Gabapentin

Additional information

Pharmacokinetics and dosing

Population data analyses indicate that the pharmacokinetic parameters for men and women are similar [1, 2]. One small clinical trial evaluated the effect of patient’s sex on the pharmacokinetics of gabapentin (18 men, 18 women). Following a single 400 mg oral dose gabapentin, Cmax was about 25% higher for women than for men, probably due to a smaller volume of distribution in women, as a result of their generally smaller size. However, the sex difference in Cmax values is not considered to be clinically important. The apparent elimination rate constant declined with increasing age for women but did not reach significance in relation with age for men. Since the relation between the apparent oral clearance and age was similar for men and women, the sex difference in relation between apparent elimination rate constant and age may be due to a sex-related difference in the relation between volume of distribution and age [3]. No sex differentiation in dosing has been recommended by the pharmaceutical company [4]. Individual dose-titration is recommended for all indications in both men and women.

Effects

No published studies with a clinically relevant sex analysis regarding the effects of gabapentin in epilepsy or neuropathic pain have been found. Estimates of response to gabapentin in epilepsy derived from clinical trials (398 men, 307 women) indicate no appearant sex differences [1].

Adverse effects

According to the pharmaceutical company, adverse effects were more common in men than in women [2], but studies with a clinically relevant sex analysis regarding adverse effects of gabapentin have not been published.

Reproductive health issues

Regarding teratogenic aspects, please consult the Drugs and Birth Defects Database (in Swedish, Janusmed fosterpåverkan).