What is Crixivan used for?
- HIV infection. Crixivan must be used in combination with other anti-HIV medicines.
How does Crixivan work?
Crixivan capsules contain the active ingredient indinavir, which is a type of medicine called a protease inhibitor. It is used in the treatment of HIV (human immunodeficiency virus) infection.
AIDS (acquired immune deficiency syndrome) is caused by infection with HIV. This virus invades cells of the immune system, particularly the white blood cells known as CD4 T-helper lymphocytes. These cells normally work to activate other cells in the immune system to fight infection. Since HIV kills CD4 T-helper cells, over time the body becomes less able to fight the virus or subsequent infections.
Once the virus has invaded a CD4 T-cell it multiplies, and new copies of the virus are released to infect more CD4 cells. Certain chemicals produced by HIV, called enzymes, play an important role in this multiplication. One of these enzymes, protease, has an essential involvement in assembling the new copies of the virus. Indinavir works by stopping the protease enzyme from working. This means that new copies of the virus that are produced are faulty and cannot infect more CD4 cells.
There is no cure for HIV, but indinavir is one of a number of medications that lower the amount of virus in the body (viral load), help the immune system to recover, and therefore slow down or stop the progression of the disease from HIV to AIDS.
A combination of several anti-HIV medicines is required to fight HIV because the virus can become resistant to one agent very quickly. This is known as combined antiretroviral therapy (cART) or highly active antiretroviral therapy (HAART). Indinavir is used with other anti-HIV drugs that attack the HIV virus in different ways. This minimises the virus's ability to replicate and multiply, and helps prevent it becoming resistant to treatment.
How do I take Crixivan?
- It is important to follow the instructions given by your doctor or pharmacist regarding how many Crixivan capsules to take and how often to take them. This will depend on what other anti-HIV medicines you are taking. If you are unclear about anything you should ask your doctor or pharmacist for advice.
- Crixivan capsules must be swallowed whole with a drink of water and not opened, crushed or chewed.
- Crixivan capsules are usually taken three times a day (every 8 hours). The capsules should be taken one hour before or two hours after a meal. If necessary the medicine can be taken with a low-fat, light meal.
- Crixivan is sometimes used together with another anti-HIV medicine called ritonavir (Norvir). A low-dose of ritonavir increases the amount of indinavir in the bood and is used to boost the effect of the indinavir, rather than to have any effect on the virus itself. Crixivan is taken twice a day (every 12 hours) in combination with ritonavir. If you are prescribed Crixivan with ritonavir you can take it either with or without food.
- If you are taking Crixivan in combination with didanosine (Videx) tablets you should leave one hour between taking each medicine, because the antacids in didanosine tablets reduce the absorption of indinavir from the gut.
- Try to take your medicine regularly at the same times each day. If you forget to take a dose just take your next dose as usual when it is due. Do not take a double dose to make up for a missed dose.
- You must keep taking this medicine regularly every day as prescribed, unless your doctor tells you to stop.
Important information about Crixivan
- The HIV virus is very good at becoming resistant to anti-HIV medicines. For this reason it is very important that you carefully follow your doctor's instructions for taking your anti-HIV medicines, in order to maintain effective levels of the medicines in your blood. If the blood levels of the medicines drop, the virus will be given more chance to replicate and develop resistance to the drugs. Skipping even a few doses increases the risk of treatment failure, so you should make sure that you take all your doses at the correct time, and that you visit your doctor for repeat prescriptions before you run out of medicine.
- Treatment of HIV infection with anti-HIV medicines such as this one has been shown to reduce the risk of transmitting the virus to other people through sexual contact. However, it does not remove this risk entirely. You should continue to use condoms to prevent transmitting the virus to your sexual partner.
- This medicine can commonly cause kidney stones, and for this reason it is important that you drink plenty of fluids (at least 1.5 litres in every 24 hours) while you are taking it. Children taking this medicine are at a higher risk of kidney stones than adults. If you get any symptoms of kidney stones, for example pain in your lower back or blood in your urine, you should consult your doctor. You may need to stop taking this medicine for a few days.
- People taking antiretroviral medicines may gain weight and may also experience increases in the levels of sugar and fats in their blood. However these changes are in part linked to the improvement in control over your HIV and your lifestyle. Your doctor may want to monitor the levels of lipids (eg cholesterol) and sugar (glucose) in your blood, and may prescribe additional medicines for any lipid disorders that occur during treatment with this medicine.
- Some people being treated with combination antiretroviral therapy may develop a bone condition called osteonecrosis. This condition is caused by loss of blood supply to a bone, causing death of the bone tissue. The risk of the condition is thought to be increased by corticosteroid use, alcohol consumption, severe immunosuppression, higher body mass index, advanced HIV disease and long-term use of antiretroviral medicines. If you notice any joint stiffness, aches and pains (especially of the hip, knee and shoulder) or difficulty in movement while using this medicine, you should tell your doctor so this can be investigated.
- If you have advanced HIV and a history of opportunistic infections such as pneumocystis carinii pneumonia (PCP) or cytomegalovirus (CMV), you may experience signs and symptoms of inflammation from previous infections soon after you start combination anti-HIV treatment. It is believed that these symptoms are due to an improvement in the body's immune response, which enables the body to fight infections that may have been present with no obvious symptoms. You should tell your doctor immediately if you experience any signs or symptoms of infection, such as inflammation or high temperature, after starting treatment with this medicine.
- If you have any problems with your liver, in particular chronic hepatitis B or C, you will need to have regular blood tests to monitor your liver while you are taking this medicine. Symptoms that may suggest a liver problem include persistent nausea and vomiting, abdominal pain, or the development of jaundice (a yellow colouring to the skin and the whites of the eyes). Consult your doctor if you experience any of these symptoms. People with liver problems also have a higher risk of developing kidney stones.
- You should store your Crixivan capsules in the container in which they were dispensed and not transfer them to another container. This is because the original container contains a dessicant that stops the capsules absorbing moisture.
Crixivan should be used with caution in
- Decreased liver function.
- Liver disease, particularly chronic hepatitis B or hepatitis C.
- People with the blood clotting disorder haemophilia (this medicine may increase the risk of bleeding in people with haemophilia).
- People with hereditary blood disorders called porphyrias.
- Diabetes (this medicine may increase blood sugar levels).
Crixivan should not be used in
- People with rare hereditary problems of galactose intolerance, the Lapp lactose deficiency or glucose-galactose malabsorption (Crixivan capsules contain lactose).
- Crixivan must not be used in combination with ritonavir in people with severe liver problems.
- Crixivan is not recommended for children under 18 years of age and has not been studied in children under four years of age.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy.
If you feel you have experienced an allergic reaction, stop using this medicine and inform your doctor or pharmacist immediately.
Pregnancy and breastfeeding
Certain medicines should not be used during pregnancy or breastfeeding. However, other medicines may be safely used in pregnancy or breastfeeding providing the benefits to the mother outweigh the risks to the unborn baby. Always inform your doctor if you are pregnant or planning a pregnancy, before using any medicine.
- The safety of indinavir for use during pregnancy has not been fully established. However, combined antiretroviral therapy is widely used to help prevent transmission of HIV infection from a pregnant woman to her developing baby. This should only be prescribed by specialists in HIV infection and it is important to get medical advice from your doctor straight away if you think you could be pregnant while you are taking this medicine.
- In the UK it is currently recommended that women infected with HIV should not breastfeed their infants, regardless of their treatment, in order to avoid transmitting the virus to the baby in the breast milk. Mothers are advised to feed their babies with formula from birth. You should discuss this with your doctor.
Possible side effects of Crixivan
Medicines and their possible side effects can affect individual people in different ways. The following are some of the side effects that are known to be associated with this medicine. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect.
Very common (affect more than 1 in 10 people)
- Feeling weak or tired.
- Indigestion or abdominal pain.
- Nausea and vomiting.
- Alteration in taste.
- Dry skin.
- Blood or protein in the urine.
Common (affect between 1 in 10 and 1 in 100 people)
- Kidney stones (see important information section above).
- Pain in the muscles (myalgia).
- Dry mouth.
- Wind (flatulence).
- Difficulty sleeping (insomnia).
- Pins and needles or numb sensations.
- Increase in the level of cholesterol and triglycerides in the blood.
- Increased blood sugar levels and diabetes.
- Kidney failure.
- Alteration in results of liver function tests.
- Liver problems such as hepatitis or jaundice.
- Inflammation of the pancreas (pancreatitis).
- Decreased numbers of red blood cells in the blood (anaemia).
- Decreased numbers of platelets in the blood (thrombocytopenia).
- Serious skin reactions such as Stevens-Johnson syndrome.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with this medicine, please read the information provided with the medicine or consult your doctor or pharmacist.
If you think you have experienced a side effect from a medicine or vaccine you should check the patient information leaflet. This lists the known side effects and what to do if you get them. You can also get advice from your doctor, nurse or pharmacist. If they think it's necessary they'll report it for you.
You can also report side effects yourself using the yellow card website: www.mhra.gov.uk/yellowcard.
How can Crixivan affect other medicines?
It is very important to tell your doctor or pharmacist what medicines you are already taking, including those bought without a prescription and herbal medicines, before you start treatment with this medicine. Similarly, you must check with your doctor or pharmacist before taking any new medicines while taking this one, to make sure that the combination is safe.
Your doctor may need to adjust the doses of other anti-HIV medicines you are already taking when this medicine is added to your treatment. Atazanavir and etravirine are not recommended for use in combination with indinavir.
If you are taking Videx tablets as part of your anti-HIV medication, you should not take them within an hour of taking Crixivan. This is because the antacids in Videx tablets reduce absorption of indinavir from the gut.
The following medicines must not be used in combination with indinavir, because indinavir may increase the levels of these medicines in the blood and subsequently increase the risk of serious side effects:
- ergot derivatives, eg ergotamine, ergometrine, dihydroergotamine, methysergide
- midazolam taken by mouth
The following medicines should not be used in combination with indinavir taken with ritonavir:
- fusidic acid
The following medicines should not be taken in combination with indinavir because they increase the breakdown of indinavir in the body and could make it less effective against HIV:
- the herbal remedy St John's wort (Hypericum perforatum).
Indinavir may increase the blood level of several other medicines, including the following, and so could increase the risk of their side effects. You may need extra monitoring or lowered doses if you are prescribed any of these with indinavir:
- atorvastatin (used for lowering cholesterol levels). As this may increase the risk of side effects on the muscles, it should be used with caution in people taking indinavir. If a statin medicine is needed to lower cholesterol levels, pravastatin or fluvastatin are preferred.
- calcium-channel blockers, eg nifedipine, nicardipine, felodipine
- corticosteroids such as fluticasone and budesonide taken by inhaler or nasal spray. This could increase the risk of systemic side effects of these steroids, such as Cushing's syndrome, or decreased production of natural steroids by the adrenal glands.
- midazolam given by injection
The following medicines may increase the blood level of indinavir. If you are prescribed one of these your doctor may need to lower your dose of indinavir:
The following medicines may decrease the blood level of indinavir. If you are taking any of these, your doctor may need to prescribe you a larger dose of indinavir:
- rifabutin (indinavir also increases the blood level of rifabutin - the combination is not recommended)
The weight loss medicine orlistat has been reported to reduce the absorption of anti-HIV medicines from the gut and could make them less effective.
Other medicines containing the same active ingredient
There are currently no other medicines available in the UK that contain indinavir as the active ingredient.
For background information about our medicine factsheets, including the references used to produce them, click here.