The foregoing has necessitated the study of both adjunctive and alternative treatment options to lithium. A series of anticonvulsants have emerged as major mood stabilizing alternatives to lithium therapy for bipolar illness. Data on carbamazepine and valproate indicate that, although they appear to prevent manic and depressive episodes in patients inadequately responsive to lithium carbonate, they may not be sufficient for monotherapy. Two newer anticonvulsant agents, gabapentin and lamotrigine have shown promise in the treatment of patients with bipolar disorders. Case reports have described its potential psychiatric indications in bipolar disorder, panic disorder, generalized anxiety disorder and behavioral dyscontrol.
Therapeutic effect is noticed from within a week up to a month.
Gabapentin is generally well tolerated. The most common side effects are sedation, dizziness, unsteadiness, nystagmus, ataxia, fatigue, tremor and diplopia. Lamotrigine acts upon the voltage dependent sodium channels, resulting in inhibited release of the excitatory neurotransmitters glutamate and aspartate, and stabilization of the neuronal membranes. Early reports suggest that lamotrigine may be beneficial in patients with treatment resistant bipolar disorders, including mixed and rapid cycling illness. Its use in treating unipolar depression and anxiety disorders has not been extensively studied.