ABSTRACT
This chapter considers some basic principles of clinical pharmacology and examines what drugs do to the body and what the body does to drugs. Many drugs act at receptors on target cell membranes and either activate the receptor or prevent its activation by a naturally occurring agonist. Most drugs are absorbed by passive diffusion, in that they pass through the lipid membrane of the mucosal cell walls passively. Once a drug reaches the systemic circulation it is distributed around the body. Many lipid soluble drugs are metabolized in the body. The kidney is responsible for elimination of most water soluble drugs or metabolites. The elimination of some drugs by the kidney may be slowed by renal disease, and dose reduction may be necessary. Renal function declines with age and slower excretion of a drug may lead to higher plasma concentrations. Single drug therapy is likely to be better than more complex regimes.
