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Smoking cessation - Management
Drug interactions with smoking cessation
- Polycyclic aromatic hydrocarbons found in tobacco smoke are potent inducers of the hepatic enzymes CYP1A1 and CYP1A2.
- Levels of drugs metabolized by these enzymes are therefore lower in people who smoke, and will rise once the effect of induction wears off (about 1 week) after smoking cessation.
- During smoking cessation:
- Check whether the person is taking a medicine that interacts with smoking cessation.
- The most clinically important interactions are with theophylline, olanzapine, clozapine, caffeine, and warfarin.
- Monitor for adverse effects after smoking cessation.
- Adjust dose if necessary.
- Dose adjustment is not usually necessary in situations where there is temporary smoking cessation for 1 week or less (e.g. during an acute hospital stay).
[MHRA, 2009b]
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