Gabapentin has not been evaluated for use during pregnancy in humans. Gabapentin is classified as FDA pregnancy category C. In animals, gabapentin has been fetotoxic during organogenesis at doses of 1-4 times the maximum recommended human dose on a mg/m2 basis. Delayed ossification of bones in the skull, limbs, and vertebrae were the predominant effects. An increased incidence of fetal loss was also noted. Based on the lack of protein binding and low molecular weight of the medication, placental transfer to the human fetus should be expected. A few cases of birth defects co-existing with gabapentin use in human pregnancy have been reported. In these cases, the women were also concomitantly taking other antiepileptic agents. An association of these birth defects with gabapentin is not conclusive. Gabapentin should be administered in pregnancy only if the benefit justifies the potential risks to the fetus. Physicians are advised to recommend that pregnant patients receiving gabapentin enroll in the North American Antiepileptic Drug (NAAED) Pregnancy Registry to provide information about the effects of in utero exposure to the drug. Patients must call 1-888-233-2334 to enroll in the registry.
Sometimes, putative medical adverse effects are regarded as controversial and generate heated discussions in society and lawsuits against drug manufacturers. One example is the recent controversy as to whether autism was linked to the MMR vaccine (or by thiomersal , a mercury -based preservative used in some vaccines ). No link has been found in several large studies, and despite removal of thimerosal from vaccines a decade ago the rate of autism has not decreased as would be expected if it had been the causative agent.