Orally administered drugs undergo four stages of absorption, distribution, metabolism, and excretion in the body. However, before being absorbed into the body, orally administered drugs contact with gut microbiota, which catalyze their metabolic reactions such as reduction, hydroxylation (including deconjugation), dehydrogenation, acetylation, etc. Although these metabolic reactions typically inactivate drugs (ranitidine, digoxin, and amlodipine), some activate them (sulfasalazine). The composition and quantity of gut microbiota are variable across individuals and fluctuated by gut microbiota modulators such as diets, drugs (antibiotics), probiotics, prebiotics, pathogen infections, and stressors. Gut microbiota-involved metabolisms of drugs in the gastrointestinal tract are dependent on the composition and quantity of gut microbiota. Therefore, the bioavailability of orally administered drugs is significantly affected by gut microbiota modulators. This review describes gut microbiota modulator-drug interactions.
Keywords: Drug; bioavailability; gut microbiota; gut microbiota modulator; metabolism.