Sildenafil 20mg Tablets

Sildenafil tablets are rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (range 25 to 63%). Absorption and Distribution: Sildenafil tablets are rapidly absorbed. When sildenafil tablets are 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%. Metabolism and Excretion:Sildenafil is cleared predominantly by the CYP3A4 (major route) and CYP2C9 (minor route) hepatic microsomal isoenzymes.

Key Point	Explanation	Advice
Take on an empty stomach	Food, especially high-fat meals, can delay onset	Take 30 min to 1 hour before activity
Avoid excessive alcohol	Can impair effectiveness and cause side effects	Limit intake during treatment
Report adverse effects	Headaches, vision changes, or priapism	Contact healthcare provider immediately
Do not exceed recommended dose	Risk of severe side effects	Follow medical advice
Store safely	Keep out of children’s reach	Proper storage is essential

Pharmacokinetics in Special Populations Geriatrics:Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma AUC values of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy younger volunteers (18 to 45 years). Due to age-differences in plasma protein binding, the corresponding increase in the AUC of free (unbound) sildenafil and its active N-desmethyl metabolite were 45% and 57%, respectively [ see Dosage and Administration (2.5),and Use in Specific Populations (8.5)] Renal Impairment:In volunteers with mild (CLcr=50 to 80 mL/min) and moderate (CLcr=30 to 49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of sildenafil tablets (50 mg) were not altered. In volunteers with severe (CLcr <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 [see Dosage and Administration (2.5),and Use in Specific Populations (8.6)]. In addition, N-desmethyl metabolite AUC and C maxvalues significantly increased by 200% and 79%, respectively in subjects with severe renal impairment compared to subjects with normal renal function. Hepatic Impairment:In volunteers with hepatic impairment (Child-Pugh Class A and B), sildenafil clearance was reduced, resulting in increases in AUC (85%) and C max(47%) compared to age-matched volunteers with no hepatic impairment.

Liver Dose Adjustments

At the end of the long-term study, 88% of patients reported that sildenafil tablets improved their erections. Sildenafil tablets improved these aspects of sexual function: frequency, firmness and maintenance of erections; frequency of orgasm; frequency and level of desire; frequency, satisfaction and enjoyment of intercourse; and overall relationship satisfaction. As in the other titration studies, patients were started on 50 mg and allowed to adjust the dose up to 100 mg or down to 25 mg of sildenafil tablets; all patients, however, were receiving 50 mg or 100 mg at the end of the study. There were highly statistically significant improvements on the two principal IIEF questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) on sildenafil tablets compared to placebo. On a global improvement question, 57% of sildenafil tablets patients reported improved erections versus 10% on placebo.

Sildenafil Tablets or Oral Suspension for PAH

Diary data indicated that on sildenafil tablets, 48% of intercourse attempts were successful versus 12% on placebo. The changes from baseline in scoring on the two end point questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) were highly statistically significantly in favor of sildenafil tablets. On a global improvement question, 83% of patients reported improved erections on sildenafil tablets versus 12% on placebo. The pharmacokinetics of sildenafil in patients with severely impaired hepatic function (Child-Pugh Class C) have not been studied [see Dosage and Administration (2.5),and Use in Specific Populations (8.7)]. Drug Interaction Studies Effects of Other Drugs on Sildenafil Tablets Sildenafil metabolism is principally mediated by CYP3A4 (major route) and CYP2C9 (minor route). In vivo studies: Cimetidine (800 mg), a nonspecific CYP inhibitor, caused a 56% increase in plasma sildenafil concentrations when co-administered with sildenafil tablets (50 mg) to healthy volunteers.

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When a single 100 mg dose of sildenafil tablets were administered with erythromycin, a moderate CYP3A4 inhibitor, at steady state (500 mg bid for 5 days), there was a 160% increase in sildenafil C maxand a 182% increase in sildenafil AUC.

Condition	Risk Factors	Recommendations
Use with Nitrates	Risk of severe hypotension	Avoid concurrent use
Severe Heart Disease	Increased cardiac stress	Consult cardiologist before use
Severe Liver or Kidney Impairment	Altered drug metabolism	Dose adjustment or avoid use
Hypotension	Blood pressure too low	Use caution, monitor blood pressure
Retinitis Pigmentosa	Risk of vision changes	Consult eye specialist

In addition, in a study performed in healthy male volunteers, co-administration of the HIV protease inhibitor saquinavir, also a CYP3A4 inhibitor, at steady state (1200 mg tid) with sildenafil tablets (100 mg single dose) resulted in a 140% increase in sildenafil Cmax and a 210% increase in sildenafil AUC. Population pharmacokinetic data from patients in clinical trials also indicated a reduction in sildenafil clearance when it was co- administered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, or cimetidine) [see Dosage and Administration (2.4)and Drug Interactions ( 7.4)]. In another study in healthy male volunteers, co-administration with the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (500 mg bid) with sildenafil tablets (100 mg single dose) resulted in a 300% (4-fold) increase in sildenafil price ireland sildenafil C maxand a 1000% (11-fold) increase in sildenafil plasma AUC. Sildenafil tablets had no effect on ritonavir pharmacokinetics [see Dosage and Administration (2.4)and Drug Interactions (7.4)]. In a study of healthy male volunteers, co-administration of sildenafil at steady state (80 mg t.i.d.) with endothelin receptor antagonist bosentan (a moderate inducer of CYP3A4, CYP2C9 and possibly of CYP2C19) at steady state (125 mg b.i.d.) resulted in a 63% decrease of sildenafil AUC and a 55% decrease in sildenafil C max.

Storage Requirement	Temperature Range	Light Exposure	Humidity Control	Notes
Room Temperature	20–25°C (68–77°F)	Keep away from direct sunlight	Keep in a dry place	Keep out of reach of children
Avoid Humidity	≤60% RH	Store in original container	Avoid bathroom storage	Protect from moisture
Temperature Fluctuations	Avoid extreme temperatures	-	-	Prevent degradation

Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of sildenafil tablets. Effects of Sildenafil Tablets on Other Drugs In vitro studies: Sildenafil is a weak inhibitor of the CYP isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 μM). Given sildenafil peak plasma concentrations of approximately 1 μM after recommended doses, it is unlikely that sildenafil tablets will alter the clearance of substrates of these isoenzymes. In vivo studies: No significant interactions were shown with tolbutamide (250 mg) or warfarin (40 mg), both of which are metabolized by CYP2C9.

Patient Information

Given sildenafil peak plasma concentrations of approximately 1 μM after recommended doses, it is unlikely that sildenafil tablets will alter the clearance of substrates of these isoenzymes. In vivo studies: No significant interactions were shown with tolbutamide (250 mg) or warfarin (40 mg), both of which are metabolized by CYP2C9. Sildenafil tablets (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg). Sildenafil at steady state, at a dose not approved for the treatment of erectile dysfunction (80 mg t.i.d.) resulted in a 50% increase in AUC and a 42% increase in C maxof bosentan (125 mg b.i.d.). Carcinogenesis Sildenafil was not carcinogenic when administered to rats for 24 months at a dose resulting in total systemic drug exposure (AUCs) for unbound sildenafil and its major metabolite of 20-and 38-times, for male and female rats, respectively, the exposures observed in human males given the Maximum Recommended Human Dose (MRHD) of 100 mg.

7.3 Amlodipine

Sildenafil was not carcinogenic when administered to mice for 18 to 21 months at dosages up to the Maximum Tolerated Dose (MTD) of 10 mg/kg/day, approximately 0.4 times the MRHD on a mg/m2 basis in a 50 kg subject. Impairment of Fertility There was no impairment of fertility in rats given sildenafil up to 60 mg/kg/day for 36 days to females and 102 days to males, a dose producing an AUC value of more than 25 times the human male AUC. In clinical studies, sildenafil tablets was assessed for its effect on the ability of men with erectile dysfunction (ED) to engage in sexual activity and in many cases specifically on the ability to achieve and maintain an erection sufficient for satisfactory sexual activity. Sildenafil tablets were evaluated primarily at doses of 25 mg, 50 mg and 100 mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs (fixed dose, titration, parallel, crossover). Sildenafil tablets were administered to more than 3,000 patients aged 19 to 87 years, with ED of various etiologies (organic, psychogenic, mixed) with a mean duration of 5 years. Sildenafil tablets (50 mg) did not potentiate the increase in bleeding time caused by aspirin (150 mg). Sildenafil at steady state, at a dose not approved for the treatment of erectile dysfunction (80 mg t.i.d.) resulted in a 50% increase in AUC and a 42% increase in C maxof bosentan (125 mg b.i.d.).

• Patient support resources are available for those taking sildenafil.
• Many pharmaceutical manufacturers offer patient assistance programs.
• Non-profit organizations provide information and support for ED and PAH.
• The Pulmonary Hypertension Association offers resources for PAH patients.
• Urology care foundations provide educational materials on ED treatments.
• Online forums and support groups can offer peer support and shared experiences.
• Healthcare providers are the primary source for personalized medical advice.
• Pharmacists are an excellent resource for information on dosing and side effects.
• Mental health professionals can help address psychological aspects of ED.
• Cardiac rehabilitation may be recommended for some PAH patients.
• A multidisciplinary approach often yields the best patient outcomes.

Carcinogenesis Sildenafil was not carcinogenic when administered to rats for 24 months at a dose resulting in total systemic drug exposure (AUCs) for unbound sildenafil and its major metabolite of 20-and 38-times, for male and female rats, respectively, the exposures observed in human males given the Maximum Recommended Human Dose (MRHD) of 100 mg. Sildenafil was not carcinogenic when administered to mice for 18 to 21 months at dosages up to the Maximum Tolerated Dose (MTD) of 10 mg/kg/day, approximately 0.4 times the MRHD on a mg/m2 basis in a 50 kg subject. Impairment of Fertility There was no impairment of fertility in rats given sildenafil up to 60 mg/kg/day for 36 days to females and 102 days to males, a dose producing an AUC value of more than 25 times the human male AUC.

12.3 Pharmacokinetics

Drug Interaction Studies Effects of Other Drugs on Sildenafil Tablets Sildenafil metabolism is principally mediated by CYP3A4 (major route) and CYP2C9 (minor route). In vivo studies: Cimetidine (800 mg), a nonspecific CYP inhibitor, caused a 56% increase in plasma sildenafil concentrations when co-administered with sildenafil tablets (50 mg) to healthy volunteers. When a single 100 mg dose of sildenafil tablets were administered with erythromycin, a moderate CYP3A4 inhibitor, at steady state (500 mg bid for 5 days), there was a 160% increase in sildenafil C maxand a 182% increase in sildenafil AUC. In addition, in a study performed in healthy male volunteers, co-administration of the HIV protease inhibitor saquinavir, also a CYP3A4 inhibitor, at steady state (1200 mg tid) with sildenafil tablets (100 mg single dose) resulted in a 140% increase in sildenafil Cmax and a 210% increase in sildenafil AUC. Population pharmacokinetic data from patients in clinical trials also indicated a reduction in sildenafil clearance when it was co- administered with CYP3A4 inhibitors (such as ketoconazole, erythromycin, or cimetidine) [see Dosage and Administration (2.4)and Drug Interactions ( 7.4)].

Sildenafil vs. tadalafil

In another study in healthy male volunteers, co-administration with the HIV protease inhibitor ritonavir, which is a highly potent P450 inhibitor, at steady state (500 mg bid) with sildenafil tablets (100 mg single dose) resulted in a 300% (4-fold) increase in sildenafil price ireland sildenafil C maxand a 1000% (11-fold) increase in sildenafil plasma AUC. Sildenafil tablets had no effect on ritonavir pharmacokinetics [see Dosage and Administration (2.4)and Drug Interactions (7.4)]. In a study of healthy male volunteers, co-administration of sildenafil at steady state (80 mg t.i.d.) with endothelin receptor antagonist bosentan (a moderate inducer of CYP3A4, CYP2C9 and possibly of CYP2C19) at steady state (125 mg b.i.d.) resulted in a 63% decrease of sildenafil AUC and a 55% decrease in sildenafil C max. Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of sildenafil tablets. Effects of Sildenafil Tablets on Other Drugs In vitro studies: Sildenafil is a weak inhibitor of the CYP isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 >150 μM). In clinical studies, sildenafil tablets was assessed for its effect on the ability of men with erectile dysfunction (ED) to engage in sexual activity and in many cases specifically on the ability to achieve and maintain an erection sufficient for satisfactory sexual activity. Sildenafil tablets were evaluated primarily at doses of 25 mg, 50 mg and 100 mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs (fixed dose, titration, parallel, crossover). Sildenafil tablets were administered to more than 3,000 patients aged 19 to 87 years, with ED of various etiologies (organic, psychogenic, mixed) with a mean duration of 5 years. Sildenafil tablets demonstrated statistically significant improvement compared to placebo in all 21 studies.

• 20mg sildenafil is a low dose used for erectile dysfunction.
• It typically begins working within 30-60 minutes.
• Sildenafil should be taken on an empty stomach for best results.
• Common side effects include headache, flushing, and dizziness.
• Consult a doctor before using 20mg sildenafil to ensure safety.

Efficacy Endpoints in Controlled Clinical Studies The effectiveness of sildenafil tablets were evaluated in most studies using several assessment instruments. The primary measure in the principal studies was a sexual function questionnaire (the International Index of Erectile Function -IIEF) administered during a 4-week treatment-free run-in period, at baseline, at follow-up visits, and at the end of double-blind, placebo-controlled, at-home treatment. Efficacy Results from Controlled Clinical Studies The effect on one of the major end points, maintenance of erections after penetration, is shown in Figure 6, for the pooled results of 5 fixed-dose, dose-response studies of greater than one month duration, showing response according to baseline function. Figure 6 shows that regardless of the baseline levels of function, subsequent function in patients treated with sildenafil tablets sildenafil citrate tables were better than that seen in patients treated with placebo. Effect of Sildenafil Tablets and Placebo on Maintenance of Erection by Baseline Score. Sixty-three percent, 74%, and 82% of the patients on 25 mg, 50 mg and 100 mg of sildenafil tablets, respectively, reported an improvement in their erections, compared to 24% on placebo. Overall treatment p<0.0001 Figure 7. Percentage of Patients Reporting an Improvement in Erections .

What side effects can this medication cause?

Sildenafil tablets are rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (range 25 to 63%). Absorption and Distribution: Sildenafil tablets are rapidly absorbed. When sildenafil tablets are 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%. Metabolism and Excretion:Sildenafil is cleared predominantly by the CYP3A4 (major route) and CYP2C9 (minor route) hepatic microsomal isoenzymes. Pharmacokinetics in Special Populations Geriatrics:Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil, resulting in approximately 84% and 107% higher plasma AUC values of sildenafil and its active N-desmethyl metabolite, respectively, compared to those seen in healthy younger volunteers (18 to 45 years).

Dosage Forms and Strengths

Due to age-differences in plasma protein binding, the corresponding increase in the AUC of free (unbound) sildenafil and its active N-desmethyl metabolite were 45% and 57%, respectively [ see Dosage and Administration (2.5),and Use in Specific Populations (8.5)] Renal Impairment:In volunteers with mild (CLcr=50 to 80 mL/min) and moderate (CLcr=30 to 49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of sildenafil tablets (50 mg) were not altered. In volunteers with severe (CLcr <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 [see Dosage and Administration (2.5),and Use in Specific Populations (8.6)]. In addition, N-desmethyl metabolite AUC and C maxvalues significantly increased by 200% and 79%, respectively in subjects with severe renal impairment compared to subjects with normal renal function. Hepatic Impairment:In volunteers with hepatic impairment (Child-Pugh Class A and B), sildenafil clearance was reduced, resulting in increases in AUC (85%) and C max(47%) compared to age-matched volunteers with no hepatic impairment. The pharmacokinetics of sildenafil in patients with severely impaired hepatic function (Child-Pugh Class C) have not been studied [see Dosage and Administration (2.5),and Use in Specific Populations (8.7)]. In these studies, involving about 1600 patients, analyses of patient diaries showed no effect of sildenafil tablets on rates of attempted intercourse (about 2 per week), but there was clear treatment-related improvement in sexual function: per patient weekly success rates averaged 1.3 on 50 to 100 mg of sildenafil tablets vs 0.4 on placebo; similarly, group mean success rates (total successes divided by total attempts) were about 66% on sildenafil tablets vs about 20% on placebo. At the end of the long-term study, 88% of patients reported that sildenafil tablets improved their erections. Sildenafil tablets improved these aspects of sexual function: frequency, firmness and maintenance of erections; frequency of orgasm; frequency and level of desire; frequency, satisfaction and enjoyment of intercourse; and overall relationship satisfaction.

What happens if I overdose?

Sildenafil tablets demonstrated statistically significant improvement compared to placebo in all 21 studies. Efficacy Endpoints in Controlled Clinical Studies The effectiveness of sildenafil tablets were evaluated in most studies using several assessment instruments. The primary measure in the principal studies was a sexual function questionnaire (the International Index of Erectile Function -IIEF) administered during a 4-week treatment-free run-in period, at baseline, at follow-up visits, and at the end of double-blind, placebo-controlled, at-home treatment. Efficacy Results from Controlled Clinical Studies The effect on one of the major end points, maintenance of erections after penetration, is shown in Figure 6, for the pooled results of 5 fixed-dose, dose-response studies of greater than one month duration, showing response according to baseline function. Figure 6 shows that regardless of the baseline levels of function, subsequent function in patients treated with sildenafil tablets sildenafil citrate tables were better than that seen in patients treated with placebo.

How Sildenafil works

Effect of Sildenafil Tablets and Placebo on Maintenance of Erection by Baseline Score. Sixty-three percent, 74%, and 82% of the patients on 25 mg, 50 mg and 100 mg of sildenafil tablets, respectively, reported an improvement in their erections, compared to 24% on placebo. Overall treatment p<0.0001 Figure 7. Percentage of Patients Reporting an Improvement in Erections . In these studies, involving about 1600 patients, analyses of patient diaries showed no effect of sildenafil tablets on rates of attempted intercourse (about 2 per week), but there was clear treatment-related improvement in sexual function: per patient weekly success rates averaged 1.3 on 50 to 100 mg of sildenafil tablets vs 0.4 on placebo; similarly, group mean success rates (total successes divided by total attempts) were about 66% on sildenafil tablets vs about 20% on placebo. As in the other titration studies, patients were started on 50 mg and allowed to adjust the dose up to 100 mg or down to 25 mg of sildenafil tablets; all patients, however, were receiving 50 mg or 100 mg at the end of the study. There were highly statistically significant improvements on the two principal IIEF questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) on sildenafil tablets compared to placebo. On a global improvement question, 57% of sildenafil tablets patients reported improved erections versus 10% on placebo. Diary data indicated that on sildenafil tablets, 48% of intercourse attempts were successful versus 12% on placebo. The changes from baseline in scoring on the two end point questions (frequency of successful penetration during sexual activity and maintenance of erections after penetration) were highly statistically significantly in favor of sildenafil tablets. On a global improvement question, 83% of patients reported improved erections on sildenafil tablets versus 12% on placebo.