Increased use of antibiotics in patients treated with clozapine.

Clozapine has the potential to cause agranulocytosis and an association to an increased risk of infections has been suggested. Patients with an ICD-10 F20.x were identified from the Danish Central Psychiatric Research Registry and were linked to the national prescription database to identify schizophrenia patients treated with clozapine from 1996 to 2005(N=3374). Binomial regression and Cox proportional hazards models were used. An increased use of antibiotics was found RR=1.43, CI: 1.26-1.61, P<0.0001 and HR 1.14, 95% CI: 1.05-1.24, P=0.0025 with binomial regression and Cox proportional hazard model, respectively. The exact mechanism for the increased risk remains unknown, but the increased risk might be due to aspiration pneumonia caused by hypersalivation and the sedating properties of clozapine. The findings reported here should alert clinicians to be mindful of infectious processes as yet another possible somatic manifestation of clozapine treatment.