There is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease. Therefore, treatments for erectile dysfunction, including Viagra (Sildenafil citrate), should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status.

Viagra (Sildenafil citrate) has systemic vasodilatory properties that resulted in transient decreases in supine blood pressure in healthy volunteers (mean maximum decrease of 8.4/5.5 mmHg). While this normally would be expected to be of little consequence in most patients, prior to prescribing Viagra (Sildenafil citrate), physicians should carefully consider whether their patients with underlying cardiovascular disease could be affected adversely by such vasodilatory effects, especially in combination with sexual activity.

There is no controlled clinical data on the safety or efficacy of Viagra (Sildenafil citrate) in the following groups; if prescribed, this should be done with caution.

• Patients who have suffered a myocardial infarction, stroke, or life-threatening arrhythmia within the last 6 months.
• Patients with resting hypotension (BP <90/50) or hypertension (BP >170/110).
• Patients with cardiac failure or coronary artery disease causing unstable angina.
• Patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases).

General

The evaluation of erectile dysfunction should include a determination of potential underlying causes and the identification of appropriate treatment following a complete medical assessment.

Before prescribing Viagra (Sildenafil citrate), it is important to note the following:

Patients on multiple antihypertensive medications were included in the pivotal clinical trials for Viagra (Sildenafil citrate). In a separate drug interaction study, when amlodipine, 5 mg or 10 mg, and Viagra (Sildenafil citrate), 100 mg were orally administered concomitantly to hypertensive patients mean additional blood pressure reduction of 8 mmHg systolic and 7 mmHg diastolic were noted. Controlled studies of drug interactions between sildenafil citrate and other antihypertensive medications have not been performed.

The safety of Viagra (Sildenafil citrate) is unknown in patients with bleeding disorders and patients with active peptic ulceration.

Viagra (Sildenafil citrate) should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernosal fibrosis or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anemia, multiple myeloma, or leukemia).

The safety and efficacy of combinations of Viagra (Sildenafil citrate) with other treatments for erectile dysfunction have not been studied. Therefore, the use of such combinations is not recommended.

In humans, Viagra (Sildenafil citrate) has no effect on bleeding time when taken alone or with aspirin. In vitro studies with human platelets indicate that Viagra (Sildenafil citrate) potentiates the antiaggregatory effect of sodium nitroprusside (a nitric oxide donor). The combination of heparin and Viagra (Sildenafil citrate) had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans.

Physicians should discuss with patients the contraindication of Viagra (Sildenafil citrate) with regular and/or intermittent use of organic nitrates. Physicians should discuss with patients the potential cardiac risk of sexual activity in patients with preexisting cardiovascular risk factors. Patients who experience symptoms (e.g., angina pectoris, dizziness, nausea) upon initiation of sexual activity should be advised to refrain from further activity and should discuss the episode with their physician. Physicians should warn patients that prolonged erections greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently since market approval of sildenafil citrate. In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency may result. The use of sildenafil citrate offers no protection against sexually transmitted diseases. Counseling of patients about the protective measures necessary to guard against sexually transmitted diseases, including the Human Immunodeficiency Virus (HIV), may be considered.

Healthy elderly volunteers (65 years or over) had a reduced clearance of Viagra (Sildenafil citrate). Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered .