FIG. 2.

A schematic diagram of drug disposition and the physiological factors that play roles in drug pharmacokinetics, such as transporters, metabolizing enzymes, protein binding, and gastric acid excretion (data from references 39, 143, 153, 164, 199, and 248). Any variation in genes encoding proteins involved in the disposition of drugs may have an impact on drug pharmacokinetics. NTCP, sodium-dependent taurocholate transporting polypeptide; BSEP, bile salt export pump; PGT, prostagladin transporter; cAMP, cyclic AMP; NAT, N-acetyltransferase; UGT, UDP-glucuronosyl transferase. The exact localizations and efflux directions of some of these transporters are still under investigation.