Biobeschikbaarheid: beïnvloedende factoren

A drug’s bioavailability can be influenced by several factors.

Physicochemical properties, such as poor solubility, can decrease absorption. This limitation can be addressed using controlled-release or enteric-coated forms.

Drug stability in acidic gastric environments also impacts bioavailability. Acid-labile drugs should be administered as buffered or enteric-coated products to prevent degradation.

First-pass metabolism significantly reduces systemic drug levels. For example, propranolol undergoes extensive metabolism, reducing its systemic exposure. Meanwhile, prodrugs like valacyclovir metabolize into acyclovir, improving bioavailability.

Food also affects drug absorption. It enhances the systemic levels of isotretinoin but reduces didanosine bioavailability.

Lastly, drug–drug interactions can influence drug exposure via metabolizing enzymes and transporters. For example, enzyme inhibitors increase systemic levels by slowing metabolism, while enzyme inducers accelerate it, reducing plasma drug concentrations.