Tiagabine augmentation to fluvoxamine-risperidone combination in the treatment of obsessive-compulsive disorder

Despite the recent progress in the pharmacological treatment of obsessive-compulsive disorder (OCD)--especially with high doses of serotonin reuptake inhibitors, alone or in combination with low doses of antipsychotics--a non-negligible proportion of patients remains refractory to it. For these patients augmentation tactics with drugs from other chemical classes, including antiepileptic drugs, seems advisable. We report on the case of a female inpatient with OCD, whereby the adjunction of tiagabine, a selective GABA reuptake inhibitor at 15 mg/day, to a fluvoxamine (400 mg/day)-risperidone (1 mg/day) combination led to the patient's marked improvement as reflected in the reduction by almost 47% of her score on the Yale-Brown Obsessive Compulsive Scale. With respect to tiagabine's specifically anti-OCD mechanism of action, we note that enhanced inhibitory GABAergic neurotransmission slows down excitatory glutamatergic transmission in the cortico-striato-thalamic system, which presumably constitutes the core pathophysiological mechanism of OCD symptoms.