  The oral route is the most common choice for drug administration because of
convenience, low cost, and high patient compliance, but is also a complex
route. The rate of dissolution and gastric emptying of the dissolved active
pharmaceutical ingredient (API) into the duodenum is modulated by factors such
as gastric motility, but current in-vitro procedures for assessing drug
dissolution are limited in their ability to recapitulate this process. This is
particularly relevant for disease conditions, such as gastroparesis, that alter
the anatomy and/or physiology of the stomach. In this study we employ a
biomimetic in-silico simulator based on the realistic anatomy and morphology of
the stomach, to investigate the effect of body posture and stomach motility on
drug bioavailability. The simulations show that changes in posture can have a
significant (up to 83%) effect on the emptying rate of the API into the
duodenum. Similarly, reduction in antral contractility associated with
gastroparesis can also significantly reduce the dissolution of the pill as well
as emptying of the API into the duodenum. The simulations show that for an
equivalent motility index, reduction in gastric emptying due to neuropathic
gastroparesis is larger by a factor of about five compared to myopathic
gastroparesis.
