Which analgesics are preferable in combination with Tryptizol (amitriptyline)?/nA 72-year-old man h

Fråga: Which analgesics are preferable in combination with Tryptizol (amitriptyline)?

A 72-year-old man has been treated for depression with amitriptyline 25 mg (1+0+3) daily throughout the last months. He is on no other medication. His dentist plans treatment for a painful tooth and suspects that the patient may have a low pain threshold. He wants to give the best possible pain relief, without using heavy analgesics. He also wants to avoid preparations containing acetylsalicylic acid, because the patient has previously had symptoms of gastritis.

Sammanfattning: In the present case, we suggest that paracetamol 1g x3-4 or if needed paracetamol in combination with codeine be used. If the effect is unsatisfactory the dose of codeine could be increased.

Svar: Drug interactions between amitriptyline and different analgesics have been described.

Dextropropoxyphene therapy can result in increased plasma concentrations of amitriptyline and especially its active metabolite nortriptyline, via inhibition of the metabolising enzyme CYP 2D6 (1).

The bioavailability of morphine given orally has been reported to be increased by amitriptyline (2).

The conversion of codeine to morphine is mediated by CYP 2D6. This conversion has been reported to be decreased by amitriptyline; thereby the pain relieving effect of codeine is decreased (3). Another possible choice could be tramadol (Nobligan).

No reports of interactions with regard to amitriptyline and paracetamol or acetylsalicylic acid have been found.

Finally, it could be noted that amitriptyline per se has beneficial effects in several pain conditions (4). 1 Jerling M, Bertilsson L, Sjöqvist F: The use of therapeutic drug monitoring data to document kinetic drug interactions: an example with amitriptyline and nortriptyline. Ther Drug Monit 1994; 16: 1-12 2 Ventafridda V, Ripamonti C, de Conno F, Bianchi M, Pazzuconi F, Panerai AE: Antidepressants increase bioavailability of morphine in cancer patients. Lancet 1987; I: 1204 3 The Swedish catalogue of approved medical products. 1996; page 1201 4 Magni G: The use of antidepressants in the treatment of chronic pain. A review of the current evidence. Drugs 1991; 42: 730-748