Basic pharmacokinetics and the potential effect of physical therapy interventions on pharmacokinetic variables.

Pharmacokinetics involves the factors that influence drug absorption, distribution, and elimination. Pharmacokinetic variables determine how a specific dose of a drug will eventually reach target tissues and exert a response. Various factors can influence normal pharmacokinetics, including exercise, application of physical agents, and massage. These interventions produce hemodynamic and other physiologic changes that can potentially alter drug disposition within the body. The magnitude and specific type of pharmacokinetic changes, however, are highly variable depending on the specific intervention and the drug in question. Physical therapy interventions seem to have the greatest potential to affect absorption and distribution of drugs that are administered by transdermal techniques or by subcutaneous and intramuscular injections. Research is needed to determine exactly how physical therapy interventions can affect the pharmacokinetics of various medications, and how the clinical effects of these medications are affected by altered drug disposition.