It exerts its effect through α2δ type 1 subunit of calcium channels. It causes decrease in transport of calcium across the channel and thereby decrease in the release of transmitters (glutamate, noradrenaline), thus decreasing the neuronal excitability. Pregabalin increases the interneuronal concentration of γ-aminobutyric acid. Both are well absorbed orally (bioavailability: 60 %) and are weakly bound to proteins (<3 %) and are excreted in urine. Gabapentin is useful for postherpetic neuralgia, painful diabetic neuropathy (NNT 2.9), orofacial pain, fibromyalgia and Guillain-Barre syndrome. Pregabalin has shown efficacy for postherpetic neuralgia and painful diabetic neuralgia. Most common side effects seen are drowsiness, dizziness, weight gain, dry mouth and constipation (NNH 2.5). Gabapentin is started at 100 mg/day and increased on a weekly basis to a maximum of 3,600 mg/day. Pregabalin is started at 150 mg/day and increased to a maximum of 300 mg/day over a period of 1–2 weeks. Pregabalin has advantages over gabapentin in that it is administered twice daily (gabapentin, thrice daily), is easily titratable and has an early onset (gabapentin, days to weeks).