Nightly Dose of a PDE-5 Shows Potential as Cure for ED in Some Men

January 11, 2005
Internal Medicine World Report, January 2005,

Nightly Dose of a PDE-5 Shows Potential as Cure for ED in Some Men

By Charles Bankhead

San Francisco—A daily bedtime dose of a phosphodiesterase-5 (PDE-5) inhibitor may offer the potential to cure erectile dysfunction (ED) in a select patient population, results of a small German study presented at the American Urological Association meeting suggest.

Daily treatment with sildenafil (Viagra) for 12 months resulted in normal erectile function in >50% of a group of men with ED. All but 1 of the patients maintained erectile function during 6 months of follow up after the nightly sildenafil dose was discontinued.

“On the basis of these results, I think we can say that treatment with a PDE-5 inhibitor is able to cure erectile dysfunction in selected patients,” said Frank Sommer, MD, PhD, professor of urology and Chief of Andrology, University of Cologne. “Patient selection is important, but I am quite convinced that well-selected patients can achieve a cure.”

All of the patients had organic etiologies for erectile function or a mix of organic and psychogenic factors. The study did not include patients with pure psychogenic ED.

The concept of daily PDE-5 treatment at bedtime arose from the recognition that nocturnal erections occur at all ages and contribute to the maintenance of the integrity of smooth muscle cells in the corpora cavernosum, said Dr Sommer. In addition, short-term studies of nightly sildenafil have demonstrated significant improvement in nocturnal penile erections.

“Nightly treatment may help promote erectile function as a result of the drug’s beneficial effect on endothelial cells,” said Dr Sommer.

To evaluate the impact of long-term nightly sildenafil, investigators studied 84 men (mean age, 47.1 years) with ED of ³6 months’ duration. The patients were randomly assigned to receive 50 mg of sildenafil every night before bedtime or 50 to 00 mg of sildenafil, taken in the conventional on-demand manner. A third group of men received no treatment and served as a reference.

Treatment continued for 12 months. Primary efficacy measures were the erectile function domain score on the International Index of Erectile Function (IIEF) at 1 and 6 months after discontinuation of therapy and peak systolic velocity (PSV) of the penile arteries, assessed 1 month after discontinuation of therapy. An IIEF score of ³26 indicated normal erectile function.

After 12 months of treatment, 22 of 34 (64.7%) evaluable patients randomized to nightly sildenafil and 21 of 32 (65.6%) treated on demand had normal erectile function by IIEF criteria. In contrast, only 1 of 18 patients in the reference group had an IIEF score in the normal range. One month after discontinuation of sildenafil, 20 of 34 (58.8%) men on nightly therapy had IIEF scores of at least 26, compared with 3 of 32 in the on-demand group.

Peak systolic velocity of cavernosal arteries showed more improvement in patients treated with nightly sildenafil than either of the other 2 groups. At 13 months, PSV had increased from 29.4 to 38.9 cm/sec in patients on nightly therapy. In the on-demand group, mean PSV increased from 30.1 to 33.1 cm/sec. Peak systolic velocity decreased in the reference group from a mean of 27.6 cm/sec at baseline at 25.5 cm/sec at 13 months.

Among the patients on nightly therapy, 19 of 20 (95%) who had normal IIEF scores for erectile function at 1 month also had normal IIEF scores at 6 months. The 19 patients constituted 55.9% of the entire group.

Follow up will continue in the patients treated with nightly sildenafil to determine whether the impact on erectile function is durable without the need for additional medication.

“To our knowledge, this is the only study to date that has investigated the long-term effects of taking PDE-5 inhibitors on a daily basis,” said Dr Sommer. “We need longer follow up to make definite conclusions, but the results indicate that nightly sildenafil at bedtime can cause regression of erectile dysfunction and possible offer a cure for the condition.”

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