The chapter delves into various routes of drug administration, including oral, rectal, suppositories, vaginal, urethral, transdermal, subcutaneous, intramuscular, intravenous, intra-artereal, intrathecal, epidural, and intradermal injections, discussing their advantages and targeted outcomes. It also covers the basics of pharmacokinetics and pharmacodynamics, explaining drug absorption, distribution, metabolism, and excretion processes in the body. Emphasizing the complexity of pharmacokinetics, the discussion touches on factors influencing drug interactions, individual variations, and the biochemical effects of drugs on the body.