Basic principles of pharmacologic action.

Individual differences in pharmacokinetic and pharmacodynamic factors can alter a patient's response to a drug. The health care team shares responsibility for providing optimal pharmacologic interventions. Nurses, however, spend more time with patients and are more likely to focus on the patient as an individual. These factors place them in a prime position to assess the patient's response to a drug. Nurses should always consider the probability that a change in a patient's physical condition or behavior could be caused by an adverse drug effect or, conversely, that a change in physiologic status could alter the patient's response to a drug. Before administering a new drug or a medication that is prescribed on an as-needed basis, one should consider whether the patient has disease-, nutrition-, age-, genetic-, or other-related factors that might alter pharmacokinetic or pharmacodynamic parameters. Even without knowing the myriad specific side effects attributed to a drug, an initial prediction of increased risk for adverse drug effects can be made by assessing the patients. Do they have a history of adverse drug reactions? Are they obese, malnourished, dehydrated, an alcoholic, or a smoker? Do they have hepatic or renal dysfunction? Is it possible that a loss of homeostatic reserve might affect the drug response? Application of the principles of pharmacokinetics and pharmacodynamics to nursing assessment can improve the outcome of drug therapy and decrease the incidence of adverse drug effects.