Pharmacokinetics and patient-controlled analgesia.

With patient control over dosage regimens as in PCA, the pharmacodynamic properties of the opioid analgesic agents emerge as being of greater importance than the pharmacokinetic properties in obtaining a salutary result. However, the prescription of opioid analgesic agents for PCA is more complex than for the same drugs under conventional control. There are major differences in the physicochemical, receptor selectivity and pharmacokinetic properties among opioid analgesic agents. Improved understanding of these differences, it is contended, can lead to more optimized strategies for the clinical management of pain whether under conventional or patient control. The impact of these properties on the components of the PCA prescription is discussed.