Clozapine: balancing safety with superior antipsychotic efficacy

Clozapine is often referred to as the gold standard for the treatment of schizophrenia and yet has also been described as the most underutilized treatment for schizophrenia supported by solid evidence-based medicine. In 2008, it was used to treat only 4.4% of patients with schizophrenia in the U.S., which is ~10-20% of those with approved indications for clozapine for which there is no alternative of equal efficacy. Its use is much higher in Scandinavian countries and China. The primary indications for clozapine are: 1) treatment-resistant schizophrenia or schizoaffective disorder, defined as persistent moderate to severe delusions or hallucinations despite two or more clinical trials with other antipsychotic drugs; and, 2) patients with schizophrenia or schizoaffective disorder who are at high risk for suicide. Concerns over a number of safety considerations are responsible for much of the underutilization of clozapine: 1) agranulocytosis; 2) metabolic side effects; and, 3) myocarditis. These side effects can be detected, prevented, minimized and treated, but there will be a very small number of fatalities. Nevertheless, clozapine has been found in two large epidemiologic studies to have the lowest mortality of any antipsychotic drug, mainly due to its very large effect to reduce the risk for suicide. Other reasons for limited use of clozapine include the extra effort entailed in monitoring white blood cell counts to detect granulocytopenia or agranulocytosis and, possibly, minimal efforts to market it now that it is largely generic. Awareness of the benefits and risks of clozapine is essential for increasing the use of this lifesaving agent.