Its effect is more potent on PDE5 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). Sildenafil is only about 10 times as potent for PDE5 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 [seeClinical Pharmacology (12.2)].In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE5 is also found in other tissues including vascular and visceral smooth muscle and in platelets.
The inhibition of PDE5 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.12.2 PharmacodynamicsEffects of Sildenafil Citrate on Hemodynamic MeasuresAdultsPatients on all sildenafil citrate doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [ see SUPER-1 in Clinical Studies (14)] .
Its effect is more potent on PDE5 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). Sildenafil is only about 10 times as potent for PDE5 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 [seeClinical Pharmacology (12.2)].In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE5 is also found in other tissues including vascular and visceral smooth muscle and in platelets. The inhibition of PDE5 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.12.2 PharmacodynamicsEffects of Sildenafil Citrate on Hemodynamic MeasuresAdultsPatients on all sildenafil citrate doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [ see SUPER-1 in Clinical Studies (14)] . Data on other hemodynamic measures for the sildenafil citrate 20 mg three times a day and placebo dosing regimens is displayed in Table 2.
The relationship between these effects and improvements in 6-minute walk distance is unknown.Table 2: Changes from Baseline in Hemodynamic Parameters at Week 12 [mean (95% CI)] for the Sildenafil Citrate 20 mg Three Times a Day and Placebo GroupEffects of Sildenafil Citrate on Blood PressureSingle 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 to 2 hours after dosing and was not different from placebo at 8 hours. 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. Larger effects were recorded among patients receiving concomitant nitrates [seeContraindications (4)].Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (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.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.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).Effects of Sildenafil Citrate on VisionAt 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. Data on other hemodynamic measures for the sildenafil citrate 20 mg three times a day and placebo dosing regimens is displayed in Table 2.
The relationship between these effects and improvements in 6-minute walk distance is unknown.Table 2: Changes from Baseline in Hemodynamic Parameters at Week 12 [mean (95% CI)] for the Sildenafil Citrate 20 mg Three Times a Day and Placebo GroupEffects of Sildenafil Citrate on Blood PressureSingle 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 to 2 hours after dosing and was not different from placebo at 8 hours.
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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. Larger effects were recorded among patients receiving concomitant nitrates [seeContraindications (4)].Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (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.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.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).Effects of Sildenafil Citrate on VisionAt 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.
Sildenafil is not expected to affect the pharmacokinetics of compounds which are substrates of these CYP enzymes at clinically relevant concentrations.In vivo studiesThe effects of other drugs on sildenafil pharmacokinetics and the effects of sildenafil on the exposure to other drugs are shown in Figure 1 and Figure 2, respectively.Figure 1. Effects of Other sildenafil 100 mg tab Drugs on Sildenafil PharmacokineticsFigure 2. Effects of Sildenafil on Other DrugsCYP3A Inhibitors and Beta BlockersPopulation pharmacokinetic analysis of data from patients in clinical trials indicated an approximately 30% reduction in sildenafil clearance when it was co-administered with mild/moderate CYP3A inhibitors and an approximately 34% reductions in sildenafil clearance when co-administered with beta-blockers. This concentration range covers the same increased sildenafil exposure observed in specifically-designed drug interaction studies with CYP3A inhibitors (except for potent inhibitors such as ketoconazole, itraconazole, and ritonavir).CYP3A4 Inducers Including BosentanConcomitant administration of strong CYP3A inducers is expected to cause substantial decreases in plasma levels of sildenafil.Population pharmacokinetic analysis of data from patients in clinical trials indicated approximately 3-fold the sildenafil clearance when it was co-administered with mild CYP3A inducers.EpoprostenolThe mean reduction of sildenafil (80 mg three times a day) bioavailability when co-administered with epoprostenol was 28%, resulting in about 22% lower mean average steady-state concentrations. Sildenafil is an inhibitor of cGMP specific PDE-5 in the smooth muscle of the pulmonary vasculature, where PDE-5 is responsible for degradation of cGMP.
Studies in vitrohave shown that sildenafil is selective for PDE5. This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels [seeClinical Pharmacology (12.2)]. In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE5 is also found in other tissues including vascular and visceral smooth muscle and in platelets. The inhibition of PDE5 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. Effects of Sildenafil Citrate on Hemodynamic Measures Patients on all sildenafil citrate doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [ see SUPER-1 in Clinical Studies (14)] . An evaluation of visual function at doses up to 200 mg revealed no effects of sildenafil citrate on visual acuity, intraocular pressure, or pupillometry.Pediatric use information is approved for Viatris Specialty LLC's, REVATIO (sildenafil) tablets. However, due to Viatris Specialty LLC's marketing exclusivity rights, this drug product is not labeled with that information.12.3 PharmacokineticsAbsorption and DistributionSildenafil citrate is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25% to 63%). When sildenafil citrate is taken with a high-fat meal, the rate of absorption is reduced, with a mean delay in T maxof 60 minutes and a mean reduction in C maxof 29%.
This metabolite has a phosphodiesterase selectivity profile similar to sildenafil and an in vitropotency for PDE-5 approximately 50% of the parent drug. Both sildenafil and the active metabolite have terminal half-lives of about 4 hours.After oral administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of the administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose).Population PharmacokineticsAge, gender, race, and renal and hepatic function were included as factors assessed in the population pharmacokinetic model to evaluate sildenafil pharmacokinetics in patients with PAH. There was also a doubling of C minlevels compared to healthy volunteers.
Both findings suggest a lower clearance and/or a higher oral bioavailability of sildenafil in patients with PAH compared to healthy volunteers.Pediatric PatientsPediatric use information is approved for Viatris Specialty LLC’s, REVATIO (sildenafil) tablets. However, due to Viatris Specialty LLC’s marketing exclusivity rights, this drug product is not labeled with that information.Geriatric PatientsHealthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy younger volunteers (18 to 45 years).
Table 2: Changes from Baseline in Hemodynamic Parameters at Week 12 [mean (95% CI)] for the Sildenafil Citrate 20 mg Three Times a Day and Placebo Group Effects of Sildenafil Citrate on Blood Pressure 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). Larger effects were recorded among patients receiving concomitant nitrates [seeContraindications (4)]. Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (ECG). 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. Pediatric use information is approved for Viatris Specialty LLC's, REVATIO (sildenafil) tablets.
However, due to Viatris Specialty LLC's marketing exclusivity rights, this drug product is not labeled with that information. In volunteers with severe (CLcr less than 30 mL/min) renal impairment, sildenafil clearance was reduced, resulting in approximately doubling of AUC and C maxcompared to age-matched volunteers with no renal impairment.
| Condition | Details |
|---|---|
| Temperature | Store below 25°C (77°F) |
| Humidity | Keep in a dry place, away from moisture |
| Light Exposure | Store in a dark place, protect from light |
| Child Safety | Keep out of reach of children |
In addition, N-desmethyl metabolite AUC and C maxvalues were significantly increased 200% and 79%, respectively, in patients with severe renal impairment compared to patients with normal renal function.Hepatic ImpairmentIn volunteers with mild to moderate hepatic cirrhosis (Child-Pugh class A and B), sildenafil clearance was reduced, resulting in increases in AUC (84%) and C max(47%) compared to age-matched volunteers with no hepatic impairment. Sildenafil is not expected to affect the pharmacokinetics of compounds which are substrates of these CYP enzymes at clinically relevant concentrations.In vivo studiesThe effects of other drugs on sildenafil pharmacokinetics and the effects of sildenafil on the exposure to other drugs are shown in Figure 1 and Figure 2, respectively.Figure 1.
An evaluation of visual function at doses up to 200 mg revealed no effects of sildenafil citrate on visual acuity, intraocular pressure, or pupillometry.Pediatric use information is approved for Viatris Specialty LLC's, REVATIO (sildenafil) tablets. However, due to Viatris Specialty LLC's marketing exclusivity rights, this drug product is not labeled with that information.12.3 PharmacokineticsAbsorption and DistributionSildenafil citrate is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25% to 63%). When sildenafil citrate is taken with a high-fat meal, the rate of absorption is reduced, with a mean delay in T maxof 60 minutes and a mean reduction in C maxof 29%. This metabolite has a phosphodiesterase selectivity profile similar to sildenafil and an in vitropotency for PDE-5 approximately 50% of the parent drug. Both sildenafil and the active metabolite have terminal half-lives of about 4 hours.After oral administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of the administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose).Population PharmacokineticsAge, gender, race, and renal and hepatic function were included as factors assessed in the population pharmacokinetic model to evaluate sildenafil pharmacokinetics in patients with PAH.
There was also a doubling of C minlevels compared to healthy volunteers. Both findings suggest a lower clearance and/or a higher oral bioavailability of sildenafil in patients with PAH compared to healthy volunteers.Pediatric PatientsPediatric use information is approved for Viatris Specialty LLC’s, REVATIO (sildenafil) tablets. However, due to Viatris Specialty LLC’s marketing exclusivity rights, this drug product is not labeled with that information.Geriatric PatientsHealthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma concentrations of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy younger volunteers (18 to 45 years). In volunteers with severe (CLcr less than 30 mL/min) renal impairment, sildenafil clearance was reduced, resulting in approximately doubling of AUC and C maxcompared to age-matched volunteers with no renal impairment. In addition, N-desmethyl metabolite AUC and C maxvalues were significantly increased 200% and 79%, respectively, in patients with severe renal impairment compared to patients with normal renal function.Hepatic ImpairmentIn volunteers with mild to moderate hepatic cirrhosis (Child-Pugh class A and B), sildenafil clearance was reduced, resulting in increases in AUC (84%) and C max(47%) compared to age-matched volunteers with no hepatic impairment. Effects of Other sildenafil 100 mg tab Drugs on Sildenafil PharmacokineticsFigure 2. Effects of Sildenafil on Other DrugsCYP3A Inhibitors and Beta BlockersPopulation pharmacokinetic analysis of data from patients in clinical trials indicated an approximately 30% reduction in sildenafil clearance when it was co-administered with mild/moderate CYP3A inhibitors and an approximately 34% reductions in sildenafil clearance when co-administered with beta-blockers.
This concentration range covers the same increased sildenafil exposure observed in specifically-designed drug interaction studies with CYP3A inhibitors (except for potent inhibitors such as ketoconazole, itraconazole, and ritonavir).CYP3A4 Inducers Including BosentanConcomitant administration of strong CYP3A inducers is expected to cause substantial decreases in plasma levels of sildenafil.Population pharmacokinetic analysis of data from patients in clinical trials indicated approximately 3-fold the sildenafil clearance when it was co-administered with mild CYP3A inducers.EpoprostenolThe mean reduction of sildenafil (80 mg three times a day) bioavailability when co-administered with epoprostenol was 28%, resulting in about 22% lower mean average steady-state concentrations. Sildenafil is an inhibitor of cGMP specific PDE-5 in the smooth muscle of the pulmonary vasculature, where PDE-5 is responsible for degradation of cGMP. Studies in vitrohave shown that sildenafil is selective for PDE5.
This lower selectivity is thought to be the basis for abnormalities related to color vision observed with higher doses or plasma levels [seeClinical Pharmacology (12.2)]. In addition to pulmonary vascular smooth muscle and the corpus cavernosum, PDE5 is also found in other tissues including vascular and visceral smooth muscle and in platelets. The inhibition of PDE5 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. Effects of Sildenafil Citrate on Hemodynamic Measures Patients on all sildenafil citrate doses achieved a statistically significant reduction in mean pulmonary arterial pressure (mPAP) compared to those on placebo in a study with no background vasodilators [ see SUPER-1 in Clinical Studies (14)] . Table 2: Changes from Baseline in Hemodynamic Parameters at Week 12 [mean (95% CI)] for the Sildenafil Citrate 20 mg Three Times a Day and Placebo Group Effects of Sildenafil Citrate on Blood Pressure 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).
| Side Effect | Frequency | Severity | Management Tips |
|---|---|---|---|
| Headache | Common | Mild | Hydration, pain relievers |
| Flushing | Common | Mild | Cool environment, relaxation |
| Nasal Congestion | Less frequent | Mild | Use of decongestants |
| Dizziness | Less frequent | Mild | Sit or lie down immediately |
Larger effects were recorded among patients receiving concomitant nitrates [seeContraindications (4)].
| Parameter | Details |
|---|---|
| Onset of Action | 30-60 minutes |
| Peak Effect | About 1 hour |
| Duration of Effect | 4-6 hours |
| Factors Influencing | Food intake, alcohol, metabolism |
Single oral doses of sildenafil up to 100 mg in healthy volunteers produced no clinically relevant effects on electrocardiogram (ECG). 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. Pediatric use information is approved for Viatris Specialty LLC's, REVATIO (sildenafil) tablets. However, due to Viatris Specialty LLC's marketing exclusivity rights, this drug product is not labeled with that information.