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Erectile dysfunction after therapy with metoprolol: the Hawthorne effect

Cocco G

Cardiology, 2009

114 participants

Abstract

AIMS: It is often assumed that beta-blockers, e.g. metoprolol (METO), induce erectile dysfunction (ED) in men. However, cardiovascular diseases can also induce ED and there is also the possibility that psychological factors, such as fear of the disease and side effects of the prescribed drug, may also induce ED. Thus, it is often assumed that beta-blockers induce ED in a large percentage of men, but this statement is not well validated and the role of the pharmacologic effect of METO per se on the occurrence of ED is largely unknown. To get an answer we selected 114 men (age 57 +/- 4.7 years) without ED but with newly diagnosed arterial hypertension, and who could be treated with METO.

METHODS: METO (100 mg/day) was given as a retard formulation. The hypertensive men were randomized into 3 groups. In group 1 patients were fully informed (they knew that the drug was METO and that it might induce ED). In group 2 patients were partially informed (they knew that the drug was METO, but were not informed that it might induce ED). In group 3 patients were not informed either about the drug used or about the possible occurrence of ED. The first phase of the study lasted 60 days. After 60 days the incidence of ED was 32% in group 1, 13% in group 2, and 8% in group 3 (p < 0.01). All patients with ED entered the second, cross-over, double-blind phase of the study. METO was continued at unchanged dosage, and tadalafil (20 mg) and a placebo were given to treat ED.

RESULTS: Both…

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Evidence Hub reads this as a randomized trial, done in people. Its evidence level is 2 of 5 (High · randomized trial). Randomized trials of a reasonable size are the strongest single-study design. Reported size: 114 participants or records.

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