WARNINGS AND PRECAUTIONS
Sildenafil tablets had no effect on ritonavir pharmacokinetics [ see Dosage and Administration (2.4) and Drug Interactions (7.4)].Although the interaction between other protease inhibitors and sildenafil has not been studied, their concomitant use is expected to increase sildenafil levels.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. Concomitant administration of strong CYP3A4 inducers, such as rifampin, is expected to cause greater decreases in plasma levels of sildenafil.Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of sildenafil.In healthy male volunteers, there was no evidence of a clinically significant effect of azithromycin (500 mg daily for 3 days) on the systemic exposure of sildenafil or its major circulating metabolite.Pharmacokinetic data from patients in clinical trials showed no effect on sildenafil pharmacokinetics of CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N- desmethyl sildenafil, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers.
| Side Effect | Incidence | Severity | Management Suggestions |
|---|---|---|---|
| Headache | Common | Mild to moderate | Take pain relievers |
| Flushing | Common | Mild | Cool compress, hydration |
| Dizziness | Common | Mild | Sit or lie down immediately |
| Nasal Congestion | Less common | Mild | Use decongestants if needed |
| Visual Disturbances | Rare | Mild | Discontinue and consult doctor |
These effects on the metabolite are not expected to be of clinical consequence.Effects of sildenafil tablets on Other DrugsIn 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 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.In a study of healthy male volunteers, sildenafil (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.Sildenafil (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 max of bosentan (125 mg b.i.d.). The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil at recommended doses has no effect in the absence of sexual stimulation. Studies in vitro have shown that sildenafil is selective for PDE5.
other ED treatments
Sildenafil tablets had no effect on ritonavir pharmacokinetics [ see Dosage and Administration (2.4) and Drug Interactions (7.4)].Although the interaction between other protease inhibitors and sildenafil has not been studied, their concomitant use is expected to increase sildenafil levels.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. Concomitant administration of strong CYP3A4 inducers, such as rifampin, is expected to cause greater decreases in plasma levels of sildenafil.Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of sildenafil.In healthy male volunteers, there was no evidence of a clinically significant effect of azithromycin (500 mg daily for 3 days) on the systemic exposure of sildenafil or its major circulating metabolite.Pharmacokinetic data from patients in clinical trials showed no effect on sildenafil pharmacokinetics of CYP2C9 inhibitors (such as tolbutamide, warfarin), CYP2D6 inhibitors (such as selective serotonin reuptake inhibitors, tricyclic antidepressants), thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N- desmethyl sildenafil, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers. These effects on the metabolite are not expected to be of clinical consequence.Effects of sildenafil tablets on Other DrugsIn 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 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.In a study of healthy male volunteers, sildenafil (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates.Sildenafil (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 max of bosentan (125 mg b.i.d.).
What should I know about sildenafil before taking it?
The physiologic mechanism of erection of the penis involves release of nitric oxide (NO) in the corpus cavernosum during sexual stimulation. NO then activates the enzyme guanylate cyclase, which results in increased levels of cyclic guanosine monophosphate (cGMP), producing smooth muscle relaxation in the corpus cavernosum and allowing inflow of blood. Sildenafil at recommended doses has no effect in the absence of sexual stimulation. Studies in vitro have shown that sildenafil is selective for PDE5. This lower selectivity is thought to be the basis for abnormalities related to color vision [ see Clinical Pharmacology (12.2)].
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In addition to human corpus cavernosum smooth muscle, PDE5 is also found in other tissues including platelets, vascular and visceral smooth muscle, and skeletal muscle, brain, heart, liver, kidney, lung, pancreas, prostate, bladder, testis, and seminal vesicle. The inhibition of PDE5 in some of these tissues by sildenafil may be the basis for the enhanced platelet antiaggregatory activity of NO observed in vitro, an inhibition of platelet thrombus formation in vivo and peripheral arterial-venous dilatation in vivo. Effects of sildenafil tablets on Erectile Response: In eight double-blind, placebo-controlled crossover studies of patients with either organic or psychogenic erectile dysfunction, sexual stimulation resulted in improved erections, as assessed by an objective measurement of hardness and duration of erections (RigiScan ®), after sildenafil tablets administration compared with placebo. The time course of effect was examined in one study, showing an effect for up to 4 hours but the response was diminished compared to 2 hours. Effects of sildenafil tabletson Blood Pressure: Single oral doses of sildenafil (100 mg) administered to healthy volunteers produced decreases in sitting blood pressure (mean maximum decrease in systolic/diastolic blood pressure of 8.3/5.3 mmHg). This lower selectivity is thought to be the basis for abnormalities related to color vision [ see Clinical Pharmacology (12.2)]. In addition to human corpus cavernosum smooth muscle, PDE5 is also found in other tissues including platelets, vascular and visceral smooth muscle, and skeletal muscle, brain, heart, liver, kidney, lung, pancreas, prostate, bladder, testis, and seminal vesicle. The inhibition of PDE5 in some of these tissues by sildenafil may be the basis for the enhanced platelet antiaggregatory activity of NO observed in vitro, an inhibition of platelet thrombus formation in vivo and peripheral arterial-venous dilatation in vivo. Effects of sildenafil tablets on Erectile Response: In eight double-blind, placebo-controlled crossover studies of patients with either organic or psychogenic erectile dysfunction, sexual stimulation resulted in improved erections, as assessed by an objective measurement of hardness and duration of erections (RigiScan ®), after sildenafil tablets administration compared with placebo.
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The time course of effect was examined in one study, showing an effect for up to 4 hours but the response was diminished compared to 2 hours.
How to Take Sildenafil Correctly for Erectile Dysfunction
Effects of sildenafil tabletson Blood Pressure: Single oral doses of sildenafil (100 mg) administered to healthy volunteers produced decreases in sitting blood pressure (mean maximum decrease in systolic/diastolic blood pressure of 8.3/5.3 mmHg).
2.5 Dosage Adjustments in Special Populations
For the 19 subjects who received both sildenafil tablets and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 50 mg sildenafil tablets or matching placebo are shown in Figure 3. Blood pressure was measured after administration of sildenafil tablets at the same times as those specified for the first doxazosin study. There were no severe adverse events potentially related to blood pressure and no episodes of syncope reported in this study. In the third study, a single oral dose of sildenafil tablets 100 mg or matching placebo was administered in a 3-period crossover design to 20 generally healthy males with BPH. The mean subject age in this study was 66.4 years.
Is 20 mg of sildenafil effective for ED?
Two were discontinued after study period 1: one failed to meet pre-dose screening qualifications and the other experienced symptomatic hypotension as a moderately severe adverse event 30 minutes after dosing with open-label sildenafil tablets 50 mg. Of the twenty subjects who were ultimately assigned to treatment, a total of 13 subjects successfully completed dose period 1, and seven had successfully completed the previous doxazosin study (using sildenafil tablets 50 mg). For the 20 subjects who received sildenafil tablets 100 mg and matching placebo, the placebo- subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 100 mg sildenafil tablets or matching placebo are shown in Figure 4. Blood pressure was measured after administration of sildenafil tablets at the same times as those specified for the previous doxazosin studies. There were no episodes of syncope reported in this study.
Less common
Effect of sildenafil tablets on Blood Pressure When Co-administered with Anti-hypertensives: When sildenafil tablets 100 mg oral was co-administered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic. Effect of sildenafil tablets on Blood Pressure When Co-administered with Alcohol: Sildenafil tablets(50 mg) did not potentiate the hypotensive effect of alcohol (0.5 g/kg) in healthy volunteers with mean maximum blood alcohol levels of 0.08%. The maximum recommended dose of 100 mg sildenafil was not evaluated in this study [ see Drug Interactions (7.5)]. Larger effects were recorded among patients receiving concomitant nitrates [ see Contraindications (4.1)]. Effects of sildenafil tablets on Blood Pressure When Nitroglycerin is subsequently administered: Based on the pharmacokinetic profile of a single 100 mg oral dose given to healthy normal volunteers, the plasma levels of sildenafil at 24 hours post dose are approximately 2 ng/mL (compared to peak plasma levels of approximately 440 ng/mL). Although plasma levels of sildenafil at 24 hours post dose are much lower than at peak concentration, it is unknown whether nitrates can be safely co-administered at this time point [ see Contraindications (4.1)]. Effects of Sildenafil tablets on Blood Pressure When Co-administered with Alpha-Blockers: Three double-blind, placebo-controlled, randomized, two-way crossover studies were conducted to assess the interaction of sildenafil tablets with doxazosin, an alpha-adrenergic blocking agent. In the first study, a single oral dose of sildenafil tablets100 mg or matching placebo was administered in a 2-period crossover design to 4 generally healthy males with benign prostatic hyperplasia (BPH).
What are Sildenafil Tablets
Larger effects were recorded among patients receiving concomitant nitrates [ see Contraindications (4.1)]. Effects of sildenafil tablets on Blood Pressure When Nitroglycerin is subsequently administered: Based on the pharmacokinetic profile of a single 100 mg oral dose given to healthy normal volunteers, the plasma levels of sildenafil at 24 hours post dose are approximately 2 ng/mL (compared to peak plasma levels of approximately 440 ng/mL). Although plasma levels of sildenafil at 24 hours post dose are much lower than at peak concentration, it is unknown whether nitrates can be safely co-administered at this time point [ see Contraindications (4.1)]. Effects of Sildenafil tablets on Blood Pressure When Co-administered with Alpha-Blockers: Three double-blind, placebo-controlled, randomized, two-way crossover studies were conducted to assess the interaction of sildenafil tablets with doxazosin, an alpha-adrenergic blocking agent. In the first study, a single oral dose of sildenafil tablets100 mg or matching placebo was administered in a 2-period crossover design to 4 generally healthy males with benign prostatic hyperplasia (BPH).
Missed Dose
The mean subject age was 66.5 years. For the 17 subjects who received sildenafil tablets25 mg and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: sildenafil oral jelly 100mg The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 25 mg sildenafil tablets or matching placebo are shown in Figure 2. Blood pressure was measured immediately pre-dose and at 15, 30, 45 minutes, and 1, 1.5, 2, 2.5, 3, 4, 6 and 8 hours after sildenafil tablets or matching placebo. No severe adverse events potentially related to blood pressure effects were reported in this group. Of the four subjects who received sildenafil tablets100 mg in the first part of this study, a severe adverse event related to blood pressure effect was reported in one patient (postural hypotension that began 35 minutes after dosing with sildenafil tablets with symptoms lasting for 8 hours), and mild adverse events potentially related to blood pressure effects were reported in two others (dizziness, headache and fatigue at 1 hour after dosing; and dizziness, lightheadedness and nausea at 4 hours after dosing).
Most Asked Questions
Both of these subjects were protocol violators, one due to a low baseline standing SBP, and the other due to baseline orthostatic hypotension. In the second study, a single oral dose of sildenafil tablets 50 mg or matching placebo was administered in a 2-period crossover design to 20 generally healthy males with BPH. The mean subject age in this study was 63.9 years. Twenty subjects received sildenafil tablets 50 mg, but only 19 subjects received matching placebo. This patient had been taking minoxidil, a potent vasodilator, during the study. The mean subject age was 66.5 years. For the 17 subjects who received sildenafil tablets25 mg and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: sildenafil oral jelly 100mg The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 25 mg sildenafil tablets or matching placebo are shown in Figure 2. Blood pressure was measured immediately pre-dose and at 15, 30, 45 minutes, and 1, 1.5, 2, 2.5, 3, 4, 6 and 8 hours after sildenafil tablets or matching placebo. No severe adverse events potentially related to blood pressure effects were reported in this group. Of the four subjects who received sildenafil tablets100 mg in the first part of this study, a severe adverse event related to blood pressure effect was reported in one patient (postural hypotension that began 35 minutes after dosing with sildenafil tablets with symptoms lasting for 8 hours), and mild adverse events potentially related to blood pressure effects were reported in two others (dizziness, headache and fatigue at 1 hour after dosing; and dizziness, lightheadedness and nausea at 4 hours after dosing). Both of these subjects were protocol violators, one due to a low baseline standing SBP, and the other due to baseline orthostatic hypotension. In the second study, a single oral dose of sildenafil tablets 50 mg or matching placebo was administered in a 2-period crossover design to 20 generally healthy males with BPH. The mean subject age in this study was 63.9 years. Twenty subjects received sildenafil tablets 50 mg, but only 19 subjects received matching placebo. This patient had been taking minoxidil, a potent vasodilator, during the study.
- Sildenafil 25 mg can be part of a broader ED management plan.
- Regular check-ups may be necessary to monitor health status.
- Keep a record of any side effects or unusual symptoms.
- Do not share your medication with others to avoid misuse.
For the 19 subjects who received both sildenafil tablets and matching placebo, the placebo-subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 50 mg sildenafil tablets or matching placebo are shown in Figure 3. Blood pressure was measured after administration of sildenafil tablets at the same times as those specified for the first doxazosin study. There were no severe adverse events potentially related to blood pressure and no episodes of syncope reported in this study. In the third study, a single oral dose of sildenafil tablets 100 mg or matching placebo was administered in a 3-period crossover design to 20 generally healthy males with BPH. The mean subject age in this study was 66.4 years.
What side effects can this medication cause?
Two were discontinued after study period 1: one failed to meet pre-dose screening qualifications and the other experienced symptomatic hypotension as a moderately severe adverse event 30 minutes after dosing with open-label sildenafil tablets 50 mg. Of the twenty subjects who were ultimately assigned to treatment, a total of 13 subjects successfully completed dose period 1, and seven had successfully completed the previous doxazosin study (using sildenafil tablets 50 mg).
- Consult your doctor if you experience vision changes or ringing in ears.
- Sildenafil can interact with nitrates, causing dangerous hypotension.
- Use with caution if you have heart problems or low blood pressure.
- Report any persistent or painful erections lasting over 4 hours.
For the 20 subjects who received sildenafil tablets 100 mg and matching placebo, the placebo- subtracted mean maximum decreases from baseline (95% CI) in systolic blood pressure were as follows: The mean profiles of the change from baseline in standing systolic blood pressure in subjects treated with doxazosin in combination with 100 mg sildenafil tablets or matching placebo are shown in Figure 4. Blood pressure was measured after administration of sildenafil tablets at the same times as those specified for the previous doxazosin studies. There were no episodes of syncope reported in this study. Effect of sildenafil tablets on Blood Pressure When Co-administered with Anti-hypertensives: When sildenafil tablets 100 mg oral was co-administered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic. Effect of sildenafil tablets on Blood Pressure When Co-administered with Alcohol: Sildenafil tablets(50 mg) did not potentiate the hypotensive effect of alcohol (0.5 g/kg) in healthy volunteers with mean maximum blood alcohol levels of 0.08%.
What is Sildenafil for Erectile Dysfunction?
The Low Dose: 25mg
Does sildenafil cause different side effects in females?
The maximum recommended dose of 100 mg sildenafil was not evaluated in this study [ see Drug Interactions (7.5)].