Composition

Each film coated tablet contains:
Sildenafil citrate ............................................................................. 35, 70, 140 mg
Equivalent to Sildenafil .................................................................. 25, 50, 100 mg
Inactive ingredients: Lactose, microcrystalline cellulose, croscarmellose sodium, magnesium stearate, colloidal silicon dioxide, talc purified.

Therapeutic Indications

Silden is indicated for the treatment of erectile dysfunction.

Dosage and Administration

For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, Silden may be taken anywhere from 4 hours to 0.5 hour before sexual activity.
Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. The maximum recommended dosing frequency is once per day.
The following factors are associated with increased plasma levels of sildenafil:
Age > 65 (40% increase in AUC), hepatic impairment (e.g. cirrhosis, 80%), severe renal impairment (creatinine clearance < 30 mL/min, 100%), and concomitant use of potent cytochrome P450 3A4 inhibitors [ketoconazole, itraconazole, erythromycin (182%), saquinavir (210%)].
Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered in these patients.
Ritonavir greatly increased the systemic level of sildenafil in a study of healthy, non-HIV infected volunteers (11-fold increase in AUC, see Drug Interactions). Based on these pharmacokinetic data, it is recommended not to exceed a maximum single dose of 25 mg of Silden in a 48 hour period.
Silden was shown to potentiate the hypotensive effects of nitrates and its administration in patients who use nitric oxide donors or nitrates in any form is therefore contraindicated.
When Silden is co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating Silden treatment and Silden should be initiated at the lowest dose (see Drug Interactions).

Contraindications

Consistent with its known effects on the nitric oxide/cGMP pathway (see Pharmacological Properties), Silden was shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using organic nitrates, either regularly and/or intermittently, in any form, is therefore contraindicated.
Silden is contraindicated in patients with a known hypersensitivity to any component of the tablet.

Warnings and Precautions

Warnings:
There is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease. Therefore, treatments for erectile dysfunction, including Silden, should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status.
Sildenafil 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), (see Pharmacological Properties: Pharmacodynamics). While this normally would be expected to be of little consequence in most patients, prior to prescribing Silden, 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.
Patients with the following underlying conditions can be particularly sensitive to the actions of vasodilators including Silden: those with left ventricular outflow obstruction (e.g. aortic stenosis, idiopathic hypertrophic subaortic stenosis) and those with severely impaired autonomic control of blood pressure.
There is no controlled clinical data on the safety or efficacy of sildenafil in the following groups; if Silden 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).
Prolonged erection greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently since market approval of sildenafil. 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 could result.
The concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC). If Silden is prescribed to patients taking ritonavir, caution should be used. Data from subjects exposed to high systemic levels of sildenafil are limited. Visual disturbances occurred more commonly at higher levels of sildenafil exposure. Decreased blood pressure, syncope, and prolonged erection were reported in some healthy volunteers exposed to high doses of sildenafil (200-800 mg). To decrease the chance of adverse events in patients taking ritonavir, a decrease in sildenafil dosage is recommended (see Drug Interactions, Undesirable Effects and Dosage and Administration)