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Bipolar disorder - Management
What are the drug interactions of antipsychotics?
- Atypical antipsychotics such as quetiapine, olanzapine, and risperidone have not generally been associated with clinically significant prolongation of the QT interval. However, they should be used with care if prescribed with other drugs that increase the QT interval (e.g. antiarrhythmics).
- There is an increased risk of central nervous system toxicity when antipsychotics are given with sibutramine, and the manufacturer of sibutramine advises against concomitant use.
- The plasma concentration of quetiapine may be increased by fluconazole, itraconazole, and ketoconazole, so the dose of quetiapine should be reduced.
- Smoking induces the metabolism of olanzapine and clozapine. If the person stops smoking, monitor for increased adverse effects and seek advice about dose adjustment if necessary.
[BNF 56, 2008; MHRA, 2009b]
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