Gastrointestinal, Pulmonary Illnesses Top List in Hospitalized Patients on Clozapine, Study Finds

When prescribing clozapine—the only antipsychotic that has been FDA-approved for treatment-resistant schizophrenia—clinicians have been required by an FDA boxed warning to closely monitor patients’ blood to reduce the risk agranulocytosis and other adverse events. However, a study published in Psychosomatics now suggests pulmonary and gastrointestinal illnesses may be the most likely reason for patients prescribed clozapine to be hospitalized.

These findings are not unexpected, wrote Robert Morgan, M.D., Ph.D. (pictured above), and colleagues from the Mayo Clinic in Minnesota, “given that clozapine-related neutropenia and myocarditis have the highest incidence within several months after first exposure and are likely to be discovered through vigilant monitoring. Discovery then allows for early clozapine discontinuation and resolution of the adverse event, potentially avoiding medical hospitalization.”

The researchers conducted a retrospective chart review of patients with schizophrenia or schizoaffective disorder who were taking clozapine and admitted to an inpatient medical unit at the Mayo Clinic for nonpsychiatric illness between January 1, 2003, and August 1, 2005. A total of 104 adults aged 18 and older were included in the analysis. They were admitted into the hospital a total of 248 times, and the mean clozapine dose prescribed at the index admission was 407.2 mg.

Pulmonary illness and gastrointestinal illness were the most common reasons for hospitalizations at 32.2% and 19.8%, respectively. The most common pulmonary diagnosis was pneumonia, accounting for 58% of pulmonary admissions. The most common reason for gastrointestinal diagnosis was hypomotility, at 61.2%. The authors noted that clozapine was discontinued due to neutropenia in two patients; there were no patients admitted for myocarditis.

Psychiatric consultation was obtained in 25% of the hospitalizations, “most frequently for ‘clozapine management,’ retitration recommendations, or possible clozapine toxicity. Clozapine dosage adjustment infrequently occurred, and complete discontinuation was rare,” they wrote.

“While these findings are not indicative of causal relationships, an increased awareness of medical problems that lead to hospitalization in patients prescribed clozapine is required among all disciplines,” the authors concluded. 

For related information, see the Psychiatric News article “Why Won’t Clinicians Use Clozapine Despite Proven Superiority?” 

(Photo Courtesy of Mayo Clinic, Rochester)