Pregabalin Pharmacology and Its Relevance to Clinical Practice

Abstract

Pregabalin is a potent ligand for the alpha-2-delta subunit of voltage-gated calcium channels in the central nervous system that exhibits potent anticonvulsant, analgesic, and anxiolytic activity in a range of animal models. In addition, pregabalin has been shown to be a highly effective adjunctive therapy for partial seizures in clinical trials. Potent binding to the alpha-2-delta site reduces depolarization-induced calcium influx with a consequential modulation in excitatory neurotransmitter release. Pregabalin has no demonstrated effects on GABAergic mechanisms. Pregabalin demonstrates highly predictable and linear pharmacokinetics, a profile that makes it easy to use in clinical practice. Absorption is extensive, rapid, and proportional to dose. Time to maximal plasma concentration is approximately 1 h and steady state is achieved within 24-48 h. These characteristics reflect the observed onset of efficacy as early as day two in clinical trials. High bioavailability, a mean elimination half life (t(1/2)) of 6.3 h, and dose-proportional maximal plasma concentrations and total exposures predict a dose-response relationship in clinical practice and allow an effective starting dose of 150 mg/day in clinical practice without need for titration. Administration with food has no clinically relevant effect on the amount of pregabalin absorbed, providing for a dosing regimen uncomplicated by meals. Pregabalin does not bind to plasma proteins and is excreted virtually unchanged (<2% metabolism) by the kidneys. It is not subject to hepatic metabolism and does not induce or inhibit liver enzymes such as the cytochrome P450 system. Therefore, pregabalin is unlikely to cause, or be subject to, pharmacokinetic drug-drug interactions--an expectation that has been confirmed in clinical pharmacokinetic studies. However, dose adjustment may be necessary in patients with renal insufficiency. Thus, the pharmacological and pharmacokinetic profiles of pregabalin provide a predictable basis for its use in clinical practice.