Is there any risk of a clinically important interaction between Viagra (sildenafil) and Seroxat (pa

Fråga: Is there any risk of a clinically important interaction between Viagra (sildenafil) and Seroxat (paroxetine)?

A 29-year-old man with depression has been treated with paroxetine for several years. He is now suffering from erectile dysfunction and treatment with sildenafil is considered.

Sammanfattning: There is no information on drug interactions between sildenafil and paroxetine. Clinically important interactions between sildenafil and paroxetine are unlikely to occur.

Svar: A thorough literature search did not reveal any documentation on drug interactions between sildenafil and paroxetine.

In vitro studies have shown that sildenafil is mainly metabolised by the cytochrome P450 enzyme CYP3A4 and to a minor extent by CYP2C9 (1,2). Paroxetine is mainly metabolised by another isoenzyme CYP2D6 (3) and the risk of a metabolic interaction is low (4).

Two case reports concerning concomitant treatment with sildenafil and paroxetine are found in the literature (5,6). A 41-year-old woman (5) and a 36-year-old woman (6) were both treated with sildenafil for paroxetine induced sexual dysfunction. No signs of increased adverse reactions due to drug interactions were observed in either report.

There is no theoretical ground for a pharmacodynamic interaction on receptor or transduction levels. 1 Drugline no 14920 (year 1998)

2 Drugline no 17505 (year 2000)
3 Dollery C Sir, editor. Therapeutic drugs. 2nd ed. Edinburgh: Churchill Livingstone; 1999. p. P20-P25
4 Stockley IH. Drug interactions. 5th ed. London: The Pharmaceutical Press; 1999. p. 833
5 Ashton AK: Sildenafil treatment of paroxetine-induced anorgasmia in a woman. Am J Psychiatry 1999; 156: 800

6 Nurnberg HG, Lauriello J, Hensley PL, Parker LM, Keith SJ: Sildenafil for iatrogenic serotonergic antidepressant medication-induced sexual dysfunction in 4 patients. J Clin Psychiatry 1999; 60: 33-35