Can Viagra (sildenafil) be safely used in complete remission of acute lymphblastic leukaemia (ALL)

Fråga: "Can Viagra (sildenafil) be safely used in complete remission of acute lymphblastic leukaemia (ALL)?

The question concerns a man who has been in complete remission from ALL for three months and has erectile dysfunction. Leukemia is listed under "Cautions" for Viagra in the Swedish catalogue of approved drugs (FASS)."

Sammanfattning: Leukemia in complete remission should not be a risk factor of priapism. Priapism is a very rare complication of sildenafil use. However, the lowest effective dose should always be used.

Svar: Priapism has been described in haematological malignancy and is probably due to increased blood viscosity or "leukostasis" (1). However, viscosity should be normal in complete remission.

Priapism has only very rarely been associated with sildenafil. No case has been reported to the Swedish adverse drug reactions register (2) or in 10 clinical and 18 preclinical studies in over 5000 patients (3). However a Medline search revealed one case reported in 1999 (4) after 200mg and another two in 2000 (5,6), one of which was in a patient with sickle cell trait. Pfizer Inc made a report in 1998 about priapism and prolonged erection in association with Viagra. Of 32 reports, 14 were considered as priapism and at least 12 of these were associated with concomitant use of other drugs known to be able to cause priapism (7). Priapism has been reported to the WHO database in 183 cases, whereof 34 (all after 1998) from countries with a professional judgement of the relationship, but case histories are unavailable to us (8).

In 2002 several episodes of prolonged erection in two individuals on concomitant use of dihydrocodeine 30-60mg and sildenafil 100mg were observed (9). These erections detumesced spontaneously after 2-5 hours and are not reported to be painful and are so not to be considered as priapism.

Sildenafil has even been shown to relieve priapism in sickle crises (10). Interestingly, sildenafil has been shown to induce apoptosis in chronic lymphocytic leukaemia cells (11). 1 Fauci AS, Braunwald E, Isselbacher KJ, Wilson JD, Martin JB, Kasper DL, Hauser SL, Longon DL (eds), Harrison´s, Principles of internal medicine. 14th ed. New York: McGraw-Hill Inc; 1998. 2 Swedis (The Swedish Drug Information System) (cited 2003-02-17). 3 Morales A, Gingell C, Collins M, Wicker PA, Osterloh IH. Clinical safety of oral sildenafil citrate (Viagra) in the treatment of erectile dysfunction. Int J Impot Res 1998;10(2):69-73. 4 Aoyagi T, Hayakawa K, Miayaji K, Ishikawa H, Hata M. Sildenafil induced priapism. Bull Tokyo Dent Coll 1999;40(4):215-7 (Abstract). 5 Sur RL, Kane CJ. Sildenafil citrate-associated priapism. Urology 2000;55(6):950. 6 Kassim AA, Fabry ME, Nagel RL. Acute priapism associated with the use of sildenafil in a patient with sickle cell trait. Blood 2000 Mar 1;95(5):1878-9. 7 Rohde S. Sildenafil: Priapism, painful erection and prolonged erection. Worldwide Safety, Pfizer Inc. New York, NY. Aug 7, 1998. 8 Intdis (International Drug Information System): WHO:s adverse drug reactions database (cited 2003-02-21). 9 Goldmeier D. Prolonged erections produced by dihydrocodeine and sildenafil. BMJ 2002;324(7353):1555. 10 Bialecki ES, Bridges KR. Sildenafil relieves priapism in patients with sickle cell disease. Am J Med 2002 Aug 15;113(3):252. 11 Sarfati M, Mateo V, Baudet S, Rubio M, Fernandez C, Davi F, Binet JL, Delic J, Merle-Beral H. Sildenafil and vardenafil, types 5 and 6 phosphodiesterase inhibitors, induce caspase-dependent apoptosis of B-chronic lymphocytic leukemia cells. Blood 2003 Jan 1;101(1):265-9.