Anorgasmia in a patient with bipolar disorder type 1 treated with gabapentin

Gabapentin is a relatively new anticonvulsant indicated for adjunctive therapy in the treatment of partial seizures, with and without secondary generalization, in adults with epilepsy. Overall, it has a minimal side effect profile compared with other anticonvulsant agents. Postmarketing surveillance is needed to further delineate the spectrum of adverse events that may be experienced by patients treated with this medication. This is a case report of a 25-year-old man with a 10-year history of mood swings that progressively worsened and resulted in a suicide attempt 8 months before his first appointment. A diagnosis of bipolar disorder was established, and a clinical interview ruled out other mental disorders. The patient was administered gabapentin 300 mg/day, and the dose was titrated upward to 900 mg/day. A follow-up appointment revealed improved control of his bipolar symptoms. However, the patient reported that he could not have an orgasm during sexual intercourse. The medication was changed to valproic acid 250 mg three times daily. His bipolar symptoms remained under control and the anorgasmia resolved. This was maintained at the next follow-up appointment. The side effect profile and therapeutic monitoring requirements of gabapentin are favorable when compared with those of other anticonvulsant agents. However, because this agent is relatively new, especially for use in the treatment of bipolar disorder, a more thorough development of its side effect profile is needed. Observing, recording, and reporting atypical adverse events and side effects are critical to postmarketing surveillance and enhance the clinician's ability to make rational therapeutic decisions.