VIAGRA (Sildenafil citrate)

Viagra is an oral drug for male impotence, also known as erectiledysfunction (ED). It works by dilating blood vessels in the penis,allowing the inflow of blood needed for an erection.

VIAGRA, an oral therapy for erectile dysfunction, is the citrate salt of sildenafil, a selective inhibitor of cyclic guanosine monophosphate (cGMP)-specific phosphodiesterase type 5 (PDE5).
Sildenafil citrate is designated chemically as 1-[[3-(6,7-dihydro-1-methyl-7-oxo-3-propyl-1H-pyrazolo[4,3-d]pyrimidin-5-yl)-4-ethoxyphenyl]sulfonyl]-4-methylpiperazine citrate and has the following structural formula:

Sildenafil citrate is a white to off-white crystalline powder with a solubility of
3.5 mg/mL in water and a molecular weight of 666.7. VIAGRA (sildenafil citrate) is formulated as blue, film-coated rounded-diamond-shaped tablets equivalent to
25 mg, 50 mg and 100 mg of sildenafil for oral administration. In addition to the active ingredient, sildenafil citrate, each tablet contains the following inactive ingredients: microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin, and FD & C Blue #2 aluminum lake.

Important Safety Information

VIAGRA is indicated for the treatment of erectile dysfunction (ED).

The use of VIAGRA and organic nitrates in any form, at any time, is contraindicated.

Before treating ED, physicians should consider the impact of resuming sexual activity and the mild and transient vasodilatory effects of VIAGRA on blood pressure. Physicians should carefully consider whether patients with underlying cardiovascular disease or other more unusual conditions could be adversely affected by vasodilatory effects, especially in combination with sexual activity.

As there have been infrequent reports of prolonged erections lasting more than 4 hours or priapism with all ED treatments in this drug class, patients should be advised to seek immediate medical attention should these occur. Erections lasting longer than 6 hours can result in penile tissue damage and long-term loss of potency.

Use a starting dose of 25 mg for a patient who may have increased plasma levels (age >65, hepatic impairment, severe renal impairment, and concomitant use of potent CYP450 3A4 inhibitors). Patients taking ritonavir should not exceed 25 mg in a 48-hour period.

Patients with the following characteristics (recent serious cardiovascular events, hypotension or uncontrolled hypertension, or retinitis pigmentosa) did not participate in pre-approval clinical trials. In these patients, physicians should prescribe VIAGRA with caution.

Non-arteritic anterior ischemic optic neuropathy (NAION) has been reported rarely post-marketing in temporal association with the use of PDE5 inhibitors, including VIAGRA. It is not possible to determine if these events are related to PDE5 inhibitors or to other factors. Physicians should advise patients to stop use of PDE5 inhibitors, including VIAGRA, and seek medical attention in the event of sudden loss of vision.

Sudden decrease or loss of hearing has been reported in temporal association with the intake of PDE5 inhibitors, including VIAGRA. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors. Physicians should advise patients to stop taking PDE5 inhibitors, including VIAGRA, and seek prompt medical attention in the event of sudden decrease or loss of hearing.

In a controlled interaction study of VIAGRA and amlodipine, the mean additional reduction in supine blood pressure was 8 mm Hg systolic and 7 mm Hg diastolic.

Physicians should advise patients of the potential for PDE5 inhibitors, including VIAGRA, to augment the blood pressure lowering effect of alpha blockers and anti-hypertensive medications. In some patients concomitant administration of a PDE5 inhibitor and alpha blocker may lead to symptomatic hypotension. Patients should be stable on alpha-blocker therapy prior to initiating VIAGRA treatment and VIAGRA should be initiated at the lowest dose (25 mg).

Use of VIAGRA offers no protection against sexually transmitted diseases, including the human immunodeficiency virus (HIV); therefore, physicians should consider counseling their patients about protective measures.

The most common side effects of VIAGRA were headache (16%), flushing (10%), and dyspepsia (7%). Adverse events, including visual effects (3%), were generally transient and mild to moderate.