13. NONCLINICAL TOXICOLOGY

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. 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 and 9.1 mmHg, respectively. An evaluation of visual function at doses up to 200 mg revealed no effects of sildenafil on visual acuity, intraocular pressure, or pupillometry.

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Sildenafil is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25 to 63%). Both sildenafil and the active metabolite have terminal half- lives of about 4 hours. In patients with PAH, the average steady-state concentrations were 20 to 50% higher when compared to those of healthy volunteers. Pediatric use information is approved for Viatris Specialty LLC's, REVATIO ®(sildenafi) tablets. Healthy 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 mild (CLcr = 50-80 mL/min) and moderate (CLcr = 30-49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of sildenafil (50 mg) was not altered. 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. In 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.

Different sildenafil strengths

The improvement in walk distance was apparent after 4 weeks of treatment and was maintained at Week 8 and Week 12.Figure 3. Change from Baseline in 6-Minute Walk Distance (meters) at Weeks 4, 8, and 12 in SUPER-1: Mean (95% Confidence Interval)Figure 4 displays subgroup efficacy analyses in SUPER-1 for the change from baseline in 6- Minute Walk Distance at Week 12 including baseline walk distance, disease etiology, functional class, gender, age, and hemodynamic parameters.Figure 4. Placebo-Corrected Change From Baseline in 6-Minute Walk Distance (meters) at Week 12 by Study Subpopulation in SUPER-1: Mean (95% Confidence Interval)Key:PAH = pulmonary arterial hypertension; CTD = connective tissue disease; PH = pulmonary hypertension; PAP = pulmonary arterial pressure; PVRI = pulmonary vascular resistance index; TID = three times daily.SUPER-2 (NCT00159887) Long-term Treatment of PAHIn a long-term follow-up of patients who were treated with sildenafil (n=277), K-M estimates of survival at 1, 2, and 3 years were 94%, 88%, and 79%, respectively. These uncontrolled observations do not allow comparison with a group not given sildenafil and cannot be used to determine the long term-effect of sildenafil on mortality.PACES-1 (NCT00159861) - Sildenafil Co-administered with EpoprostenolA randomized, double-blind, placebo-controlled study (PACES-1) was conducted in 267 patients with PAH who were taking stable doses of intravenous epoprostenol. Patients had to have a mean pulmonary artery pressure (mPAP) greater than or equal to 25 mmHg and a pulmonary capillary wedge pressure (PCWP) less than or equal to 15 mmHg at rest via right heart catheterization within 21 days before randomization, and a baseline 6-minute walk test distance greater than or equal to 100 meters and less than or equal to 450 meters (mean 349 meters).Patients were randomized to placebo or sildenafil (in a fixed titration starting from 20 mg to 40 mg and then 80 mg, three times a day) and all patients continued intravenous epoprostenol therapy.At baseline patients had PPH (80%) or PAH secondary to CTD (20%); WHO Functional Class I (1%), II (26%), III (67%), or IV (6%); and the mean age was 48 years, 80% were female, and 79% were Caucasian.There was a statistically significant greater increase from baseline in 6-minute walk distance at Week 16 (primary endpoint) for the sildenafil group compared with the placebo group.

Recent Major Changes

The mean change from baseline at Week 16 (last observation carried forward) was 30 meters for the sildenafil group compared with 4 meters for the placebo group giving an adjusted treatment difference of 26 meters (95% CI: 10.8, 41.2) (p = 0.0009).Patients on sildenafil achieved a statistically significant reduction in mPAP compared to those on placebo. A mean placebo-corrected treatment effect of -3.9 mmHg was observed in favor of sildenafil (95% CI: -5.7, -2.1) (p = 0.00003).Time to clinical worsening of PAH was defined as the time from randomization to the first occurrence of a clinical worsening event (death, lung transplantation, initiation of bosentan therapy, or clinical deterioration requiring a change in epoprostenol therapy). Table 4 displays the number of patients with clinical worsening events in PACES-1. Kaplan-Meier estimates and a stratified log-rank test demonstrated that placebo-treated patients were 3 times more likely to experience a clinical worsening event than sildenafil-treated patients and that sildenafil- treated patients experienced a significant delay in time to clinical worsening versus placebo- treated patients (p = 0.0074).

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Patients with severe hepatic impairment (Child- Pugh class C) have not been studied. Sildenafil is a weak inhibitor of the cytochrome P450 sildenafil citrate 100mg tablets isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A (IC50 greater than 150 µM).

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The 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. Effects of Other Drugs on Sildenafil Pharmacokinetics Population 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. Concomitant administration of strong CYP3A inducers is expected to cause substantial decreases in plasma levels of sildenafil. The 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 20 mg is a prescription medication used for erectile dysfunction.
• It helps increase blood flow to the penis during sexual activity.
• Typically prescribed for men with ED to improve sexual performance.

13 NONCLINICAL TOXICOLOGY 13.1 Carcinogenesis, Mutagenesis, Impairment of FertilitySildenafil was not carcinogenic when administered to rats for up to 24 months at 60 mg/kg/day, a dose resulting in total systemic exposure (AUC) to unbound sildenafil and its major metabolite 33- and 37-times, for male and female rats, respectively, the human exposure at the RHD of 20 mg three times a day. Sildenafil was not carcinogenic when administered to male and female mice for up to 21 and 18 months, respectively, at doses up to a maximally tolerated level of 10 mg/kg/day, a dose equivalent to the RHD on a mg/m 2basis.Sildenafil was negative in in vitrobacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitrohuman lymphocytes and in vivomouse micronucleus assays to detect clastogenicity.There was no impairment of fertility in male or female rats given up to 60 mg sildenafil/kg/day, a dose producing a total systemic exposure (AUC) to unbound sildenafil and its major metabolite of 19- and 38-times for males and females, respectively, the human exposure at the RHD of 20 mg three times a day. Sildenafil was not carcinogenic when administered to rats for up to 24 months at 60 mg/kg/day, a dose resulting in total systemic exposure (AUC) to unbound sildenafil and its major metabolite 33- and 37-times, for male and female rats, respectively, the human exposure at the RHD of 20 mg three sildenafil softgel capsule times a day. Sildenafil was not carcinogenic when administered to male and female mice for up to 21 and 18 months, respectively, at doses up to a maximally tolerated level of 10 mg/kg/day, a dose equivalent to the RHD on a mg/m 2basis. There was no impairment of fertility in male or female rats given up to 60 mg sildenafil/kg/day, a dose producing a total systemic exposure (AUC) to unbound sildenafil and its major metabolite of 19- and 38-times for males and females, respectively, the human exposure at the RHD of 20 mg three times a day. 14 CLINICAL STUDIES SUPER-1 (NCT00644605) - Sildenafil monotherapy [20 mg, 40 mg, and 80 mg three times a day]A randomized, double-blind, placebo-controlled study of sildenafil (SUPER-1) was conducted in 277 patients with PAH (defined as a mean pulmonary artery pressure ≥25 mmHg at rest with a pulmonary capillary wedge pressure <15 mmHg). Patients were predominantly WHO Functional Classes II-III. Patients who had failed to respond to bosentan were also excluded. Patients with left ventricular ejection fraction less than 45% or left ventricular shortening fraction less than 0.2 also were not studied.Patients were randomized to receive placebo (n = 70) or sildenafil 20 mg (n = 69), 40 mg (n = 67) or 80 mg (n = 71) three times a day for a period of 12 weeks. The study population consisted of 25% men and 75% women with a mean age of 49 years (range: 18 to 81 years) and baseline 6- minute walk distance between 100 and 450 meters (mean 343).The primary efficacy endpoint was the change from baseline at Week 12 (at least 4 hours after the last dose) in the 6-minute walk distance. Placebo-corrected mean increases in walk distance of 45-50 meters were observed with all doses of sildenafil.

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Effects of Other Drugs on Sildenafil Pharmacokinetics Population 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. Concomitant administration of strong CYP3A inducers is expected to cause substantial decreases in plasma levels of sildenafil. The 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. 13 NONCLINICAL TOXICOLOGY 13.1 Carcinogenesis, Mutagenesis, Impairment of FertilitySildenafil was not carcinogenic when administered to rats for up to 24 months at 60 mg/kg/day, a dose resulting in total systemic exposure (AUC) to unbound sildenafil and its major metabolite 33- and 37-times, for male and female rats, respectively, the human exposure at the RHD of 20 mg three times a day. Sildenafil was not carcinogenic when administered to male and female mice for up to 21 and 18 months, respectively, at doses up to a maximally tolerated level of 10 mg/kg/day, a dose equivalent to the RHD on a mg/m 2basis.Sildenafil was negative in in vitrobacterial and Chinese hamster ovary cell assays to detect mutagenicity, and in vitrohuman lymphocytes and in vivomouse micronucleus assays to detect clastogenicity.There was no impairment of fertility in male or female rats given up to 60 mg sildenafil/kg/day, a dose producing a total systemic exposure (AUC) to unbound sildenafil and its major metabolite of 19- and 38-times for males and females, respectively, the human exposure at the RHD of 20 mg three times a day.

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Sildenafil was not carcinogenic when administered to rats for up to 24 months at 60 mg/kg/day, a dose resulting in total systemic exposure (AUC) to unbound sildenafil and its major metabolite 33- and 37-times, for male and female rats, respectively, the human exposure at the RHD of 20 mg three sildenafil softgel capsule times a day. Sildenafil was not carcinogenic when administered to male and female mice for up to 21 and 18 months, respectively, at doses up to a maximally tolerated level of 10 mg/kg/day, a dose equivalent to the RHD on a mg/m 2basis. There was no impairment of fertility in male or female rats given up to 60 mg sildenafil/kg/day, a dose producing a total systemic exposure (AUC) to unbound sildenafil and its major metabolite of 19- and 38-times for males and females, respectively, the human exposure at the RHD of 20 mg three times a day. 14 CLINICAL STUDIES SUPER-1 (NCT00644605) - Sildenafil monotherapy [20 mg, 40 mg, and 80 mg three times a day]A randomized, double-blind, placebo-controlled study of sildenafil (SUPER-1) was conducted in 277 patients with PAH (defined as a mean pulmonary artery pressure ≥25 mmHg at rest with a pulmonary capillary wedge pressure <15 mmHg). Patients were predominantly WHO Functional Classes II-III.

Sildenafil Tablets or Oral Suspension for PAH

Patients who had failed to respond to bosentan were also excluded. Patients with left ventricular ejection fraction less than 45% or left ventricular shortening fraction less than 0.2 also were not studied.Patients were randomized to receive placebo (n = 70) or sildenafil 20 mg (n = 69), 40 mg (n = 67) or 80 mg (n = 71) three times a day for a period of 12 weeks. The study population consisted of 25% men and 75% women with a mean age of 49 years (range: 18 to 81 years) and baseline 6- minute walk distance between 100 and 450 meters (mean 343).The primary efficacy endpoint was the change from baseline at Week 12 (at least 4 hours after the last dose) in the 6-minute walk distance. Placebo-corrected mean increases in walk distance of 45-50 meters were observed with all doses of sildenafil. These increases were significantly different from placebo, but the sildenafil for women sildenafil dose groups were not different from each other (see Figure 3), indicating no additional clinical benefit from doses higher than 20 mg three times a day. These increases were significantly different from placebo, but the sildenafil for women sildenafil dose groups were not different from each other (see Figure 3), indicating no additional clinical benefit from doses higher than 20 mg three times a day.

What should I know about storage and disposal of this medication?

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. 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 and 9.1 mmHg, respectively. An evaluation of visual function at doses up to 200 mg revealed no effects of sildenafil on visual acuity, intraocular pressure, or pupillometry. Sildenafil is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (25 to 63%).

What’s the difference between sildenafil and Viagra?

Both sildenafil and the active metabolite have terminal half- lives of about 4 hours. In patients with PAH, the average steady-state concentrations were 20 to 50% higher when compared to those of healthy volunteers. Pediatric use information is approved for Viatris Specialty LLC's, REVATIO ®(sildenafi) tablets. Healthy 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 mild (CLcr = 50-80 mL/min) and moderate (CLcr = 30-49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of sildenafil (50 mg) was not altered.

5.6 Adverse Reactions with the Concomitant Use of Ritonavir

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. In 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. Patients with severe hepatic impairment (Child- Pugh class C) have not been studied. Sildenafil is a weak inhibitor of the cytochrome P450 sildenafil citrate 100mg tablets isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A (IC50 greater than 150 µM). The 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. The improvement in walk distance was apparent after 4 weeks of treatment and was maintained at Week 8 and Week 12.Figure 3. Change from Baseline in 6-Minute Walk Distance (meters) at Weeks 4, 8, and 12 in SUPER-1: Mean (95% Confidence Interval)Figure 4 displays subgroup efficacy analyses in SUPER-1 for the change from baseline in 6- Minute Walk Distance at Week 12 including baseline walk distance, disease etiology, functional class, gender, age, and hemodynamic parameters.Figure 4. Placebo-Corrected Change From Baseline in 6-Minute Walk Distance (meters) at Week 12 by Study Subpopulation in SUPER-1: Mean (95% Confidence Interval)Key:PAH = pulmonary arterial hypertension; CTD = connective tissue disease; PH = pulmonary hypertension; PAP = pulmonary arterial pressure; PVRI = pulmonary vascular resistance index; TID = three times daily.SUPER-2 (NCT00159887) Long-term Treatment of PAHIn a long-term follow-up of patients who were treated with sildenafil (n=277), K-M estimates of survival at 1, 2, and 3 years were 94%, 88%, and 79%, respectively.

• Sildenafil 20 mg is contraindicated with nitrate medications due to risk of severe hypotension.
• Patients with heart problems should consult their doctor before use.
• It’s important to disclose all medications to your healthcare provider.

These uncontrolled observations do not allow comparison with a group not given sildenafil and cannot be used to determine the long term-effect of sildenafil on mortality.PACES-1 (NCT00159861) - Sildenafil Co-administered with EpoprostenolA randomized, double-blind, placebo-controlled study (PACES-1) was conducted in 267 patients with PAH who were taking stable doses of intravenous epoprostenol. Patients had to have a mean pulmonary artery pressure (mPAP) greater than or equal to 25 mmHg and a pulmonary capillary wedge pressure (PCWP) less than or equal to 15 mmHg at rest via right heart catheterization within 21 days before randomization, and a baseline 6-minute walk test distance greater than or equal to 100 meters and less than or equal to 450 meters (mean 349 meters).Patients were randomized to placebo or sildenafil (in a fixed titration starting from 20 mg to 40 mg and then 80 mg, three times a day) and all patients continued intravenous epoprostenol therapy.At baseline patients had PPH (80%) or PAH secondary to CTD (20%); WHO Functional Class I (1%), II (26%), III (67%), or IV (6%); and the mean age was 48 years, 80% were female, and 79% were Caucasian.There was a statistically significant greater increase from baseline in 6-minute walk distance at Week 16 (primary endpoint) for the sildenafil group compared with the placebo group. The mean change from baseline at Week 16 (last observation carried forward) was 30 meters for the sildenafil group compared with 4 meters for the placebo group giving an adjusted treatment difference of 26 meters (95% CI: 10.8, 41.2) (p = 0.0009).Patients on sildenafil achieved a statistically significant reduction in mPAP compared to those on placebo. A mean placebo-corrected treatment effect of -3.9 mmHg was observed in favor of sildenafil (95% CI: -5.7, -2.1) (p = 0.00003).Time to clinical worsening of PAH was defined as the time from randomization to the first occurrence of a clinical worsening event (death, lung transplantation, initiation of bosentan therapy, or clinical deterioration requiring a change in epoprostenol therapy).

• Common side effects of sildenafil include headaches, flushing, and nasal congestion.
• Serious side effects are rare but require immediate medical attention.
• Patients should report any adverse reactions to their healthcare provider.

Table 4 displays the number of patients with clinical worsening events in PACES-1. Kaplan-Meier estimates and a stratified log-rank test demonstrated that placebo-treated patients were 3 times more likely to experience a clinical worsening event than sildenafil-treated patients and that sildenafil- treated patients experienced a significant delay in time to clinical worsening versus placebo- treated patients (p = 0.0074).