Smokers need higher doses of antipsychotics

With smoking prevalence up to three times higher in patients with psychiatric disorders compared to the general population, Japanese researchers said the findings could be used to change current clinical practice.

The meta-analysis looked at data from more than 1200 cases where patients were prescribed olanzapine or clozapine and smoking status was recorded. They found that for both drugs, blood concentration to dose ratios were significantly lower in smokers compared to non-smokers. 

The authors said the daily doses of olanzapine and clozapine should be reduced by 30% and 50% respectively in non-smokers to achieve equivalent concentrations to the smokers. 

“We estimated that if 10 and 20mg/day of olanzapine would be administered to smokers, about 7 and 14mg/day respectively should be administered to non-smokers,” they said. 

For clozapine, which was affected more severely by cigarette smoke, the authors reported