What drug interactions should I be aware of with tricyclic antidepressants?
• For a complete list of interactions, consult the relevant Summary of Product Characteristics (SPC) or consult the British National Formulary. • Tricyclic antidepressants interact with a number of drugs including: • Analgesics: increased risk of central nervous system toxicity with tramadol (e.g. convulsion). • Anti-arrhythmics: increased risk of ventricular arrhythmias with drugs which prolong the QT interval (e.g. disopyramide, quinidine). Avoid concomitant use with amiodarone. • Antidepressants: • Monoamine oxide inhibitors (MAOIs): avoid concomitant use with an MAOI. Allow a minimum of 14 days (or 21 days in the case of imipramine and clomipramine) between discontinuing an MAOI and starting a tricyclic antidepressant. After this time, amitriptyline should be used cautiously and the dose increased gradually. • Fluoxetine can inhibit the metabolism of a number of tricyclic antidepressants, leading to increased plasma levels and toxicity. Adjustment of the antidepressant dose may be
