebo), dizziness (9.2% versus 1.0% on placebo), rash (12.8% versus 6.7% on placebo), upper respiratory tract reactions (including upper respiratory tract infection, nasal congestion, pharyngeal erythema, oropharyngeal pain, rhinitis, sinus congestion, and nasopharyngitis) (63.3% versus 50.0% on placebo), headache (23.9% versus 16.3% on placebo) and bacteria in sputum (7.3% versus 3.8% on placebo). One patient in the ivacaftor group reported a serious adverse reaction: abdominal pain.

Pharmacology
Pharmacodynamics
Ivacaftor is a "potentiator" of CFTR, meaning it increases the probability that the defective channel will be open and allow chloride ions pass through the channel pore.

Pharmacokinetics
Distribution
Ivacaftor is approximately 99% bound to plasma proteins, primarily to alpha 1-acid glycoprotein and albumin. Ivacaftor does not bind to human red blood cells.

Biotransformation
Ivacaftor is extensively metabolised in humans. In vitro and in vivo data indicate that ivacaftor is primarily metabolised by CYP3A. M1 and M6 are the two major metabolites of ivacaftor in humans. M1 has approximately one-sixth the potency of ivacaftor and is considered pharmacologically active. M6 has less than one-fiftieth the potency of ivacaftor and is not considered pharmacologically active.

Elimination
Following oral administration, the majority of ivacaftor (87.8%) is eliminated in the faeces after metabolic conversion. The major metabolites M1 and M6 accounted for approximately 65% of total dose eliminated with 22% as M1 and 43% as M6. There was negligible urinary excretion of ivacaftor as unchanged parent. The apparent terminal half-life was approximately 12 hours following a single dose in the fed state. The apparent clearance (CL/F) of ivacaftor was similar for healthy subjects and patients with CF. The mean (±SD) of CL/F for the 150 mg dose was 17.3 (8.4) L/h in healthy subjects at steady state.

Society and culture
Legal status
The U.S. Food and Drug Administration (FDA) approved ivacaftor in January 2012, and soon afterwards so too did the European Medicines Agency (EMA) and Canada and across some European countries.Lumacaftor/ivacaftor was approved by the FDA in July 2015, under breakthrough therapy status and under a priority review.

Economics
The cost of ivacaftor is US$311,000 per year, roughly similar to the price of other medications for extremely rare diseases.  In the first nine months of its second year on the market (2014), ivacaftor sales were $339M, representing 54% of Vertexs product sales revenue.  During the same period, total drug development expenses were $458M, most of which was spent on cystic fibrosis-related research.An editorial in JAMA called the price of ivacaftor "exorbitant", citing the support by the Cystic Fibrosis Foundation in its development and the contribution made by fundamental scientific research performed by the National Institutes of Health and relied upon by Vertex in its cystic fibrosis drug discovery programs. The company responded in an email that "while publicly funded academic research provided important early understanding of the cause of cystic fibrosis, it took Vertex scientists 14 years of their own research, funded mostly by the company, before the drug won approval."The Cystic Fibrosis Foundation, a non-profit organization dedicated to improving healthcare for people with cystic fibrosis, provided $150 million of the funding for the development for ivacaftor in exchange for royalty rights in the event that the medication was successfully developed and commercialized.  In 2014, the Foundation sold these royalty rights for $3.3 billion. The Foundation has stated that it intends to spend these funds in support of further research.Vertex said it would make the medication available free to patients in the United States with no insurance and a household income of under $150,000. In 2012, 24 US doctors and researchers involved in the development of the medication wrote to Vertex to protest the price of the medication, which had been set at about $300,000 per year. In the UK, the company provided the medication free for a limited time for certain patients, then left the hospitals to decide whether to continue to pay for it for those patients. UK agencies estimated the cost per quality adjusted life year (QALY) at between £335,000 and £1,274,000 —well above the National Institute for Health and Care Excellence thresholds.The medication was not covered under the Ontario Drug Benefit plan until June 2014, when the Government of Ontario and the manufacturer negotiated for what "Ontario Health Minister Deb Matthews had called a "fair price" for taxpayers". The negotiations took 16 months and it was estimated that around 20 Ontarians required the medication at the time.The province of Alberta began covering the medication in July 2014, and in September the province of Saskatchewan became the third province to include it in its provincial medication plan.Delay in agreement on a price for Vertex to charge national health plans led to patient group protests in Wales, England, and Australia.As of March 2016, the combination medication cost $259,000 a year in the United States.

Research
The clinical trials used in the regulatory approval of ivacaftor are described here.

G551D mutation
Of the approximately 70,000 cases of cystic fibrosis worldwide, 4% (~3,000) are due to a mutation called G551D.  The safety and efficacy of ivacaftor for the treatment of cystic fibrosis in patients with this mutation was examined in two clinical trials.The first trial was performed in adults having baseline respiratory function (FEV1) between 32% and 98% of normal for persons of similar age, height, and weight. The baseline average was 64%. Improvement in FEV1 was rapid and sustained.  At the end of 48 weeks, people treated with ivacaftor had on average an absolute increase in FEV1 of 10.4%, vs. a decline of 0.2% in the placebo group.  Pulmonary exacerbations were reduced by about half in the ivacaftor group relative to the placebo group.In a second trial conducted in children age six to 11, the average improvement in FEV1 was an absolute increase of 12.5% in the ivacaftor group at 48 weeks, compared to a very slight decline in the placebo group.

Other mutations
A third clinical trial examined the efficacy of ivacaftor in people with cystic fibrosis due to G1244E, G1349D, G178R, G551S, S1251N, S1255P, S549N, or S549R mutations.  This trial, which included 39 people of age greater than six years, used a crossover design.  The people in the trial had FEV1 averaging 78% of normal at baseline.  The people in the trial were randomized to receive either ivacaftor or placebo for eight weeks.  This was followed by a four to eight week washout period, then each group received the opposite treatment from what it received in the first part of the trial.  At week 8, the people on treatment with ivacaftor experienced an average absolute improvement in FEV1 of 13.8%, but there was a strong dependence of the efficacy on the exact mutation that a patient had. The detailed data for different mutation types is shown in the U.S package insert.

References
External links
"Ivacaftor". Drug Information Portal. U.S </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Fenfluramine and can you explain it in depth? [/INST] Fenfluramine, sold under the brand name Fintepla, is a serotonergic medication used for the treatment of seizures associated with Dravet syndrome and Lennox–Gastaut syndrome. It was formerly used as an appetite suppressant in the treatment of obesity, but was discontinued for this use due to cardiovascular toxicity before being repurposed for new indications. Fenfluramine was used for weight loss both alone under the brand name Pondimin and in combination with phentermine under the brand name Fen-Phen among others.Side effects of fenfluramine in people treated for seizures include decreased appetite, somnolence, sedation, lethargy, diarrhea, constipation, abnormal echocardiogram, fatigue, malaise, asthenia, ataxia, balance disorder, gait disturbance, increased blood pressure, drooling, excessive salivation, fever, upper respiratory tract infection, vomiting, appetite loss, weight loss, falls, and status epilepticus. Fenfluramine acts as a serotonin releasing agent, agonist of the serotonin 5-HT2 receptors, and σ1 receptor positive modulator. Its mechanism of action in the treatment of seizures is unknown, but may involve increased activation of certain serotonin receptors and the σ1 receptor.Fenfluramine was developed in the early 1960s and was first introduced for medical use as an appetite suppressant in France in 1963 followed by approval in the United States in 1973. In the 1990s, fenfluramine came to be associated with cardiovascular toxicity, and because of this, was withdrawn from the United States market in 1997. Subsequently, it was repurposed for the treatment of seizures and was reintroduced in the United States and the European Union in 2020. Fenfluramine is a schedule IV controlled substance in the United States.

Medical uses
Seizures
Fenfluramine is indicated for the treatment of seizures associated with Dravet syndrome and Lennox–Gastaut syndrome in people age two and older.Dravet syndrome is a life-threatening, rare and chronic form of epilepsy. It is often characterized by severe and unrelenting seizures despite medical treatment.

Obesity
Fenfluramine was formerly used as an appetite suppressant in the treatment of obesity, but was withdrawn for this use due to cardiovascular toxicity.

Adverse effects
The most common adverse reactions in people with seizures include decreased appetite; drowsiness, sedation and lethargy; diarrhea; constipation; abnormal echocardiogram; fatigue or lack of energy; ataxia (lack of coordination), balance disorder, gait disturbance (trouble with walking); increased blood pressure; drooling, salivary hypersecretion (saliva overproduction); pyrexia (fever); upper respiratory tract infection; vomiting; decreased weight; risk of falls; and status epilepticus.The U.S. Food and Drug Administration (FDA) fenfluramine labeling includes a boxed warning stating the drug is associated with valvular heart disease (VHD) and pulmonary arterial hypertension (PAH). Because of the risks of VHD and PAH, fenfluramine is available only through a restricted drug distribution program, under a risk evaluation and mitigation strategy (REMS). The fenfluramine REMS requires health care professionals who prescribe fenfluramine and pharmacies that dispense fenfluramine to be specially certified in the fenfluramine REMS and that patients be enrolled in the REMS. As part of the REMS requirements, prescribers and patients must adhere to the required cardiac monitoring with echocardiograms to receive fenfluramine.At higher therapeutic doses, headache, diarrhea, dizziness, dry mouth, erectile dysfunction, anxiety, insomnia, irritability, lethargy, and CNS stimulation have been reported with fenfluramine.There have been reports associating chronic fenfluramine treatment with emotional instability, cognitive deficits, depression, psychosis, exacerbation of pre-existing psychosis (schizophrenia), and sleep disturbances. It has been suggested that some of these effects may be mediated by serotonergic neurotoxicity/depletion of serotonin with chronic administration and/or activation of serotonin 5-HT2A receptors.

Heart valve disease
The distinctive valvular abnormality seen with fenfluramine is a thickening of the leaflet and chordae tendineae. One mechanism used to explain this phenomenon involves heart valve serotonin receptors, which are thought to help regulate growth. Since fenfluramine and its active metabolite norfenfluramine stimulate serotonin receptors, this may have led to the valvular abnormalities found in patients using fenfluramine. In particular norfenfluramine is a potent inhibitor of the re-uptake of 5-HT into nerve terminals. Fenfluramine and its active metabolite norfenfluramine affect the 5-HT2B receptors, which are plentiful in human cardiac valves. The suggested mechanism by which fenfluramine causes damage is through over or inappropriate stimulation of these receptors leading to inappropriate valve cell division. Supporting this idea is the fact that this valve abnormality has also occurred in patients using other drugs that act on 5-HT2B receptors.According to a study of 5,743 former users conducted by a plaintiffs expert cardiologist, damage to the heart valve continued long after stopping the medication. Of the users tested, 20% of women, and 12% of men were affected. For all ex-users, there was a 7-fold increase of chances of needing surgery for faulty heart valves caused by the drug.

Overdose
In overdose, fenfluramine can cause serotonin syndrome and rapidly result in death.

Pharmacology
Pharmacodynamics
Fenfluramine acts primarily as a serotonin releasing agent. It increases the level of serotonin, a neurotransmitter that regulates mood, appetite and other functions. Fenfluramine causes the release of serotonin by disrupting vesicular storage of the neurotransmitter, and reversing serotonin transporter function. The drug also acts as a norepinephrine releasing agent to a lesser extent, particularly via its active metabolite norfenfluramine. At high concentrations, norfenfluramine, though not fenfluramine, also acts as a dopamine releasing agent, and so fenfluramine may do this at very high doses as well. In addition to monoamine release, while fenfluramine binds only very weakly to the serotonin 5-HT2 receptors, norfenfluramine binds to and activates the serotonin 5-HT2B and 5-HT2C receptors with high affinity and the serotonin 5-HT2A receptor with moderate affinity. The result of the increased serotonergic and noradrenergic neurotransmission is a feeling of fullness and reduced appetite.
The combination of fenfluramine with phentermine, a norepinephrine–dopamine releasing agent acting primarily on norepinephrine, results in a well-balanced serotonin–norepinephrine releasing agent with weaker effects of dopamine release.
Fenfluramine was identified as a potent positive modulator of the σ1 receptor in 2020 and this action may be involved in its therapeutic benefits in the treatment of seizures.

Pharmacokinetics
The elimination half-life of fenfluramine has been reported as ranging from 13 to 30 hours. The mean elimination half-lives of its enantiomers have been found to be 19 hours for dexfenfluramine and 25 hours for levfenfluramine. Norfenfluramine, the major active metabolite of fenfluramine, has an elimination half-life that is about 1.5 to 2 times as long as that of fenfluramine, with mean values of 34 hours for dexnorfenfluramine and 50 hours for levnorfenfluramine.

Chemistry
Fenfluramine is a substituted amphetamine and is also known as 3-trifluoromethyl-N-ethylamphetamine. It is a racemic mixture of two enantiomers, dexfenfluramine and levofenfluramine. Some analogues of fenfluramine include norfenfluramine, benfluorex, flucetorex, and fludorex.

History
Fenfluramine was developed in the early 1960s and was introduced in France in 1963. Approximately 50 million Europeans were treated with fenfluramine for appetite suppression between 1963 and 1996. Fenfluramine was approved in the United States in 1973. The combination of fenfluramine and phentermine was proposed in 1984. Approximately 5 million people in the United States were given fenfluramine or dexfenfluramine with or without phentermine between 1996 and 1998.In the early 1990s, French researchers reported an association of fenfluramine with primary pulmonary hypertension and dyspnea in a small sample of patients. Fenfluramine was withdrawn from the U.S. market in 1997 after reports of heart valve disease and continued findings of pulmonary hypertension, including a condition known as cardiac fibrosis. It was subsequently withdrawn from other markets around the world. It was banned in India in 1998.Fenfluramine was an appetite suppressant which was used to treat obesity. It was used both on its own and, in combination with phentermine, as part of the anti-obesity medication Fen-Phen.In June 2020, fenfluramine was approved for medical use in the United States with an indication to treat Dravet syndrome.The effectiveness of fenfluramine for the treatment of seizures associated with Dravet syndrome was demonstrated in two clinical studies in 202 subjects between ages two and eighteen. The studies measured the change from baseline in the frequency of convulsive seizures. In both studies, subjects treated with fenfluramine had significantly greater reductions in the frequency of convulsive seizures during the trials than subjects who received placebo (inactive treatment). These reductions were seen within 3–4 weeks, and remained generally consistent over the 14- to 15-week treatment periods.The U.S. Food and Drug Administration (FDA) granted the application for fenfluramine priority review and orphan drug designations. The FDA granted approval of Fintepla to Zogenix, Inc.On 15 October 2020, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) adopted a positive opinion, recommending the granting of a marketing authorization for the medicinal product Fintepla, intended for the treatment of seizures associated with Dravet syndrome. Fenfluramine was approved for medical use in the European Union in December 2020.

Society and culture
Recreational use
Unlike various other amphetamine derivatives, fenfluramine is reported to be dysphoric, "unpleasantly lethargic", and non-addictive at therapeutic doses. However, it has been reported to be used recreationally at high doses ranging between 80 and 400 mg, which have been described as producing euphoria, amphetamine-like effects, sedation, and hallucinogenic effects, along with anxiety, nausea, diarrhea, and sometimes panic attacks, as well as depressive symptoms once the drug had worn off. At very high doses (e.g., 240 mg, or between 200 and 600 mg), fenfluramine induces a psychedelic state resembling that produced by lysergic acid diethylamide (LSD). Indirect (via induction of serotonin release) and/or direct activation of the 5-HT2A receptor would be expected to be responsible for the psychedelic effects of the drug at sufficient doses.

References
Further reading
Gustafsson BI, Tømmerås K, Nordrum I, Loennechen JP, Brunsvik A, Solligård E, Fossmark R, Bakke I, Syversen U, Waldum H (March 2005). "Long-term serotonin administration induces heart valve disease in rats". Circulation. 111 (12): 1517–22. doi:10.1161/01.CIR.0000159356.42064.48. PMID 15781732.
Welch, J. T.; Lim, D. S. (2007). "The Synthesis and Biological Activity of Pentafluorosulfanyl Analogs of Fluoxetine, Fenfluramine, and Norfenfluramine" </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Calcitonin and can you explain it in depth? [/INST] Calcitonin is a 32 amino acid peptide hormone secreted by parafollicular cells (also known as C cells) of the thyroid (or endostyle) in humans and other chordates. in the ultimopharyngeal body. It acts to reduce blood calcium (Ca2+), opposing the effects of parathyroid hormone (PTH).Its importance in humans has not been as well established as its importance in other animals, as its function is usually not significant in the regulation of normal calcium homeostasis. It belongs to the calcitonin-like protein family.
Historically calcitonin has also been called thyrocalcitonin.

Biosynthesis and regulation
Calcitonin is formed by the proteolytic cleavage of a larger prepropeptide, which is the product of the CALC1 gene (CALCA). It is functionally an antagonist with PTH and Vitamin D3. The CALC1 gene belongs to a superfamily of related protein hormone precursors including islet amyloid precursor protein, calcitonin gene-related peptide, and the precursor of adrenomedullin.
Secretion of calcitonin is stimulated by:

an increase in serum [Ca2+]
gastrin and pentagastrin.

Function
The hormone participates in calcium (Ca2+) metabolism. In many ways, calcitonin counteracts parathyroid hormone (PTH) and vitamin D.
More specifically, calcitonin lowers blood Ca2+ levels in two ways:

Major effect: Inhibits osteoclast activity in bones, which break down the bone
Minor effect: Inhibits renal tubular cell reabsorption of Ca2+ and phosphate, allowing them to be excreted in the urineHigh concentrations of calcitonin may be able to increase urinary excretion of calcium and phosphate via the renal tubules. leading to marked hypocalcemia. However, this is a minor effect with no physiological significance in humans. It is also a short-lived effect because the kidneys become resistant to calcitonin, as demonstrated by the kidneys unaffected excretion of calcium in patients with thyroid tumors that secrete excessive calcitonin.In its skeleton-preserving actions, calcitonin protects against calcium loss from the skeleton during periods of calcium mobilization, such as pregnancy and, especially, lactation. The protective mechanisms include the direct inhibition of bone resorption and the indirect effect through the inhibition of the release of prolactin from the pituitary gland. The reason provided is that prolactin induces the release of PTH related peptide which enhances bone resorption, but is still under investigation.Other effects are in preventing postprandial hypercalcemia resulting from absorption of Ca2+. Also, calcitonin inhibits food intake in rats and monkeys, and may have CNS action involving the regulation of feeding and appetite.
Calcitonin lowers blood calcium and phosphorus mainly through its inhibition of osteoclasts. Osteoblasts do not have calcitonin receptors and are therefore not directly affected by calcitonin levels. However, since bone resorption and bone formation are coupled processes, eventually calcitonins inhibition of osteoclastic activity leads to increased osteoblastic activity (as an indirect effect).

Receptor
The calcitonin receptor is a G protein-coupled receptor localized to osteoclasts as well kidney and brain cells. It is coupled to a Gsα subunit, thus stimulating cAMP production by adenylate cyclase in target cells. It may also affect the ovaries in women and the testes in men.

Discovery
Calcitonin was first purified in 1962 by Douglas Harold Copp and B. Cheney at the University of British Columbia, Canada. It was initially thought to be secreted by the parathyroid gland but was shown by Iain Macintyre and his team at the Royal Postgraduate Medical School, London, to be secreted by parafollicular cells of the thyroid gland. Dr. Copp named the discovered hormone calcitonin because of its role in maintaining normal calcium tone.

Medical significance
Calcitonin assay is used in identifying patients with nodular thyroid diseases. It is helpful in making an early diagnosis of medullary carcinoma of thyroid. A malignancy of the parafollicular cells, i.e. Medullary thyroid cancer, typically produces an elevated serum calcitonin level. Prognosis of MTC depends on early detection and treatment.
Calcitonin also has significantly impacted molecular biology, as the gene encoding calcitonin was the first gene discovered in mammalian cells to be alternatively spliced, now known to be a ubiquitous mechanism in eukaryotes.

Pharmacology
Calcitonin has clinically been used for metabolic bone disorders for more than 50 years. Salmon calcitonin is used for the treatment of:

Postmenopausal osteoporosis
Hypercalcaemia
Bone metastases
Pagets disease
Phantom limb painIt has been investigated as a possible non-operative treatment for spinal stenosis.The following information is from the UK Electronic Medicines Compendium

General characteristics of the active substance
Salmon calcitonin is rapidly absorbed and eliminated. Peak plasma concentrations are attained within the first hour of administration.
Animal studies have shown that calcitonin is primarily metabolised via proteolysis in the kidney following parenteral administration. The metabolites lack the specific biological activity of calcitonin. Bioavailability following subcutaneous and intramuscular injection in humans is high and similar for the two routes of administration (71% and 66%, respectively).
Calcitonin has short absorption and elimination half-lives of 10–15 minutes and 50–80 minutes, respectively. Salmon calcitonin is primarily and almost exclusively degraded in the kidneys, forming pharmacologically inactive fragments of the molecule. Therefore, the metabolic clearance is much lower in patients with end-stage kidney failure than in healthy subjects. However, the clinical relevance of this finding is not known.  Plasma protein binding is 30% to 40%.

Characteristics in patients
There is a relationship between the subcutaneous dose of calcitonin and peak plasma concentrations. Following parenteral administration of 100 IU calcitonin, peak plasma concentration lies between about 200 and 400 pg/ml. Higher blood levels may be associated with increased incidence of nausea, vomiting, and secretory diarrhea.

Preclinical safety data
Conventional long-term toxicity, reproduction, mutagenicity, and carcinogenicity studies have been performed in laboratory animals. Salmon calcitonin is devoid of embryotoxic, teratogenic, and mutagenic potential.
An increased incidence of pituitary adenomas has been reported in rats given synthetic salmon calcitonin for 1 year. This is considered a species-specific effect and of no clinical relevance. Salmon calcitonin does not cross the placental barrier.
In lactating animals given calcitonin, suppression of milk production has been observed. Calcitonin is secreted into the milk.

Pharmaceutical manufacture
Calcitonin was extracted from the ultimobranchial glands (thyroid-like glands) of fish, particularly salmon.  Salmon calcitonin resembles human calcitonin, but is more active.  At present, it is produced either by recombinant DNA technology or by chemical peptide synthesis.  The pharmacological properties of the synthetic and recombinant peptides have been demonstrated to be qualitatively and quantitatively equivalent.

Uses of calcitonin
Treatments
Calcitonin can be used therapeutically for the treatment of hypercalcemia or osteoporosis.
In a recent clinical study, subcutaneous injections of calcitonin have reduced the incidence of fractures and reduced the decrease in bone mass in women with type 2 diabetes complicated with osteoporosis.Subcutaneous injections of calcitonin in patients with mania resulted in significant decreases in irritability, euphoria and hyperactivity and hence calcitonin holds promise for treating bipolar disorder.  However no further work on this potential application of calcitonin has been reported.

Diagnostics
It may be used diagnostically as a tumor marker for medullary thyroid cancer, in which high calcitonin levels may be present and elevated levels after surgery may indicate recurrence </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Lisocabtagene maraleucel and can you explain it in depth? [/INST] Lisocabtagene maraleucel, sold under the brand name Breyanzi, is a cell-based gene therapy used to treat large B-cell lymphoma.Side effects include hypersensitivity reactions, serious infections, low blood cell counts, and a weakened immune system. The most common side effects include decreases in neutrophils (a type of white blood cell that fights infections), in red blood cells or in blood platelets (components that help the blood to clot), as well as cytokine release syndrome (a potentially life-threatening condition that can cause fever, vomiting, shortness of breath, pain and low blood pressure) and tiredness.Lisocabtagene maraleucel, a chimeric antigen receptor (CAR) T cell (CAR-T) therapy, is the third gene therapy approved by the U.S. Food and Drug Administration (FDA) for certain types of non-Hodgkin lymphoma, including diffuse large B-cell lymphoma (DLBCL). Lisocabtagene maraleucel was approved for medical use in the United States in February 2021.

Medical uses
Lisocabtagene maraleucel is indicated for the treatment of adults with relapsed or refractory large B-cell lymphoma (DLBCL) after two or more lines of systemic therapy, including diffuse large B-cell lymphoma (DLBCL) not otherwise specified (including DLBCL arising from indolent lymphoma), high-grade B-cell lymphoma, primary mediastinal large B-cell lymphoma (PMBCL), and follicular lymphoma grade 3B (FL3B).Lisocabtagene maraleucel is indicated for the treatment of adults with large B-cell lymphoma (LBCL) who have refractory disease to first-line chemoimmunotherapy or relapse within twelve months of first-line chemoimmunotherapy; or refractory disease to first-line chemoimmunotherapy or relapse after first-line chemoimmunotherapy and are not eligible for hematopoietic stem cell transplantation (HSCT) due to comorbidities or age.Lisocabtagene maraleucel is not indicated for the treatment of people with primary central nervous system lymphoma.

Adverse effects
The labeling carries a boxed warning for cytokine release syndrome (CRS), which is a systemic response to the activation and proliferation of CAR-T cells, causing high fever and flu-like symptoms and neurologic toxicities.

History
Lisocabtagene maraleucels safety and efficacy were established in a multicenter clinical trial of more than 250 adults with refractory or relapsed large B-cell lymphoma. The complete remission rate after treatment was 54%.The U.S. Food and Drug Administration (FDA) granted lisocabtagene maraleucel priority review, orphan drug, regenerative medicine advanced therapy (RMAT), and breakthrough therapy designations. Lisocabtagene maraleucel is the first regenerative medicine therapy with RMAT designation to be licensed by the FDA. The FDA granted approval of Breyanzi to Juno Therapeutics Inc., a Bristol-Myers Squibb Company.Efficacy was evaluated in TRANSFORM (NCT03575351), a randomized, open-label, multicenter trial in adults with primary refractory LBCL or relapse within twelve months of achieving complete response (CR) to first-line therapy. Participants had not yet received treatment for relapsed or refractory lymphoma and were potential candidates for autologous HSCT </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Ampicillin and can you explain it in depth? [/INST] Ampicillin is an antibiotic used to prevent and treat a number of bacterial infections, such as respiratory tract infections, urinary tract infections, meningitis, salmonellosis, and endocarditis. It may also be used to prevent group B streptococcal infection in newborns. It is used by mouth, by injection into a muscle, or intravenously.
Common side effects include rash, nausea, and diarrhea. It should not be used in people who are allergic to penicillin. Serious side effects may include Clostridium difficile colitis or anaphylaxis. While usable in those with kidney problems, the dose may need to be decreased. Its use during pregnancy and breastfeeding appears to be generally safe.Ampicillin was discovered in 1958 and came into commercial use in 1961. It is on the World Health Organizations List of Essential Medicines. The World Health Organization classifies ampicillin as critically important for human medicine. It is available as a generic medication.

Medical uses
Diseases
Bacterial meningitis; an aminoglycoside can be added to increase efficacy against gram-negative meningitis bacteria
Endocarditis by enterococcal strains (off-label use); often given with an aminoglycoside
Gastrointestinal infections caused by contaminated water or food (for example, by Salmonella)
Genito-urinary tract infections
Healthcare-associated infections that are related to infections from using urinary catheters and that are unresponsive to other medications
Otitis media (middle ear infection)
Prophylaxis (i.e. to prevent infection) in those who previously had rheumatic heart disease or are undergoing dental procedures, vaginal hysterectomies, or C-sections. It is also used in pregnant woman who are carriers of group B streptococci to prevent early-onset neonatal infections.
Respiratory infections, including bronchitis, pharyngitis
Sinusitis
Sepsis
Whooping cough, to prevent and treat secondary infectionsAmpicillin used to also be used to treat gonorrhea, but there are now too many strains resistant to penicillins.

Bacteria
Ampicillin is used to treat infections by many gram-positive and gram-negative bacteria. It was the first "broad spectrum" penicillin with activity against gram-positive bacteria, including Streptococcus pneumoniae, Streptococcus pyogenes, some isolates of Staphylococcus aureus (but not penicillin-resistant or methicillin-resistant strains), Trueperella, and some Enterococcus. It is one of the few antibiotics that works against multidrug resistant Enterococcus faecalis and E. faecium. Activity against gram-negative bacteria includes Neisseria meningitidis, some Haemophilus influenzae, and some of the Enterobacteriaceae (though most Enterobacteriaceae and Pseudomonas are resistant). Its spectrum of activity is enhanced by co-administration of sulbactam, a drug that inhibits beta lactamase, an enzyme produced by bacteria to inactivate ampicillin and related antibiotics. It is sometimes used in combination with other antibiotics that have different mechanisms of action, like vancomycin, linezolid, daptomycin, and tigecycline.

Available forms
Ampicillin can be administered by mouth, an intramuscular injection (shot) or by intravenous infusion. The oral form, available as capsules or oral suspensions, is not given as an initial treatment for severe infections, but rather as a follow-up to an IM or IV injection. For IV and IM injections, ampicillin is kept as a powder that must be reconstituted.IV injections must be given slowly, as rapid IV injections can lead to convulsive seizures.

Specific populations
Ampicillin is one of the most used drugs in pregnancy, and has been found to be generally harmless both by the Food and Drug Administration in the U.S. (which classified it as category B) and the Therapeutic Goods Administration in Australia (which classified it as category A). It is the drug of choice for treating Listeria monocytogenes in pregnant women, either alone or combined with an aminoglycoside. Pregnancy increases the clearance of ampicillin by up to 50%, and a higher dose is thus needed to reach therapeutic levels.Ampicillin crosses the placenta and remains in the amniotic fluid at 50–100% of the concentration in maternal plasma; this can lead to high concentrations of ampicillin in the newborn.While lactating mothers secrete some ampicillin into their breast milk, the amount is minimal.In newborns, ampicillin has a longer half-life and lower plasma protein binding. The clearance by the kidneys is lower, as kidney function has not fully developed.

Contraindications
Ampicillin is contraindicated in those with a hypersensitivity to penicillins, as they can cause fatal anaphylactic reactions. Hypersensitivity reactions can include frequent skin rashes and hives, exfoliative dermatitis, erythema multiforme, and a temporary decrease in both red and white blood cells.Ampicillin is not recommended in people with concurrent mononucleosis, as over 40% of patients develop a skin rash.

Side effects
Ampicillin is comparatively less toxic than other antibiotics, and side effects are more likely in those who are sensitive to penicillins and those with a history of asthma or allergies. In very rare cases, it causes severe side effects such as angioedema, anaphylaxis, and C. difficile infection (that can range from mild diarrhea to serious pseudomembranous colitis). Some develop black "furry" tongue. Serious adverse effects also include seizures and serum sickness. The most common side effects, experienced by about 10% of users are diarrhea and rash. Less common side effects can be nausea, vomiting, itching, and blood dyscrasias. The gastrointestinal effects, such as hairy tongue, nausea, vomiting, diarrhea, and colitis, are more common with the oral form of penicillin. Other conditions may develop up several weeks after treatment.

Overdose
Ampicillin overdose can cause behavioral changes, confusion, blackouts, and convulsions, as well as neuromuscular hypersensitivity, electrolyte imbalance, and kidney failure.

Interactions
Ampicillin reacts with probenecid and methotrexate to decrease renal excretion. Large doses of ampicillin can increase the risk of bleeding with concurrent use of warfarin and other oral anticoagulants, possibly by inhibiting platelet aggregation. Ampicillin has been said to make oral contraceptives less effective, but this has been disputed. It can be made less effective by other antibiotic, such as chloramphenicol, erythromycin, cephalosporins, and tetracyclines. For example, tetracyclines inhibit protein synthesis in bacteria, reducing the target against which ampicillin acts. If given at the same time as aminoglycosides, it can bind to it and inactivate it. When administered separately, aminoglycosides and ampicillin can potentiate each other instead.Ampicillin causes skin rashes more often when given with allopurinol.Both the live cholera vaccine and live typhoid vaccine can be made ineffective if given with ampicillin. Ampicillin is normally used to treat cholera and typhoid fever, lowering the immunological response that the body has to mount.

Pharmacology
Mechanism of action
Ampicillin is in the penicillin group of beta-lactam antibiotics and is part of the aminopenicillin family. It is roughly equivalent to amoxicillin in terms of activity. Ampicillin is able to penetrate gram-positive and some gram-negative bacteria. It differs from penicillin G, or benzylpenicillin, only by the presence of an amino group. This amino group, present on both ampicillin and amoxicillin, helps these antibiotics pass through the pores of the outer membrane of gram-negative bacteria, such as E. coli, Proteus mirabilis, Salmonella enterica, and Shigella.Ampicillin acts as an irreversible inhibitor of the enzyme transpeptidase, which is needed by bacteria to make the cell wall. It inhibits the third and final stage of bacterial cell wall synthesis in binary fission, which ultimately leads to cell lysis; therefore, ampicillin is usually bacteriolytic.

Pharmacokinetics
Ampicillin is well-absorbed from the GI tract (though food reduces its absorption), and reaches peak concentrations in one to two hours. The bioavailability is around 62% for parenteral routes. Unlike other penicillins, which usually bind 60–90% to plasma proteins, ampicillin binds to only 15–20%.Ampicillin is distributed through most tissues, though it is concentrated in the liver and kidneys. It can also be found in the cerebrospinal fluid when the meninges become inflamed (such as, for example, meningitis). Some ampicillin is metabolized by hydrolyzing the beta-lactam ring to penicilloic acid, though most of it is excreted unchanged. In the kidneys, it is filtered out mostly by tubular secretion; some also undergoes glomerular filtration, and the rest is excreted in the feces and bile.
Hetacillin and pivampicillin are ampicillin esters that have been developed to increase bioavailability.

History
Ampicillin has been used extensively to treat bacterial infections since 1961. Until the introduction of ampicillin by the British company Beecham, penicillin therapies had only been effective against gram-positive organisms such as staphylococci and streptococci. Ampicillin (originally branded as "Penbritin") also demonstrated activity against gram-negative organisms such as H </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Midodrine and can you explain it in depth? [/INST] Midodrine is a vasopressor/antihypotensive agent (it raises the blood pressure).  Midodrine was approved in the United States by the Food and Drug Administration (FDA) in 1996 for the treatment of dysautonomia and orthostatic hypotension.  In August 2010, the FDA proposed withdrawing this approval because the manufacturer, Shire plc, failed to complete required studies after the medicine reached the market. In September 2010, the FDA reversed its decision to remove midodrine from the market and allowed it to remain available to patients while Shire plc collected further data regarding the efficacy and safety of the drug. Shire announced on September 22, 2011, that it was withdrawing completely from supplying midodrine and leaving it to several generics to supply the drug.

Medical uses
Midodrine is indicated for the treatment of symptomatic orthostatic hypotension. It can reduce dizziness and faints by about a third, but can be limited by troublesome goose bumps, skin itch, gastrointestinal discomfort, chills, elevated blood pressure while lying down, and urinary retention. A meta-analysis of clinical trials of midodrine or droxidopa in patients with low blood pressure when standing found that midodrine increased standing blood pressure more than droxidopa but that midodrine but not droxidopa increased the risk of high blood pressure when lying down. Small studies have also shown that midodrine can be used to prevent excessive drops in blood pressure in people requiring dialysis.Midodrine has been used in the complications of cirrhosis. It is also used with octreotide for hepatorenal syndrome; the proposed mechanism is constriction of splanchnic vessels and dilation of renal vasculature. Studies have not been sufficiently well conducted to show a clear place for midodrine.

Contraindications
Midodrine is contraindicated in patients with severe organic heart disease, acute kidney disease, urinary retention, pheochromocytoma or thyrotoxicosis. Midodrine should not be used in patients with persistent and excessive supine hypertension.

Side effects
Headache, feeling of pressure/fullness in the head, vasodilation/flushing face, scalp tingling, confusion/thinking abnormality, dry mouth, nervousness/anxiety and rash.

Pharmacology
Mechanism of action
Midodrine is a prodrug which forms an active metabolite, desglymidodrine, which is an α1-receptor agonist and exerts its actions via activation of the alpha-adrenergic receptors of the arteriolar and venous vasculature, producing an increase in vascular tone and elevation of blood pressure </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Triethylenetetramine and can you explain it in depth? [/INST] Triethylenetetramine (TETA and trien), also known as trientine (INN) when used medically, is an organic compound with the formula [CH2NHCH2CH2NH2]2. The pure freebase is a colorless oily liquid, but, like many amines, older samples assume a yellowish color due to impurities resulting from air-oxidation. It is soluble in polar solvents.  The branched isomer tris(2-aminoethyl)amine and piperazine derivatives may also be present in commercial samples of TETA.
The hydrochloride salts are used medically as a treatment for copper toxicity.

Uses
The reactivity and uses of TETA are similar to those for the related polyamines ethylenediamine and diethylenetriamine.  It is primarily used as a crosslinker ("hardener") in epoxy curing.

Medical uses
The hydrochloride salt of TETA, referred to as trientine hydrochloride, is a chelating agent that is used to bind and remove copper in the body to treat Wilsons disease, particularly in those who are intolerant to penicillamine. Some recommend trientine as first-line treatment, but experience with penicillamine is more extensive.Trientine hydrochloride (brand name Syprine) was approved for medical use in the United States in November 1985.Trientine tetrahydrochloride (brand name Cuprior) was approved for medical use in the European Union in September 2017. It is indicated for the treatment of Wilsons disease in adults, adolescents and children five years of age or older who are intolerant to D-penicillamine therapy.Trientine dihydrochloride (brand name Cufence) was approved for medical use in the European Union in July 2019. It is indicated for the treatment of Wilsons disease in adults, adolescents and children five years of age or older who are intolerant to D-penicillamine therapy.The most common side effects include nausea, especially when starting treatment, skin rash, duodenitis (inflammation of the duodenum, the part of the gut leading out of the stomach), and severe colitis (inflammation in the large bowel causing pain and diarrhea).

Society and culture
Controversies
In the United States, Valeant Pharmaceuticals International raised the price of its Syprine brand of TETA from $625 to $21,267 for 100 pills over five years. The New York Times said that this "egregious" price increase caused public outrage. Teva Pharmaceuticals developed a generic, which patients and doctors expected to be cheaper, but when it was introduced in February 2018, Tevas price was $18,375 for 100 pills. Aaron Kesselheim, who studies drug pricing at Harvard Medical School, said that drug companies price the product at what they think the market will bear.

Production
TETA is prepared by heating ethylenediamine or ethanolamine/ammonia mixtures over an oxide catalyst.  This process gives a variety of amines, especially ethylene amines which are separated by distillation and sublimation.

Coordination chemistry
TETA is a tetradentate ligand in coordination chemistry, where it is referred to as trien </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Belzutifan and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Potassium phosphate and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Ecallantide and can you explain it in depth? [/INST]  </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Oxymetazoline and can you explain it in depth? [/INST] Oxymetazoline, sold under the brand name Afrin among others, is a topical decongestant and vasoconstrictor medication. It is available over-the-counter as a nasal spray to treat nasal congestion and nosebleeds, as eyedrops to treat eye redness due to minor irritation, and (in the United States) as a prescription topical cream to treat persistent facial redness due to rosacea in adults. Its effects begin within minutes and last for up to 6 hours. Intranasal use for longer than three days may cause congestion to recur or worsen, resulting in physical dependence.
Oxymetazoline is a derivative of imidazole. It was developed from xylometazoline at E. Merck Darmstadt by Wolfgang Fruhstorfer and Helmut Müller-Calgan in 1961. A direct sympathomimetic, oxymetazoline binds to and activates α1 adrenergic receptors and α2 adrenergic receptors, most notably. One study classified it in the following order: α(2A) > α(1A) ≥ α(2B) > α(1D) ≥ α(2C) >> α(1B), but this is not universally agreed upon. There is little consistency across the (relatively large) number of in-vitro studies with respect to binding affinity/selectivity.

Medical uses
Oxymetazoline is available over-the-counter as a topical decongestant in the form of oxymetazoline hydrochloride in nasal sprays such as Otrivin, Afrin, Operil, Dristan, Dimetapp, Oxyspray, Facimin, Nasivin, Nostrilla, Utabon, Sudafed OM, Vicks Sinex, Zicam, SinuFrin, Drixoral
and Mucinex Full Force.In the United States, oxymetazoline 1% cream is approved by the Food and Drug Administration for topical treatment of persistent facial erythema (redness) associated with rosacea in adults.Due to its vasoconstricting properties, oxymetazoline is also used to treat nose bleeds and eye redness due to minor irritation (marketed as Visine L.R. in the form of eye drops). In July 2020, oxymetazoline received approval by the FDA for the treatment of acquired drooping eyelid.

Side effects
Rebound congestion
Rebound congestion, or rhinitis medicamentosa, may occur. A 2006 review of the pathology of rhinitis medicamentosa concluded that use of oxymetazoline for more than three days may result in rhinitis medicamentosa and recommended limiting use to three days.

Australian regulatory submission
In a submission to the Therapeutic Goods Administration, a Novartis representative concluded, "The justification was not based on evidence." Citing an existing extensive body of evidence and noting a range of recommended periods from five to ten days, Novartis recommended the established five day period for its use for self-medication without medical consultation as it coincides with the typical duration of the common cold.

Use in pregnancy
The Food and Drug Administration places oxymetazoline in category C, indicating risk to the fetus cannot be ruled out.  While it has been shown that a single dose does not significantly alter either maternal or fetal circulation, this subject has not been studied extensively enough to draw reliable conclusions.

Overdose
If accidentally ingested, standard methods to remove unabsorbed drugs should be considered. There is no specific antidote for oxymetazoline, although its pharmacological effects may be reversed by an adrenergic antagonists such as phentolamine. In the event of a possibly life-threatening overdose (such as a hypertensive crisis), benzodiazepines should be considered to decrease the likelihood of seizures and convulsions, as well as reduce anxiety and to lower blood pressure. In children, oxymetazoline may produce profound central nervous system depression due to stimulation of central α2 receptors and imidazoline receptors, much like clonidine.

Pharmacology
Pharmacodynamics
Oxymetazoline is a sympathomimetic that selectively agonizes α1 and, partially, α2 adrenergic receptors. Since vascular beds widely express α1 receptors, the action of oxymetazoline results in vasoconstriction. In addition, the local application of the drug also results in vasoconstriction due to its action on endothelial postsynaptic α2 receptors; systemic application of α2 agonists, in contrast, causes vasodilation because of centrally-mediated inhibition of sympathetic tone via presynaptic α2 receptors. Vasoconstriction of vessels results in relief of nasal congestion in two ways: first, it increases the diameter of the airway lumen; second, it reduces fluid exudation from postcapillary venules </s>


<s> [INST] <<SYS>> You are a responsible assistant committed to providing accurate and helpful responses. Avoid sharing harmful or biased content. Clarify any unclear or incorrect questions rather than providing false or misleading information. <</SYS>> What is Cetirizine and can you explain it in depth? [/INST] Cetirizine, sold under the brand name Zyrtec among others, is a second-generation antihistamine used to treat allergic rhinitis (hay fever), dermatitis, and urticaria (hives). It is taken by mouth. Effects generally begin within thirty minutes and last for about a day. The degree of benefit is similar to other antihistamines such as diphenhydramine.Common side effects include sleepiness, dry mouth, headache, and abdominal pain. The degree of sleepiness that occurs is generally less than with first generation antihistamines. Use in pregnancy appears safe, but use during breastfeeding is not recommended. The medication works by blocking histamine H1 receptors, mostly outside the brain.It was patented in 1981 and came into medical use in 1987. It is on the World Health Organizations List of Essential Medicines. It is available as a generic medication. In 2020, it was the 52nd most commonly prescribed medication in the United States, with more than 13 million prescriptions.

Medical uses
Allergies
Cetirizines primary indication is for hay fever and other allergies. Because the symptoms of itching and redness in these conditions are caused by histamine acting on the H1 receptor, blocking those receptors temporarily relieves those symptoms.Cetirizine is also commonly prescribed to treat acute and (in particular cases) chronic urticaria, more efficiently than any other second-generation antihistamine.

Available forms
Cetirizine is available over-the-counter in the US in the form of 5 and 10 mg tablets. A 20 mg strength is available by prescription only. It is also available as a 1 mg/mL syrup for oral administration by prescription.
In the UK, up to 30 tablets of 10 mg are on the general sales list (of pharmaceuticals) and can be purchased without a prescription and without pharmacist supervision. The drug can be in the form of tablets, capsules or a syrup.

Adverse effects
Commonly reported side effects of cetirizine include headache, dry mouth, drowsiness, and fatigue, while more serious but rare adverse effects reported include tachycardia and edema.Discontinuing cetirizine after prolonged use (typically, use beyond six months) may result in generalized itching.

Pharmacology
Pharmacodynamics
Cetirizine acts as a highly selective antagonist of the histamine H1 receptor. The Ki values for the H1 receptor are approximately 6 nM for cetirizine, 3 nM for levocetirizine, and 100 nM for dextrocetirizine, indicating that the levorotatory enantiomer is the main active form. Cetirizine has 600-fold or greater selectivity for the H1 receptor over a wide variety of other sites, including muscarinic acetylcholine, serotonin, dopamine, and α-adrenergic receptors, among many others. The drug shows 20,000-fold or greater selectivity for the H1 receptor over the five muscarinic acetylcholine receptors, and hence does not exhibit anticholinergic effects. It shows negligible inhibition of the hERG channel (IC50 > 30 μM) and no cardiotoxicity has been observed with cetirizine at doses of up to 60 mg/day, six times the normal recommended dose and the highest dose of cetirizine that has been studied in healthy subjects.Cetirizine crosses the blood-brain barrier only slightly, and for this reason, produces minimal sedation compared to many other antihistamines. A positron emission tomography (PET) study found that brain occupancy of the H1 receptor was 12.6% for 10 mg cetirizine, 25.2% for 20 mg cetirizine, and 67.6% for 30 mg hydroxyzine. (A 10 mg dose of cetirizine equals about a 30 mg dose of hydroxyzine in terms of peripheral antihistamine effect.) PET studies with antihistamines have found that brain H1 receptor occupancy of more than 50% is associated with a high prevalence of somnolence and cognitive decline, whereas brain H1 receptor occupancy of less than 20% is considered to be non-sedative. In accordance, H1 receptor occupancy correlated well with subjective sleepiness for 30 mg hydroxyzine but there was no correlation for 10 or 20 mg cetirizine. As such, brain penetration and brain H1 receptor occupancy by cetirizine are dose-dependent, and in accordance, while cetirizine at doses of 5 to 10 mg have been reported to be non-sedating or mildly sedating, a higher dose of 20 mg has been found to induce significant drowsiness in other studies.Cetirizine also shows anti-inflammatory properties independent of H1 receptors. The effect is exhibited through suppression of the NF-κB pathway, and by regulating the release of cytokines and chemokines, thereby regulating the recruitment of inflammatory cells. It has been shown to inhibit eosinophil chemotaxis and LTB4 release. At a dosage of 20 mg, Boone et al. found that it inhibited the expression of VCAM-1 in patients with atopic dermatitis.

Pharmacokinetics
Absorption
Cetirizine is rapidly and extensively absorbed upon oral administration in tablet or syrup form. The oral bioavailability of cetirizine is at least 70% and of levocetirizine is at least 85%. The Tmax of cetirizine is approximately 1.0 hour regardless of formulation. The pharmacokinetics of cetirizine have been found to increase linearly with dose across a range of 5 to 60 mg. Its Cmax following a single dose has been found to be 257 ng/mL for 10 mg and 580 ng/mL for 20 mg. Food has no effect on the bioavailability of cetirizine but has been found to delay the Tmax by 1.7 hours (i.e., to approximately 2.7 hours) and to decrease the Cmax by 23%. Similar findings were reported for levocetirizine, which had its Tmax delayed by 1.25 hours and its Cmax decreased by about 36% when administered with a high-fat meal. Steady-state levels of cetirizine occur within 3 days and there is no accumulation of the drug with chronic administration. Following once-daily administration of 10 mg cetirizine for ten days, the mean Cmax was 311 ng/mL.

Distribution
The mean plasma protein binding of cetirizine has been found to be 93 to 96% across a range of 25 to 1,000 ng/mL independent of concentration. Plasma protein binding of 88 to 96% has also been reported across multiple studies. The drug is bound to albumin with high affinity, while α1-acid glycoprotein and lipoproteins contribute much less to total plasma protein binding. The unbound or free fraction of levocetirizine has been reported to be 8%. The true volume of distribution of cetirizine is unknown but is estimated to be 0.3 to 0.45 L/kg. Cetirizine poorly and slowly crosses the blood-brain barrier, which is thought to be due to its chemical properties and its activity as a P-glycoprotein substrate.

Metabolism
Cetirizine does not undergo extensive metabolism. It is notably not metabolized by the cytochrome P450 system. Because of this, it does not interact significantly with drugs that inhibit or induce cytochrome P450 enzymes such as theophylline, erythromycin, clarithromycin, cimetidine, or alcohol. While cetirizine does not undergo extensive metabolism or metabolism by the cytochrome P450 enzyme, it does undergo some metabolism by other means, the metabolic pathways of which include oxidation and conjugation. Plasma radioactivity attributed to unchanged cetirizine is more than 90% at 2 hours, 80% at 10 hours, and 70% at 24 hours, indicating limited and slow metabolism. The enzymes responsible for transformation of cetirizine have not been identified.

Elimination
Cetirizine is eliminated approximately 70 to 85% in the urine and 10 to 13% in the feces. About 50 or 60% of cetirizine eliminated in the urine is unchanged. It is eliminated in the urine via an active transport mechanism. The elimination half-life of cetirizine ranges from 6.5 to 10 hours in healthy adults, with a mean across studies of approximately 8.3 hours. Its duration of action is at least 24 hours. The elimination half-life of cetirizine is increased in the elderly (to 12 hours), in hepatic impairment (to 14 hours), and in renal impairment (to 20 hours).

Chemistry
Cetirizine contains L- and D-stereoisomers </s>