12 CLINICAL PHARMACOLOGY

Decrease in sildenafil tablets dosage is recommended (2.4,5.6) Most common adverse reactions (≥ 2%) include headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness and rash (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Evaric Pharmaceuticals, Inc. at 1-866-495-1995 or FDA at 1-800-FDA-1088 or •Sildenafil tablets can potentiate the hypotensive effects of nitrates, alpha blockers, and anti-hypertensives ( 4.1, 5.5, 7.1, 7.2, 7.3, 12.2) •With concomitant use of alpha blockers, initiate sildenafil tablets at 25 mg dose (2.3) •CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase sildenafil tablets exposure (2.4, 7.4,12.3) •Ritonavir: Do not exceed a maximum single dose of 25 mg in a 48 hour period ( 2.4, 5.6) •Erythromycin or strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, saquinavir): Consider a starting dose of 25 mg (2.4,7.4) Sildenafil tablets are indicated for the treatment of erectile dysfunction. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. Sildenafil tablets were shown to potentiate the hypotensive effects of nitrates and its administration in patients who use nitric oxide donors such as organic nitrates or organic nitrites in any form is therefore contraindicated [see Contraindications (4.1),Drug Interactions (7.1),and Clinical Pharmacology (12.2)].

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Decrease in sildenafil tablets dosage is recommended (2.4,5.6) Most common adverse reactions (≥ 2%) include headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness and rash (6.1) To report SUSPECTED ADVERSE REACTIONS, contact Evaric Pharmaceuticals, Inc. at 1-866-495-1995 or FDA at 1-800-FDA-1088 or •Sildenafil tablets can potentiate the hypotensive effects of nitrates, alpha blockers, and anti-hypertensives ( 4.1, 5.5, 7.1, 7.2, 7.3, 12.2) •With concomitant use of alpha blockers, initiate sildenafil tablets at 25 mg dose (2.3) •CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase sildenafil tablets exposure (2.4, 7.4,12.3) •Ritonavir: Do not exceed a maximum single dose of 25 mg in a 48 hour period ( 2.4, 5.6) •Erythromycin or strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, saquinavir): Consider a starting dose of 25 mg (2.4,7.4) Sildenafil tablets are indicated for the treatment of erectile dysfunction. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. Sildenafil tablets were shown to potentiate the hypotensive effects of nitrates and its administration in patients who use nitric oxide donors such as organic nitrates or organic nitrites in any form is therefore contraindicated [see Contraindications (4.1),Drug Interactions (7.1),and Clinical Pharmacology (12.2)]. When sildenafil tablets are co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating sildenafil tablets treatment and sildenafil tablets should be initiated at 25 mg [see Warnings and Precautions (5.5),Drug Interactions (7.2),and Clinical Pharmacology (12.2)].

FAQs About Sildenafil Dosage

Ritonavir The recommended dose for ritonavir-treated patients is 25 mg prior to sexual activity and the recommended maximum dose is 25 mg within a 48 hour period because concomitant administration increased the blood levels of sildenafil by 11-fold [see Warnings and Precautions (5.6),Drug Interactions (7.4),and Clinical Pharmacology (12.3)]. CYP3A4 Inhibitors Consider a starting dose of 25 mg in patients treated with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, or saquinavir) or erythromycin. Clinical data have shown that co-administration with saquinavir or erythromycin increased plasma levels of sildenafil by about 3 fold [see Drug Interactions (7.4)and Clinical Pharmacology (12.3)]. Consider a starting dose of 25 mg in patients > 65 years, patients with hepatic impairment (e.g., cirrhosis), and patients with severe renal impairment (creatinine clearance <30 mL/minute) because administration of sildenafil tablets in these patients resulted in higher plasma levels of sildenafil [see Use in Specific Populations ( 8.5, 8.6, 8.7)and Clinical Pharmacology ( 12.3)]. Sildenafil Tablets USP, 25 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '113' on the other side.

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Sildenafil Tablets USP, 50 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '114' on the other side. Sildenafil Tablets USP, 100 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '115' on the other side. Consistent with its known effects on the nitric oxide/cGMP pathway [see Clinical Pharmacology ( 12.1, 12.2)] ,sildenafil tablets were shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently is therefore contraindicated. After patients have taken sildenafil tablets, it is unknown when nitrates, if necessary, can be safely administered. 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 Dosage and Administration (2.3),Drug Interactions (7.1),and Clinical Pharmacology (12.2)]. When sildenafil tablets are co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating sildenafil tablets treatment and sildenafil tablets should be initiated at 25 mg [see Warnings and Precautions (5.5),Drug Interactions (7.2),and Clinical Pharmacology (12.2)]. Ritonavir The recommended dose for ritonavir-treated patients is 25 mg prior to sexual activity and the recommended maximum dose is 25 mg within a 48 hour period because concomitant administration increased the blood levels of sildenafil by 11-fold [see Warnings and Precautions (5.6),Drug Interactions (7.4),and Clinical Pharmacology (12.3)].

CYP3A4 Inhibitors Consider a starting dose of 25 mg in patients treated with strong CYP3A4 inhibitors (e.g., ketoconazole, itraconazole, or saquinavir) or erythromycin. Clinical data have shown that co-administration with saquinavir or erythromycin increased plasma levels of sildenafil by about 3 fold [see Drug Interactions (7.4)and Clinical Pharmacology (12.3)].

Consider a starting dose of 25 mg in patients > 65 years, patients with hepatic impairment (e.g., cirrhosis), and patients with severe renal impairment (creatinine clearance <30 mL/minute) because administration of sildenafil tablets in these patients resulted in higher plasma levels of sildenafil [see Use in Specific Populations ( 8.5, 8.6, 8.7)and Clinical Pharmacology ( 12.3)].

7.1 Nitrates

Sildenafil Tablets USP, 25 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '113' on the other side.

• Sildenafil 200 mg's safety profile depends on individual health conditions.
• It is important to inform your doctor of all medications being taken.
• Use sildenafil only when needed for sexual activity.
• Avoid engaging in activities that require alertness until effects are known.
• The drug is often part of a broader erectile dysfunction treatment strategy.
• Safe storage is essential to prevent accidental ingestion by children or others.

Sildenafil Tablets USP, 50 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '114' on the other side. Sildenafil Tablets USP, 100 mg are white colored, round-shaped, biconvex, film coated tablets debossed with 'E' on one side and '115' on the other side.

• The optimal time to take sildenafil 200 mg is about 30-60 minutes before sex.
• Do not take sildenafil if you have had a recent stroke or heart attack.
• Sildenafil may cause rare side effects like kidney problems or hearing loss.
• Consult your healthcare provider if pregnant women or breastfeeding.
• Limit caffeine and other stimulants while using sildenafil.
• Proper dosage and medical supervision are key to successful treatment.

Consistent with its known effects on the nitric oxide/cGMP pathway [see Clinical Pharmacology ( 12.1, 12.2)] ,sildenafil tablets were shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using nitric oxide donors such as organic nitrates or organic nitrites in any form either regularly and/or intermittently is therefore contraindicated. After patients have taken sildenafil tablets, it is unknown when nitrates, if necessary, can be safely administered. 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 Dosage and Administration (2.3),Drug Interactions (7.1),and Clinical Pharmacology (12.2)]. Hypersensitivity reactions have been reported, including rash and urticaria [see Adverse Reactions (6.1)]. Therefore, treatments for erectile dysfunction, including sildenafil tablets, should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status. Sildenafil tablets have systemic vasodilatory properties that resulted in transient decreases in supine blood pressure in healthy volunteers (mean maximum decrease of 8.4/5.5 mmHg), [see Clinical Pharmacology (12.2)].While this normally would be expected to be of little consequence in most patients, prior to prescribing sildenafil tablets, physicians should carefully consider whether their patients with underlying cardiovascular disease could be affected adversely by such vasodilatory effects, especially in combination with sexual activity.

• Sildenafil 200 mg is not recommended for women or children.
• Overuse can lead to serious cardiovascular problems.
• The medication should be part of a comprehensive treatment plan.
• Use caution if combining sildenafil with other ED medications.
• Inform your healthcare provider of all health conditions before use.
• Ensure correct timing to maximize the drug's effectiveness.

Use with caution in patients with the following underlying conditions which can be particularly sensitive to the actions of vasodilators including sildenafil tablets – those with left ventricular outflow obstruction (e.g., aortic stenosis, idiopathic hypertrophic subaortic stenosis) and those with severely impaired autonomic control of blood pressure. There are no controlled clinical data on the safety or efficacy of sildenafil tablets in the following groups; if prescribed, this should be done with caution. •Patients who have suffered a myocardial infarction, stroke, or life-threatening arrhythmia within the last 6 months; •Patients with resting hypotension (BP <90/50 mmHg) or hypertension (BP >170/110 mmHg); •Patients with cardiac failure or coronary artery disease causing unstable angina. Sildenafil tablets should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernosal fibrosis or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anemia, multiple myeloma, or leukemia). However, there are no controlled clinical data on the safety or efficacy of sildenafil tablets in patients with sickle oral sildenafil cell or related anemias. Physicians should advise patients to stop use of all phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil tablets, and seek medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a signof non-arteritic anterior ischemic optic neuropathy (NAION), a rare condition and a cause of decreased vision including permanent loss of vision, that has been reported rarely post-marketing in temporal associationwith theuse of all PDE5 inhibitors. Based on published literature, the annual incidence of NAION is 2.5 to 11.8 cases per 100,000 in males aged ≥ 50.An observationalcase-crossover study evaluated the risk of NAION when PDE5 inhibitor use, as a class, occurred immediately before NAION onset (within 5 half-lives), compared to PDE5 inhibitor use in a prior time period.

5.6 Adverse Reactions with the Concomitant Use of Ritonavir

Individuals with ''crowded'' optic disc are also considered at greater risk for NAION compared to the general population, however, evidence is insufficient to support screening of prospective users of PDE5 inhibitors, including sildenafil tablets, for this uncommon condition. There are no controlled clinical data on the safety or efficacy of sildenafil tablets in patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases); if prescribed, this should be done with caution. Physicians should advise patients to stop taking PDE5 inhibitors, including sildenafil tablets, and seek prompt medical attention in the event of sudden decrease or loss of hearing. These events, which may be accompanied by tinnitus and dizziness, have been reported in temporal association to the intake of PDE5 inhibitors, including sildenafil tablets. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors [see Adverse Reactions (6.1, 6.2)].

Inadequate Dosage and Incorrect Usage

Alpha-blockers Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including sildenafil tablets, and alpha-adrenergic blocking agents are both vasodilators with blood pressure lowering effects. In some patients, concomitant use of these two drug classes can lower blood pressure significantly [see Drug Interactions (7.2)and Clinical Pharmacology (12.2)]leading to symptomatic hypotension (e.g., dizziness, lightheadedness, fainting). Consideration should be given to the following: •Patients who demonstrate hemodynamic instability on alpha-blocker therapy alone are at increased risk of symptomatic hypotension with concomitant use of PDE5 inhibitors. In those patients who are stable on alpha-blocker therapy, PDE5 inhibitors should be initiated at the lowest dose [see Dosage and Administration (2.3)].

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•In those patients already taking an optimized dose of a PDE5 inhibitor, alpha-blocker therapy should be initiated at the lowest dose. •Safety of combined use of PDE5 inhibitors and alpha-blockers may be affected by other variables, including intravascular volume depletion and other anti-hypertensive drugs. Anti-hypertensives Sildenafil tablets have systemic vasodilatory properties and may further lower blood pressure in patients taking anti-hypertensive medications. Theresults suggestan approximate 2-fold increase in the risk of NAION, with a risk estimate of 2.15 (95% CI 1.06, 4.34).

• Sildenafil 200 mg can be used by men aged 18 and above.
• It is important to report any history of heart problems before use.
• Alcohol consumption may diminish the effectiveness of sildenafil.
• Sildenafil 200 mg provides longer-lasting erections compared to lower doses.
• Abstain from driving or operating machinery if experiencing dizziness.
• Using sildenafil without medical advice increases health risks.

Other risk factors for NAION,such as the presence of ''crowded'' optic disc, may have contributed to the occurrence of NAION in these studies. Neither the rare post-marketing reports, nor the association of PDE5 inhibitor use and NAION in theobservationalstudies, substantiate a causal relationship between PDE5 inhibitor use and NAION [see Adverse Reactions(6.2)].

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Hypersensitivity reactions have been reported, including rash and urticaria [see Adverse Reactions (6.1)]. Therefore, treatments for erectile dysfunction, including sildenafil tablets, should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status. Sildenafil tablets have systemic vasodilatory properties that resulted in transient decreases in supine blood pressure in healthy volunteers (mean maximum decrease of 8.4/5.5 mmHg), [see Clinical Pharmacology (12.2)].While this normally would be expected to be of little consequence in most patients, prior to prescribing sildenafil tablets, physicians should carefully consider whether their patients with underlying cardiovascular disease could be affected adversely by such vasodilatory effects, especially in combination with sexual activity. Use with caution in patients with the following underlying conditions which can be particularly sensitive to the actions of vasodilators including sildenafil tablets – those with left ventricular outflow obstruction (e.g., aortic stenosis, idiopathic hypertrophic subaortic stenosis) and those with severely impaired autonomic control of blood pressure. There are no controlled clinical data on the safety or efficacy of sildenafil tablets in the following groups; if prescribed, this should be done with caution.

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•Patients who have suffered a myocardial infarction, stroke, or life-threatening arrhythmia within the last 6 months; •Patients with resting hypotension (BP <90/50 mmHg) or hypertension (BP >170/110 mmHg); •Patients with cardiac failure or coronary artery disease causing unstable angina. Sildenafil tablets should be used with caution in patients with anatomical deformation of the penis (such as angulation, cavernosal fibrosis or Peyronie's disease), or in patients who have conditions which may predispose them to priapism (such as sickle cell anemia, multiple myeloma, or leukemia). However, there are no controlled clinical data on the safety or efficacy of sildenafil tablets in patients with sickle oral sildenafil cell or related anemias. Physicians should advise patients to stop use of all phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil tablets, and seek medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a signof non-arteritic anterior ischemic optic neuropathy (NAION), a rare condition and a cause of decreased vision including permanent loss of vision, that has been reported rarely post-marketing in temporal associationwith theuse of all PDE5 inhibitors.

Missed Dose

Based on published literature, the annual incidence of NAION is 2.5 to 11.8 cases per 100,000 in males aged ≥ 50.An observationalcase-crossover study evaluated the risk of NAION when PDE5 inhibitor use, as a class, occurred immediately before NAION onset (within 5 half-lives), compared to PDE5 inhibitor use in a prior time period. Theresults suggestan approximate 2-fold increase in the risk of NAION, with a risk estimate of 2.15 (95% CI 1.06, 4.34). Other risk factors for NAION,such as the presence of ''crowded'' optic disc, may have contributed to the occurrence of NAION in these studies. Neither the rare post-marketing reports, nor the association of PDE5 inhibitor use and NAION in theobservationalstudies, substantiate a causal relationship between PDE5 inhibitor use and NAION [see Adverse Reactions(6.2)]. Therefore, PDE5 inhibitors, including sildenafil tablets, should be used with caution in these patients and only when the anticipated benefits outweigh the risks. Therefore, PDE5 inhibitors, including sildenafil tablets, should be used with caution in these patients and only when the anticipated benefits outweigh the risks. Individuals with ''crowded'' optic disc are also considered at greater risk for NAION compared to the general population, however, evidence is insufficient to support screening of prospective users of PDE5 inhibitors, including sildenafil tablets, for this uncommon condition. There are no controlled clinical data on the safety or efficacy of sildenafil tablets in patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases); if prescribed, this should be done with caution. Physicians should advise patients to stop taking PDE5 inhibitors, including sildenafil tablets, and seek prompt medical attention in the event of sudden decrease or loss of hearing. These events, which may be accompanied by tinnitus and dizziness, have been reported in temporal association to the intake of PDE5 inhibitors, including sildenafil tablets. It is not possible to determine whether these events are related directly to the use of PDE5 inhibitors or to other factors [see Adverse Reactions (6.1, 6.2)].

Alpha-blockers Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including sildenafil tablets, and alpha-adrenergic blocking agents are both vasodilators with blood pressure lowering effects. In some patients, concomitant use of these two drug classes can lower blood pressure significantly [see Drug Interactions (7.2)and Clinical Pharmacology (12.2)]leading to symptomatic hypotension (e.g., dizziness, lightheadedness, fainting). Consideration should be given to the following: •Patients who demonstrate hemodynamic instability on alpha-blocker therapy alone are at increased risk of symptomatic hypotension with concomitant use of PDE5 inhibitors. In those patients who are stable on alpha-blocker therapy, PDE5 inhibitors should be initiated at the lowest dose [see Dosage and Administration (2.3)]. •In those patients already taking an optimized dose of a PDE5 inhibitor, alpha-blocker therapy should be initiated at the lowest dose. •Safety of combined use of PDE5 inhibitors and alpha-blockers may be affected by other variables, including intravascular volume depletion and other anti-hypertensive drugs. Anti-hypertensives Sildenafil tablets have systemic vasodilatory properties and may further lower blood pressure in patients taking anti-hypertensive medications.

Frequently Asked Questions