Clozapine and tobacco

Q: A 64-year-old male with only a past history of depression and smoking is admitted to the hospital for severe community-acquired pneumonia (CAP). His only home medication is clozapine. His dose for clozapine should be? - select one

A) decreased

B) increased

Answer: A

Clozapine has a complex relationship with smoking. Smokers require almost a twofold increase in dose. Once they are stable on a higher-than-usual dose, it needs to be tapered down when in a nonsmoking environment.

Another important aspect of chronic clozapine use is the risk of agranulocytosis and its strong anticholinergic, sedative, cardiac, and hypotensive properties, so any agents with these characteristics should be used with care. 

#pharmacology

#psychiatry

References:

1. Tsuda Y, Saruwatari J, Yasui-Furukori N. Meta-analysis: the effects of smoking on the disposition of two commonly used antipsychotic agents, olanzapine and clozapine. BMJ Open 2014; 4:e004216.

2. McEvoy JP, Freudenreich O, Wilson WH. Smoking and therapeutic response to clozapine in patients with schizophrenia. Biol Psychiatry. 1999 Jul 1;46(1):125-9. doi: 10.1016/s0006-3223(98)00377-1. PMID: 10394482.

3. Zeng L, Lv H, Li J, Xue R, Liu X, Zhou C, Yu H. Cigarette smoking, coffee consumption, alcohol intake, and clozapine metabolism: A Mendelian randomization study. Front Psychiatry. 2022 Sep 29;13:1002235. doi: 10.3389/fpsyt.2022.1002235. PMID: 36245885; PMCID: PMC9559606.