Thirty months after its launch in the United States, Sildenafil (sold under brand name Viagra in America) has finally received the government's green signal to enter the Indian market (sold various brand names e.g. Penegra, Edegra, etc.). Unfortunately the media created unnecessary hype, and hope, by selectively focussing on the advantages of this drug in erectile dysfunction, ignoring its serious side-effects, particularly in patients of cardiovascular diseases. Let us look at the untold side of sildenafil's story.

In the period April 1998 to February 2000, a total of 1,473 major adverse events in persons on sildenafil were reported to the United States Food and Drug Administration (USFDA). 522 people died, the majority due to cardiovascular causes. A majority of deaths (70%) were associated with the standard sildenafil dose of 50mg. Two-thirds of deaths occurred within 4-5 hours of consuming sildenafil. A majority of people who died were below 65 years of age with no cardiac risk factors (diabetes, hypertension, high cholesterol or smoking). In the United States, adverse drug reactions are reported on a voluntary basis. Therefore, there may be an element of under-reporting, the magnitude of which is not known.

It is well known that the use of nitrates along with sildenafil can lead to serious cardio-vascular events with fatal outcome. Of the 90 persons who were on nitrates and consumed sildenafil, 68% died. Interestingly, a large number of deaths (522) actually occurred in people who were not taking nitrates. Apparently there are some susceptible individuals in whom nitrates are not necessary to unmask the harmful effect of sildenafil. The problem is that there is no known method to identify such individuals at risk.

One thing is, however, crystal clear. A person's heart should be healthy enough to handle the extra strain of having sex after taking sildenafil. Cardiac "expenditure" during sexual intercourse varies depending upon the type of activity. Healthy males, with their usual female partners, achieve a peak rate of 110 heart beats per minute and consume 2.5 Metabolic Equivalents (METS) during "woman-on-top" coitus and 127 heart beats per minute and 3.3 METS during "man-on-top" coitus. Some individuals even attain a rate of, as high as 185 heart beats per minute. Therefore the stress of sex on cardiac functions cannot be compared with "climbing 1 or 2 flights of stairs."

The dilemma faced by doctors is that the very people with cardiovascular conditions where sildenafil needs to be avoided are the ones who suffer from erectile dysfunctions! So what do we do? It is best to avoid the use of sildenafil in:

Persons taking any chronic nitrate drug therapy e.g. isosorbide dinitrate (e.g. Sorbitrate), isosorbide-5-mononitrate (e.g. Monotrate), pentaerythritol tetranitrate, glyceryl trinitrate or those using short-acting nitrate containing medications including inhaled forms (e.g. amyl nitrate or nitrite). This group must not be given sildenafil due to the risk of developing potentially life-threatening hypotension.

Patients who have suffered from myocardial infarction or stroke within the last six months.

Patients with coronary artery disease who are not on nitrates. These people are potential users of nitrates in emergency.

Patients with uncontrolled hypertension.

Patients on multi-drug therapy for hypertension.

Patients of congestive heart failure and borderline low blood pressure. Sildenafil has not been extensively investigated in such situations.

All patients taking nitrates, even if they do not ask for sildenafil, should be informed about the dangers of nitrate-sildenafil interaction. Apart from cardiac causes, there are other situations where sildenafil is to be avoided such as co-administration of erythromycin (which can increase plasma levels of sildenafil by +182%), cimetidine, ticlodipine, dipyridamole and persons with retinal disorders, liver or kidney diseases.