Cardiovascular risk and sildenafil
Section snippets
How sildenafil works
Sildenafil is an oral phosphodiesterase inhibitor that enhances erectile function through the same general pathway used by nature.6, 7, 8 Sildenafil requires sexual stimulation to occur in order for it to work. Sexual stimulation results in the release of nitric oxide from nerves and endothelial cells in the corpus cavernosum of the penis. Nitric oxide stimulates guanylate cyclase with the subsequent formation of cyclic guanosine monophosphate. Cyclic guanosine monophosphate is the substance
Efficacy of sildenafil in men with coronary artery disease
Is sildenafil effective in men with ischemic heart disease? Conti et al10 reported the results of a retrospective analysis of 357 men with stable chronic coronary artery disease not taking oral nitrates who were part of randomized, placebo-controlled trials testing the efficacy of sildenafil. Their mean age was 60 (placebo) and 62 (sildenafil) years and the mean duration of ED was about 5.5 years. Approximately half of the patients were on antihypertensives and a third were on antidiabetic
Frequency of cardiovascular events in placebo-controlled sildenafil trials
The issue of whether sildenafil could have an adverse effect on cardiovascular outcomes is best determined by placebo-controlled trials. Morales et al11 reported the incidence of serious cardiovascular events and MI among men who took part in 18 placebo-controlled studies. Serious cardiovascular events were listed as MI, angina, and coronary artery disease. The studies included 1,552 patients on placebo and 2,722 men on sildenafil. The duration of sildenafil use was up to 6 months. Serious
Spontaneous reports of death and cardiac events to the FDA
In November of 1998, the FDA placed information on its website on spontaneous reports of death and serious cardiovascular/cerebrovascular events among men who had used sildenafil.7, 14 Cases of death among men using sildenafil were seized upon by the media. It is worthwhile reviewing the advantages and disadvantages of this spontaneous reporting system and then putting the reports into perspective in relation to known rates of death and MI in a large population of men over a known duration of
Potential causes of death in men on sildenafil
How does one explain the observation that some deaths were temporally coupled to the use of sildenafil? One explanation is that some of these deaths were merely coincidental. A second is that they are the result of “reporting bias” (i.e., a person who takes a drug and experiences an adverse event soon afterward is more likely to associate the event with the drug. Therefore, he is more likely to report it than if he had taken the drug many hours or days before the event; neither situation either
Conclusion
Sildenafil is an effective oral medicine for ED. It improves erectile function in patients with ischemic heart disease and hypertension. In placebo-controlled trials including patients with ischemic heart disease and hypertension, the incidence of adverse cardiovascular events among patients on sildenafil was low and did not differ from placebo. Data from spontaneous reports of death among men using sildenafil have not demonstrated a signal that suggests an increased number of deaths above what
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Dr. Kloner is a speaker, consultant and researcher for Pfizer Inc.