Gabapentin abuse, and delirium tremens upon gabapentin withdrawal.

Sir: Gabapentin is one of a new generation of antiepileptic drugs widely used in recent years for a variety of indications, including epilepsy, neuropathic pain, migraine, and bipolar disorder. Although gabapentin is structurally analogous to γ-aminobutyric acid (GABA), it does not appear to affect GABA uptake or the GABA A or GABA B receptors. The basis of its anticonvulsant efficacy is unclear, but it may include inhibition of certain voltage-activated calcium channels. 1 Gaba-pentin increases brain GABA concentration and turnover. 2 Given this effect, it is perhaps not surprising that several studies have shown that gabapentin decreases alcohol withdrawal symptoms and may decrease cravings for alcohol in alcohol-dependent individuals. 3,4 While gabapentin has low abuse potential, abuse has been described in cocaine-dependent individuals. One report describes the abuse of gabapentin by snorting in 5 cocaine-dependent prison inmates. 5 Another case report describes a patient who reported reduced cocaine craving through the use of 600 to 1500 mg/day of gabapentin, prescribed for another individual. 6 A small number of reports have described withdrawal symptoms after discontinuation of gabapentin. Norton 7 described 3 cases of withdrawal in patients taking 4800, 3600, and 2400 mg/day: the first 2 developed elevated vital signs, confusion, agitation, and diaphoresis over a 2-to 3-day period, and the last developed irritability, headache, and diaphoresis over a 2-day period. A case similar to this last is also described by Drabkin and Calhoun. 8 Another patient taking 8000 mg/day developed status epilepticus 3 days after discontinuation of drug. 9 Yet another patient developed catatonia after gabapentin discontinuation. 10 This is notable because catatonia has been described after withdrawal from benzodiazepines, which also increase GABA transmission. Here we describe 2 patients who used larger doses of gabapentin than prescribed and who then developed a withdrawal syndrome similar to delirium tremens upon discontinuation of the drug. Case 1. Mr. A, a 33-year-old man, had a history of hepatitis C. He had a history of alcohol and other drug dependence, including a history of delirium tremens with alcohol withdrawal, but he had been using only cannabis, according to multiple reliable sources, for at least 6 months prior to the admission reported here. However, for at least that time he had been taking 3600 mg/day of gabapentin, twice his prescribed dose, because he felt the medication reduced his cravings for alcohol and made him feel calmer. Office staff routinely authorized early refills. He was …