Are there any know interactions between amitriptyline and buspirone?/nA woman with eating disorder,

Fråga: Are there any know interactions between amitriptyline and buspirone?

A woman with eating disorder, depression, anxiety and sleep disturbance is treated with amitriptyline (Tryptizol). The physician wants to add buspirone (Buspar) to her treatment.

Sammanfattning: No documentation on possible interactions between buspirone and amitriptyline was found.

Svar: A thourough literature search gave no documentation concerning an interaction between buspirone and amitriptyline. Buspirone is metabolised by CYP3A4 (1,2) and amitriptyline is metabolised by CYP2D6 and CYP1A2 (2).

Amitriptyline is a tricyclic antidepressant which inhibit reuptake of noradrenaline and 5-HT (serotonin). Buspirone is an anxiolytic drug. It is a partial agonist of postsynaptic 5-HT1A receptors and a full agonist of presynaptic 5-HT1A autoreceptors. Buspirone has a direct antagonist effect on the presynaptic dopamine receptor (2,3) and does not interact with noradrenergic receptor (2).

Theoretically a pharmacodynamic interaction leading to increased risk of serotonin syndrom might be possible. However, there are no reports concerning serotonin syndrom following this combination. One case of serotonin syndrom has been described when buspirone was combined with citalopram, which is a selective serotonin re-uptake inhibitor (4).

Co-administration of buspirone and amitriptyline do not alter the disposition of these drugs (4). 1 Drugline no 15933 (year 1999) 2 Drugline no 15457 (year 1999) 3 Dollery C Sir, editor. Therapeutic drugs. 2nd ed. Edinburgh: Churchill Livingstone; 1999 4 Stockley IH. Drug interactions. 6th ed. London: The Pharmaceutical Press; 2002. p. 713. 5 Gammans RE, Mayol RF, Labudde JA. Metabolism and disposition of buspirone. Am J Med 1986;80(Suppl 3B):41-51.