Similar effects on blood pressure were noted with 25 mg, 50 mg and 100 mg doses of sildenafil, therefore the effects are not related to dose or plasma levels within this dosage range.

In case of emergency/overdose

No evidence of teratogenicity, embryotoxicity, or fetotoxicity was observed in pregnant rats or rabbits dosed with sildenafil 200 mg/kg/day during organogenesis, a level that is, on a mg/m2 basis, 32- and 65-times, respectively, the recommended human dose (RHD) of 20 mg three times a day. In a rat pre- and postnatal development study, the no-observed-adverse-effect dose was 30 mg/kg/day (equivalent to 5-times the RHD on a mg/m2 basis). Limited published data from a case report describe the presence of sildenafil and its active metabolite in human milk. There is insufficient information about the effects of sildenafil on the breastfed infant and no information on the effects of sildenafil on milk production. Limited clinical data during lactation preclude a clear determination of the risk of REVATIO to an infant during lactation.

Revatio for Oral Suspension

In a randomized, double-blind, multi-center, placebo-controlled, parallel-group, dose-ranging study, 234 patients with PAH, aged 1 to 17 years, body weight greater than or equal to 8 kg, were randomized, on the basis of body weight, to three dose levels of REVATIO, or placebo, for 16 weeks of treatment. Most patients had mild to moderate symptoms at baseline: WHO Functional Class I (32%), II (51%), III (15%), or IV (0.4%). One-third of patients had primary PAH; two-thirds had secondary PAH (systemic-to-pulmonary shunt in 37%; surgical repair in 30%). Sixty-two percent of patients were female. Drug or placebo was administered three times a day. Larger effects were recorded among patients receiving concomitant nitrates [see Contraindications (4)].

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Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on ECG. After chronic dosing of 80 mg three times a day to patients with PAH, no clinically relevant effects on ECG were reported. After chronic dosing of 80 mg three times a day sildenafil to healthy volunteers, the largest mean change from baseline in supine systolic and supine diastolic blood pressures was a decrease of 9.0 mmHg and 8.4 mmHg, respectively.

Chemical synthesis

Clinical studies of REVATIO did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects. Other reported clinical experience has not identified differences in responses between the elderly and younger patients. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy [see Clinical Pharmacology (12.3)]. No dose adjustment for mild to moderate impairment is required. Severe impairment has not been studied [see Clinical Pharmacology (12.3)].

What should I do if I miss a dose of sildenafil?

No dose adjustment is required (including severe impairment CLcr < 30 mL/min) [see Clinical Pharmacology (12.3)]. In studies with healthy volunteers of single sildenafil for women doses up to 800 mg, adverse events were similar to those seen at lower doses but rates and severities were increased. Sildenafil is also marketed as VIAGRA® for erectile dysfunction. REVATIO (sildenafil) Tablets: REVATIO is formulated as white, film-coated round tablets for oral administration. Each tablet contains sildenafil citrate equivalent to 20 mg of sildenafil. After chronic dosing of 80 mg three times a day sildenafil to patients with systemic hypertension, the mean change from baseline in systolic and diastolic blood pressures was a decrease of 9.4 mmHg and 9.1 mmHg, respectively.

Adverse effects

Sildenafil is only about 10-fold as potent for PDE-5 compared to PDE6, an enzyme found in the retina and involved in the phototransduction pathway of the retina. This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels [see Clinical Pharmacology (12.2)]. In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE-5 is also found in other tissues including vascular and visceral smooth muscle and in platelets. The inhibition of PDE-5 in these tissues by sildenafil may be the basis for the enhanced platelet anti-aggregatory activity of nitric oxide observed in vitro, and the mild peripheral arterial-venous dilatation in vivo. Patients on all REVATIO doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [Study 1 in Clinical Studies (14)]. After chronic dosing of 80 mg three times a day sildenafil to patients with PAH, lesser reductions than above in systolic and diastolic blood pressures were observed (a decrease in both of 2 mmHg).

Storage Condition	Details	Notes
Temperature	Store below 25°C (77°F)	Avoid heat and humidity
Light Exposure	Keep in original container, shield from light	Protect from sunlight
Shelf Life	Typically 2–3 years	Check expiry date before use

At single oral doses of 100 mg and 200 mg, transient dose-related impairment of color discrimination (blue/green) was detected using the Farnsworth-Munsell 100-hue test, with peak effects near the time of peak plasma levels. An evaluation of visual function at doses up to 200 mg revealed no effects of REVATIO on visual acuity, intraocular pressure, or pupillometry. REVATIO is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25–63%). When REVATIO is taken with a high-fat meal, the rate of absorption is reduced, with a mean delay in Tmax of 60 minutes and a mean reduction in Cmax of 29%. Bioequivalence was established between the 20 mg tablet and the 10 mg/mL oral suspension when administered as a 20 mg single oral dose of sildenafil (as citrate).

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• It is FDA-approved for the treatment of pulmonary arterial hypertension as well.
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• Sildenafil may interact with certain medications, such as alpha-blockers.
• Dosage adjustment might be necessary based on individual health conditions.
• It typically takes effect within 30 minutes to 1 hour after intake.
• Avoid alcohol consumption when taking sildenafil to minimize side effects.
• Store the medication at room temperature away from moisture and heat.

Sildenafil is cleared predominantly by the CYP3A (major route) and cytochrome P450 2C9 (CYP2C9, minor route) hepatic microsomal isoenzymes.

How should this medicine be used?

The primary objective of the study was to assess the effect of REVATIO on exercise capacity as measured by cardiopulmonary exercise testing in pediatric patients developmentally able to perform the test (n = 115). Administration of REVATIO did not result in a statistically significant improvement in exercise capacity in those patients. No patients died during the 16-week controlled study. After completing the 16-week controlled study, a patient originally randomized to REVATIO remained on his/her dose of REVATIO or, if originally randomized to placebo, was randomized to low-, medium-, or high-dose REVATIO. After all patients completed 16 weeks of follow-up in the controlled study, the blind was broken and doses were adjusted as clinically indicated.

What are the serious side effects of sildenafil?

Patients treated with sildenafil were followed for a median of 4.6 years (range 2 days to 8.6 years). Mortality during the long-term study, by originally assigned dose, is shown in Figure 6: During the study, there were 42 reported deaths, with 37 of these deaths reported prior to a decision to titrate subjects to a lower dosage because of a finding of increased mortality with increasing REVATIO doses. For the survival analysis which included 37 deaths, the hazard ratio for high dose compared to low dose was 3.9, p=0.007. Causes of death were typical of patients with PAH. Use of REVATIO, particularly chronic use, is not recommended in children. The major circulating metabolite results from N-desmethylation of sildenafil, and is, itself, further metabolized.

Non-medical use

Data on other hemodynamic measures for the REVATIO 20 mg three times a day and placebo dosing regimens is displayed in Table 3. The relationship between these effects sildenafil 100mg hexal and improvements in 6-minute walk distance is unknown. In another study evaluating lower doses of sildenafil 1 mg, 5 mg and 20 mg [Study 3 in Clinical Studies (14)], there were no significant differences in the effects on hemodynamic variables between doses. Single oral doses of sildenafil 100 mg administered to healthy volunteers produced decreases in supine blood pressure (mean maximum decrease in systolic/diastolic blood pressure of 8/5 mmHg). The decrease in blood pressure was most notable approximately 1–2 hours after dosing, and was not different from placebo at 8 hours. This metabolite has a phosphodiesterase selectivity profile similar to sildenafil and an in vitro potency for PDE-5 approximately 50% of the parent drug.

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In healthy volunteers, plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil, so that the metabolite accounts for about 20% of sildenafil's pharmacologic effects. In patients with PAH, however, the ratio of the metabolite to sildenafil is higher.

More about Viagra (sildenafil)

REVATIO (sildenafil) Injection: REVATIO is supplied as a clear, colorless, sterile, ready to use solution in a single-use vial containing 10 mg/12.5 mL of sildenafil. Each mL of solution contains 1.124 mg sildenafil citrate (equivalent to 0.8 mg sildenafil), 50.5 mg dextrose and water for injection. REVATIO (sildenafil) for Oral Suspension: REVATIO is supplied as white to off-white powders containing 1.57 g of sildenafil citrate (equivalent to1.12 g sildenafil) in an amber glass bottle intended for reconstitution. Following reconstitution with 90 mL water, the volume of the oral suspension is 112 mL and the oral suspension contains 10 mg/mL sildenafil. In addition to the bottle, a press-in bottle adapter and an oral dosing syringe (with 0.5 mL and 2 mL dose markings) are provided.

Highest Development Phases

Sildenafil, therefore, increases cGMP within pulmonary vascular smooth muscle cells resulting in relaxation. In patients with PAH, this can lead to vasodilation of the pulmonary vascular bed and, to a lesser degree, vasodilatation in the systemic circulation. Studies in vitro have shown that sildenafil is selective for PDE-5. Its effect is more potent on PDE-5 than on other known phosphodiesterases (10-fold for PDE6, greater than 80-fold for PDE1, greater than 700-fold for PDE2, PDE3, PDE4, PDE7, PDE8, PDE9, PDE10, and PDE11). The approximately 4,000-fold selectivity for PDE-5 versus PDE3 is important because PDE3 is involved in control of cardiac contractility. Both sildenafil and the active metabolite have terminal half-lives of about 4 hours.

Drug Class	Interaction Effect	Clinical Significance
Nitrates	Risk of sudden hypotension	Avoid concomitant use
Alpha-blockers	Potentiation of blood pressure lowering	Dose adjustment recommended
CYP3A4 inhibitors	Increased sildenafil levels	Risk of side effects
Antibiotics (e.g., erythromycin)	Altered sildenafil metabolism	Monitor for increased side effects