Daily Dose of Apomorphine Efficacious in Treating Erectile Dysfunction

November 24, 2003

Yael Waknine

Nov. 24, 2003 — A daily dose of apomorphine sublingual (SL) proved efficacious in treating erectile dysfunction (ED) in 86% of 15 patients enrolled in an open-label, prospective pilot study published in the November issue of Urology. To date, studies have emphasized as-needed dosing in order to produce an erection firm enough for intercourse.

"[ED] is a widespread, age-related problem," write Salvatore Caruso, MD, and colleagues at the Department of Microbiological and Gynecological Sciences at the University of Catania School of Medicine in Catania, Italy. He emphasizes, "It has been forseen that by 2025 it will affect approximately 350 million men worldwide, with only 20% seeking treatment. According to our present knowledge, the quality of life, not only of patients, but also of their sexual partners, will be improved significantly with treatment."

The study enrolled 20 patients aged 27 to 46 years (mean age, 37.5 years) with a history of ED and a stable relationship of at least six months. Patients had a history of inability to attain and sustain an erection in at least 50% of attempts at intercourse over the last three months.

After a two-week screening period, 18 patients participated in a four-week as-required regimen of 2 mg apomorphine SL, escalated to 3 mg when appropriate after two weeks. Three patients (16.7%) benefited from this treatment modality ( P < .05). The nonresponding group of 15 patients continued with a daily regimen of 2 mg apomorphine SL for two weeks followed by 3 mg daily for two weeks. The 3 mg daily regimen was more effective for ED ( P < .02) and for each sexual domain scored with the International Index of Erectile Function questionnaire. Adverse events, as reported by three patients (23%) during the 3 mg regimen, were nausea, dizziness, and headache.

Although all patients were mildly hyperprolactinemic at the start of the study, prolactin levels returned to normal range during treatment with both 2 mg daily (12.2 ± 4.7 ng/mL), and 3 mg daily (10.6 ± 5.3 ng/mL) of apomorphine SL ( P < .05), while remaining elevated during the as-required dose-escalation regimen (24.3 ± 4.2 ng/mL). However, this does not prove a causal relationship. "A prolactin decrease in patients with mild hyperprolactinemia cannot directly produce, in our opinion, improved [erectile function]," the authors comment.

Increased dopaminergic tone in the paraventricular nucleus due to treatment with apomorphine SL may be directly responsible for the reduction in serum prolactin levels and also improvement in ED, the authors speculate. "Apomorphine, absorbed through the oral mucosa, acts as an erectogenic agent. Sublingual apomorphine is an effective and reasonable alternative for patients with ED."

Urology. 2003;62:922-927

Reviewed by Gary D. Vogin, MD

Yael Waknine is a freelance writer for Medscape.