This document discusses pharmacokinetic drug interactions, including factors that influence them, mechanisms, and classifications. It describes several important interaction types like absorption interactions caused by complexation/adsorption or changes in GI pH. Distribution interactions can involve protein binding alterations, while metabolism interactions may be due to enzyme induction/inhibition. Excretion interactions can change active tubular secretion or urine pH. The effect of protein binding is explained using equations for volume of distribution and hepatic clearance. Cytochrome P450 inhibitors can increase drug bioavailability by inhibiting hepatic metabolism. In conclusion, recognizing interaction principles and vigilance when changing drugs can help identify harmful interactions.