In standard preclinical in vivo lifetime carcinogenicity studies, an unexpectedly high incidence of pancreatic acinar adenocarcinomas was identified in male, but not female, rats. (See PRECAUTIONS: Carcinogenesis, Mutagenesis, Impairment of Fertility.) The clinical significance of this finding is unknown. Clinical experience during gabapentin's premarketing development provides no direct means to assess its potential for inducing tumors in humans.
In clinical studies in adjunctive therapy in epilepsy comprising 2085 patient-years of exposure in patients > 12 years of age, new tumors were reported in 10 patients (2 breast, 3 brain, 2 lung, 1 adrenal, 1 non-Hodgkin's lymphoma, 1 endometrial carcinoma in situ), and preexisting tumors worsened in 11 patients (9 brain, 1 breast, 1 prostate) during or up to 2 years following discontinuation of Neurontin. Without knowledge of the background incidence and recurrence in a similar population not treated with Neurontin, it is impossible to know whether the incidence seen in this cohort is or is not affected by treatment.
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This medication should be used only when clearly needed during pregnancy. Discuss the risks and benefits with your doctor.
Gabapentin passes into breast milk. Because the effects of this drug on the nursing infant are unknown, consult your doctor before breast-feeding.