Letters to the Editor
Anorgasmia and Withdrawal Syndrome in a Woman Taking Gabapentin
Dear Editor:
Gabapentin is used to manage many psychiatric conditions, notably anxiety and bipolar disorders (BDs). However, clinical studies to support this practice are few (1).
Four case reports describe anorgasmia in men taking gabapentin but none describe anorgasmia in women (2–5). In these cases, desire and arousal were maintained; orgasm returned after the patients either stopped taking gabapentin or reduced the dosage to less than 1000 mg daily.
A gabapentin-withdrawal syndrome that is similar to benzodiazepine or alcohol withdrawal has been described. It includes tachycardia, diaphoresis, headache, and gastrointestinal cramps (6). Although gabapentin’s mode of action is unknown, the similarity in withdrawal symptoms has been put forward as indirect evidence that gabapentin acts at the GABA receptor, where alcohol and benzodiazepines are known to act.
We describe anorgasmia in a woman taking gabapentin. When gabapentin was tapered, she had symptoms similar to the described withdrawal syndrome. Interestingly, her anorgasmia resolved in the same 24-hour period within which these withdrawal symptoms ended. We briefly discuss the implications of these occurrences.
Case Report
A 35-year-old married woman was referred to an ambulatory psychiatry clinic for assessment of a mood disorder for which her general practitioner had prescribed various antidepressants over a 2-year period, with no sustained benefit.
A history review revealed hypomanic episodes. She was diagnosed with BD II, and gabapentin treatment was started. She was taking no other medications. Gabapentin was titrated over a 2-month period to a daily dosage of 3600 mg. On this medication, her hypomania symptoms improved moderately. Six months after starting gabapentin, the patient presented with depression symptoms. Lithium was added, and therapeutic blood levels were achieved within 1 month at a dosage of 900 mg daily. At this dosage, her depression resolved. Once euthymic, she reported anorgasmia that had begun 3 to 4 months previously (that is, well before lithium therapy). She described having been able to reach orgasm easily and frequently, prior to starting gabapentin. While taking gabapentin, her libido and arousal had remained at her usual high pretreatment level.
In light of the case reports of anorgasmia in men taking gabapentin, we discontinued this medication over a 6-week period. During discontinuation, the patient spontaneously reported diaphoresis, tremulousness, and gastrointestinal cramps. These symptoms continued for 8 days after the last gabapentin dosage. Anorgasmia persisted until 9 days after her last gabapentin dosage. Thus, her discontinuation symptoms and anorgasmia resolved within 24 hours of each other.
Discussion
As stated earlier, this is the first case report of a woman with gabapentin-related anorgasmia. It may be an idiosyncratic reaction in this patient, but we speculate that this symptom may in fact be more common than previously recognized in both women and men taking gabapentin. We do not have a physiological explanation for this symptom: gabapentin’s mechanism of action is still unclear.
Further, in this patient, both anorgasmia and withdrawal symptoms resolved within 24 hours of each other, 8 to 9 days after the last dosage of gabapentin. Because gabapentin’s mechanism of action is not known, we do not know whether this temporal relation is coincidental.
Until these phenomena with regard to gabapentin are more clearly understood, it seems prudent to inquire about sexual dysfunction in patients taking this medication and to advise patients discontinuing gabapentin about possible withdrawal symptoms.
References
1. Ghaemi SN, Gaughan S. Novel anticonvulsants: a new generation of mood stabilisers? Harv Rev Psychiatry 2000;8(1):1–7.
2. Labbate AL, Rubey RN. Gabapentin-induced ejaculatory failure and anorgasmia. Am J Psychiatry 1999;156:972.
3. Clark D, Elliot J. Gabapentin-induced anorgasmia. Neurology 1999;53:2209.
4. Montes JM, Ferrando L. Gabapentin-induced anorgasmia as a cause of non-compliance in a bipolar patient. Bipolar Disorders 2001;3:52.
5. Brannon GE, Rolland PD. Anorgasmia in a patient with bipolar disorder type I treated with gabapentin. J Clin Psychopharmacol 2000;20:379–81.
6. Norton JW. Gabapentin withdrawal syndrome. Clin Neuropharmacol 2001;24:245–6.
Rodney Drabkin, MB,ChB, CCFP
Laura Calhoun, MD, FRCP
Winnipeg, Manitoba
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