PregabalinIn the Treatment of Postherpetic Neuralgia

▲ Pregabalin is the pharmacologically active S-enantiomer of 3-aminomethyl-5-methyl-hexanoic acid. It has a similar pharmacological profile to that of its developmental predecessor gabapentin, but had greater analgesic activity in rodent models of neuropathic pain.▲ Pregabalin is thought to act by reducing the excessive release of several excitatory neurotransmitters by binding to the α2-δ protein subunit of voltage-gated calcium channels.▲ Oral pregabalin 150–600 mg/day, administered in two or three divided doses, was significantly more effective than placebo in relieving pain and improving pain-related sleep interference in four randomized, double-blind, multicentre studies of 4–13 weeks’ duration in patients with postherpetic neuralgia (PHN).▲ Pregabalin achieved a faster onset of pain relief than placebo. The median times to the onset of pain relief with fixed and flexible doses of pregabalin were 1.5 and 3.5 days compared with <4 weeks with placebo.▲ Pregabalin was generally well tolerated when titrated over 1 week to fixed dosages (maximum 600 mg/day) in clinical trials in mostly elderly PHN patients. Adverse events were usually mild to moderate in severity.