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For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, sildenafil tablets may be taken anywhere from 30 minutes to 4 hours before sexual activity ( 2.1 ) Based on effectiveness and toleration, may increase to a maximum of 100 mg or decrease to 25 mg ( 2.1 ) Maximum recommended dosing frequency is once per day ( 2.1 ) 2.1 Dosage Information For most patients, the recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. However, sildenafil tablets may be taken anywhere from 30 minutes to 4 hours before sexual activity. The maximum recommended dosing frequency is once per day. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg. 2.2 Use with Food Sildenafil tablets may be taken with or without food. 2.3 Dosage Adjustments in Specific Situations Sildenafil tablets was 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) ]. 2.4 Dosage Adjustments Due to Drug Interactions 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) ]. 2.5 Dosage Adjustments in Special Populations 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) ].

Administration of sildenafil tablets to patients using nitric oxide donors, such as organic nitrates or organic nitrites in any form. Sildenafil tablets was shown to potentiate the hypotensive effect of nitrates ( 4.1 , 7.1 , 12.2 ) Known hypersensitivity to sildenafil or any component of tablet ( 4.2 ) Administration with guanylate cyclase (GC) stimulators, such as riociguat ( 4.3 ) 4.1 Nitrates Consistent with its known effects on the nitric oxide/cGMP pathway [ see Clinical Pharmacology (12.1 , 12.2 ) ], sildenafil tablets was 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) ]. 4.2 Hypersensitivity Reactions Sildenafil tablets are contraindicated in patients with a known hypersensitivity to sildenafil, as contained in sildenafil tablets and REVATIO, or any component of the tablet. Hypersensitivity reactions have been reported, including rash and urticaria [ see Adverse Reactions (6.1) ]. 4.3 Concomitant Guanylate Cyclase (GC) Stimulators Do not use sildenafil tablets in patients who are using a GC stimulator, such as riociguat. PDE5 inhibitors, including sildenafil, may potentiate the hypotensive effects of GC stimulators.

Patients should not use sildenafil if sexual activity is inadvisable due to cardiovascular status ( 5.1 ) Patients should seek emergency treatment if an erection lasts >4 hours. Use sildenafil with caution in patients predisposed to priapism ( 5.2 ) Patients should stop sildenafil tablets and seek medical care if a sudden loss of vision occurs in one or both eyes, which could be a sign of non arteritic anterior ischemic optic neuropathy (NAION). Sildenafil tablets should be used with caution, and only when the anticipated benefits outweigh the risks, in patients with a history of NAION. Patients with a "crowded" optic disc may also be at an increased risk of NAION. ( 5.3 ) Patients should stop sildenafil tablets and seek prompt medical attention in the event of sudden decrease or loss of hearing ( 5.4 ) Caution is advised when sildenafil is co-administered with alpha-blockers or anti-hypertensives. Concomitant use may lead to hypotension ( 5.5 ) Decreased blood pressure, syncope, and prolonged erection may occur at higher sildenafil exposures. In patients taking strong CYP inhibitors, such as ritonavir, sildenafil exposure is increased. Decrease in sildenafil dosage is recommended ( 2.4 , 5.6 ) 5.1 Cardiovascular There is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease. Therefore, treatments for erectile dysfunction, including sildenafil, should not be generally used in men for whom sexual activity is inadvisable because of their underlying cardiovascular status. The evaluation of erectile dysfunction should include a determination of potential underlying causes and the identification of appropriate treatment following a complete medical assessment. Sildenafil has 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, 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 - 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 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. 5.2 Prolonged Erection and Priapism Prolonged erection greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently since market approval of sildenafil tablets. In the event of an erection that persists longer than 4 hours, the patient should seek immediate medical assistance. If priapism is not treated immediately, penile tissue damage and permanent loss of potency could result. Sildenafil 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 in patients with sickle cell or related anemias. 5.3 Effects on the Eye Physicians should advise patients to stop use of all phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil , and seek medical attention in the event of a sudden loss of vision in one or both eyes. Such an event may be a sign of 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 association with the use of all PDE5 inhibitors. Based on published literature, the annual incidence of NAION is 2.5-11.8 cases per 100,000 in males aged ≥ 50. An observational case-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. The results suggest an approximate 2-fold increase in the risk of NAION, with a risk estimate of 2.15 (95% CI 1.06, 4.34). A similar study reported a consistent result, with a risk estimate of 2.27 (95% CI 0.99, 5.20). 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 the observational studies, substantiate a causal relationship between PDE5 inhibitor use and NAION [ see Adverse Reactions (6.2) ]. Physicians should consider whether their patients with underlying NAION risk factors could be adversely affected by use of PDE5 inhibitors. Individuals who have already experienced NAION are at increased risk of NAION recurrence. Therefore, PDE5 inhibitors, including sildenafil , 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, for this uncommon condition. There are no controlled clinical data on the safety or efficacy of sildenafil in patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases); if prescribed, this should be done with caution. 5.4 Hearing Loss Physicians should advise patients to stop taking PDE5 inhibitors, including sildenafil , 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 . 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) ]. 5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives Alpha-blockers Caution is advised when PDE5 inhibitors are co-administered with alpha-blockers. PDE5 inhibitors, including sildenafil, and alpha-adrenergic blocking agents are both vasodilators with blood pressure lowering effects. When vasodilators are used in combination, an additive effect on blood pressure may occur. 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. Patients should be stable on alpha-blocker therapy prior to initiating a PDE5 inhibitor. 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. Stepwise increase in alpha-blocker dose may be associated with further lowering of blood pressure when taking a PDE5 inhibitor. 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 has systemic vasodilatory properties and may further lower blood pressure in patients taking anti-­hypertensive medications. In a separate drug interaction study, when amlodipine, 5 mg or 10 mg, and sildenafil, 100 mg were orally administered concomitantly to hypertensive patients mean additional blood pressure reduction of 8 mmHg systolic and 7 mmHg diastolic were noted [ see Drug Interactions (7.3) and Clinical Pharmacology (12.2) ]. 5.6 Adverse Reactions with the Concomitant Use of Ritonavir The concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC). If sildenafil is prescribed to patients taking ritonavir, caution should be used. Data from subjects exposed to high systemic levels of sildenafil are limited. Decreased blood pressure, syncope, and prolonged erection were reported in some healthy volunteers exposed to high doses of sildenafil (200-800 mg). To decrease the chance of adverse reactions in patients taking ritonavir, a decrease in sildenafil dosage is recommended [ see Dosage and Administration (2.4) , Drug Interactions (7.4) , and Clinical Pharmacology (12.3) ]. 5.7 Combination with other PDE5 Inhibitors or Other Erectile Dysfunction Therapies The safety and efficacy of combinations of sildenafil with other PDE5 Inhibitors, including REVATIO or other pulmonary arterial hypertension (PAH) treatments containing sildenafil, or other treatments for erectile dysfunction have not been studied. Such combinations may further lower blood pressure. Therefore, the use of such combinations is not recommended. 5.8 Effects on Bleeding There have been postmarketing reports of bleeding events in patients who have taken sildenafil . A causal relationship between sildenafil and these events has not been established. In humans, sildenafil has no effect on bleeding time when taken alone or with aspirin. However, in vitro studies with human platelets indicate that sildenafil potentiates the antiaggregatory effect of sodium nitroprusside (a nitric oxide donor). In addition, the combination of heparin and sildenafil had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans. The safety of sildenafil is unknown in patients with bleeding disorders and patients with active peptic ulceration. 5.9 Counseling Patients About Sexually Transmitted Diseases The use of sildenafil offers no protection against sexually transmitted diseases. Counseling of patients about the protective measures necessary to guard against sexually transmitted diseases, including the Human Immunodeficiency Virus (HIV), may be considered.

Sildenafil 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 at 25 mg dose ( 2.3 ) CYP3A4 inhibitors (e.g., ritonavir, ketoconazole, itraconazole, erythromycin): Increase sildenafil 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 ) 7.1 Nitrates Administration of sildenafil with nitric oxide donors such as organic nitrates or organic nitrites in any form is contraindicated. Consistent with its known effects on the nitric oxide/cGMP pathway, sildenafil was shown to potentiate the hypotensive effects of nitrates [ see Dosage and Administration (2.3) , Contraindications (4.1) , Clinical Pharmacology (12.2) ]. 7.2 Alpha-blockers Use caution when co-administering alpha-blockers with sildenafil because of potential additive blood pressure-lowering effects. When sildenafil is co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating sildenafil treatment and sildenafil should be initiated at the lowest dose [ see Dosage and Administration (2.3) , Warnings and Precautions (5.5) , Clinical Pharmacology (12.2) ]. 7.3 Amlodipine When sildenafil 100 mg was co-administered with amlodipine (5 mg or 10 mg) to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic [ see Warnings and Precautions (5.5) , Clinical Pharmacology (12.2) ]. 7.4 Ritonavir and other CYP3A4 inhibitors Co-administration of ritonavir, a strong CYP3A4 inhibitor, greatly increased the systemic exposure of sildenafil (11-fold increase in AUC). It is therefore recommended not to exceed a maximum single dose of 25 mg of sildenafil in a 48 hour period [ see Dosage and Administration (2.4) , Warnings and Precautions (5.6) , Clinical Pharmacology (12.3) ]. Co-administration of erythromycin, a moderate CYP3A4 inhibitor, resulted in a 160% and 182% increases in sildenafil C max and AUC, respectively. Co-administration of saquinavir, a strong CYP3A4 inhibitor, resulted in 140% and 210% increases in sildenafil C max and AUC, respectively. Stronger CYP3A4 inhibitors such as ketoconazole or itraconazole could be expected to have greater effects than seen with saquinavir. A starting dose of 25 mg of sildenafil should be considered in patients taking erythromycin or strong CYP3A4 inhibitors (such as saquinavir, ketoconazole, itraconazole) [ see Dosage and Administration (2.4) , Clinical Pharmacology (12.3) ]. 7.5 Alcohol In a drug-drug interaction study sildenafil 50 mg given with alcohol 0.5 g/kg in which mean maximum blood alcohol levels of 0.08% was achieved, sildenafil did not potentiate the hypotensive effect of alcohol in healthy volunteers [ see Clinical Pharmacology (12.2) ].

The following are discussed in more detail in other sections of the labeling: Cardiovascular [ see Warnings and Precautions (5.1) ] Prolonged Erection and Priapism [ see Warnings and Precautions (5.2) ] Effects on the Eye [ see Warnings and Precautions (5.3) ] Hearing Loss [ see Warnings and Precautions (5.4) ] Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives [ see Warnings and Precautions (5.5) ] Adverse Reactions with the Concomitant Use of Ritonavir [ see Warnings and Precautions (5.6) ] Combination with other PDE5 Inhibitors or Other Erectile Dysfunction Therapies [ see Warnings and Precautions (5.7) ] Effects on Bleeding [ see Warnings and Precautions (5.8) ] Counseling Patients About Sexually Transmitted Diseases [ see Warnings and Precautions (5.9) ] The most common adverse reactions reported in clinical trials (≥ 2%) are headache, flushing, dyspepsia, abnormal vision, nasal congestion, back pain, myalgia, nausea, dizziness, and rash. 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 Nivagen Pharmaceuticals, Inc. at 1-877-977-0687 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch . 6.1 Clinical Trials Experience Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in clinical practice. Sildenafil was administered to over 3700 patients (aged 19-87 years) during pre-marketing clinical trials worldwide. Over 550 patients were treated for longer than one year. In placebo-controlled clinical studies, the discontinuation rate due to adverse reactions for sildenafil (2.5%) was not significantly different from placebo (2.3%). In fixed-dose studies, the incidence of some adverse reactions increased with dose. The type of adverse reactions in flexible-dose studies, which reflect the recommended dosage regimen, was similar to that for fixed- dose studies. At doses above the recommended dose range, adverse reactions were similar to those detailed in Table 1 below but generally were reported more frequently. Table 1: Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Fixed-Dose Phase II/III Studies Adverse Reaction 25 mg (n=312) 50 mg (n=511) 100 mg (n=506) Placebo (n=607) Headache 16% 21% 28% 7% Flushing 10% 19% 18% 2% Dyspepsia 3% 9% 17% 2% Abnormal vision† 1% 2% 11% 1% Nasal congestion 4% 4% 9% 2% Back pain 3% 4% 4% 2% Myalgia 2% 2% 4% 1% Nausea 2% 3% 3% 1% Dizziness 3% 4% 3% 2% Rash 1% 2% 3% 1% † Abnormal Vision: Mild to moderate in severity and transient, predominantly color tinge to vision, but also increased sensitivity to light, or blurred vision. When sildenafil was taken as recommended (on an as-needed basis) in flexible-dose, placebo-controlled clinical trials of two to twenty-six weeks duration, patients took sildenafil at least once weekly, and the following adverse reactions were reported: Table 2. Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Flexible-Dose Phase II/III Studies Adverse Reaction SILDENAFIL CITRATE PLACEBO N=734 N=725 Headache 16% 4% Flushing 10% 1% Dyspepsia 7% 2% Nasal Congestion 4% 2% Abnormal Vision † 3% 0% Back pain 2% 2% Dizziness 2% 1% Rash 2% 1% † Abnormal Vision: Mild and transient, predominantly color tinge to vision, but also increased sensitivity to light or blurred vision. In these studies, only one patient discontinued due to abnormal vision. The following events occurred in <2% of patients in controlled clinical trials; a causal relationship to sildenafil is uncertain. Reported events include those with a plausible relation to drug use; omitted are minor events and reports too imprecise to be meaningful: Body as a Whole: face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury. Cardiovascular: angina pectoris, AV block, migraine, syncope, tachycardia, palpitation, hypotension, postural hypotension, myocardial ischemia, cerebral thrombosis, cardiac arrest, heart failure, abnormal electrocardiogram, cardiomyopathy. Digestive: vomiting, glossitis, colitis, dysphagia, gastritis, gastroenteritis, esophagitis, stomatitis, dry mouth, liver function tests abnormal, rectal hemorrhage, gingivitis. Hemic and Lymphatic: anemia and leukopenia. Metabolic and Nutritional: thirst, edema, gout, unstable diabetes, hyperglycemia, peripheral edema, hyperuricemia, hypoglycemic reaction, hypernatremia. Musculoskeletal: arthritis, arthrosis, myalgia, tendon rupture, tenosynovitis, bone pain, myasthenia, synovitis. Nervous: ataxia, hypertonia, neuralgia, neuropathy, paresthesia, tremor, vertigo, depression, insomnia, somnolence, abnormal dreams, reflexes decreased, hypesthesia. Respiratory: asthma, dyspnea, laryngitis, pharyngitis, sinusitis, bronchitis, sputum increased, cough increased. Skin and Appendages: urticaria, herpes simplex, pruritus, sweating, skin ulcer, contact dermatitis, exfoliative dermatitis. Special Senses: sudden decrease or loss of hearing, mydriasis, conjunctivitis, photophobia, tinnitus, eye pain, ear pain, eye hemorrhage, cataract, dry eyes. Urogenital: cystitis, nocturia, urinary frequency, breast enlargement, urinary incontinence, abnormal ejaculation, genital edema and anorgasmia. Analysis of the safety database from controlled clinical trials showed no apparent difference in adverse reactions in patients taking sildenafil with and without anti-hypertensive medication. This analysis was performed retrospectively, and was not powered to detect any pre-specified difference in adverse reactions. 6.2 Postmarketing Experience The following adverse reactions have been identified during post approval use of sildenafil . Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. These events have been chosen for inclusion either due to their seriousness, reporting frequency, lack of clear alternative causation, or a combination of these factors. Cardiovascular and cerebrovascular Serious cardiovascular, cerebrovascular, and vascular events, including myocardial infarction, sudden cardiac death, ventricular arrhythmia, cerebrovascular hemorrhage, transient ischemic attack, hypertension, subarachnoid and intracerebral hemorrhages, and pulmonary hemorrhage have been reported post-marketing in temporal association with the use of sildenafil. Most, but not all, of these patients had preexisting cardiovascular risk factors. Many of these events were reported to occur during or shortly after sexual activity, and a few were reported to occur shortly after the use of sildenafil without sexual activity. Others were reported to have occurred hours to days after the use of sildenafil and sexual activity. It is not possible to determine whether these events are related directly to sildenafil, to sexual activity, to the patient’s underlying cardiovascular disease, to a combination of these factors, or to other factors [ see Warnings and Precautions (5.1) and Patient Counseling Information (17) ]. Hemic and Lymphatic: vaso-occlusive crisis: In a small, prematurely terminated study of REVATIO (sildenafil) in patients with pulmonary arterial hypertension (PAH) secondary to sickle cell disease, vaso-occlusive crises requiring hospitalization were more commonly reported in patients who received sildenafil than in those randomized to placebo. The clinical relevance of this finding to men treated with sildenafil for ED is not known. Nervous: seizure, seizure recurrence, anxiety, and transient global amnesia. Respiratory: epistaxis Special senses: Hearing: Cases of sudden decrease or loss of hearing have been reported postmarketing in temporal association with the use of PDE5 inhibitors, including sildenafil. In some of the cases, medical conditions and other factors were reported that may have also played a role in the otologic adverse events. In many cases, medical follow-up information was limited. It is not possible to determine whether these reported events are related directly to the use of sildenafil, to the patient’s underlying risk factors for hearing loss, a combination of these factors, or to other factors [ see Warnings and Precautions (5.4) and Patient Counseling Information (17) ]. Ocular: diplopia, temporary vision loss/decreased vision, ocular redness or bloodshot appearance, ocular burning, ocular swelling/pressure, increased intraocular pressure, retinal edema, retinal vascular disease or bleeding, and vitreous traction/detachment. Non-arteritic anterior ischemic optic neuropathy (NAION), a cause of decreased vision including permanent loss of vision, has been reported rarely post-marketing in temporal association with the use of phosphodiesterase type 5 (PDE5) inhibitors, including sildenafil. Most, but not all, of these patients had underlying anatomic or vascular risk factors for developing NAION, including but not necessarily limited to: low cup to disc ratio (“crowded disc”), age over 50, diabetes, hypertension, coronary artery disease, hyperlipidemia and smoking [ see Warnings and Precautions (5.3) and Patient Counseling Information (17) ]. Urogenital: prolonged erection, priapism [ see Warnings and Precautions (5.2) and Patient Counseling Information (17) ], and hematuria.

8.1 Pregnancy Risk Summary Sildenafil is not indicated for use in females. There are no data with the use of sildenafil in pregnant women to inform any drug-associated risks for adverse developmental outcomes. Animal reproduction studies conducted with sildenafil did not show adverse developmental outcomes when administered during organogenesis in rats and rabbits at oral doses up to 16 and 32 times, respectively, the maximum recommended human dose (MRHD) of 100 mg/day on a mg/m 2 basis ( see Data ). Data Animal Data No evidence of teratogenicity, embryotoxicity or fetotoxicity was observed in rats and rabbits which received oral doses up to 200 mg/kg/day during organogenesis. These doses represent, respectively, about 16 and 32 times the MRHD on a mg/m 2 basis in a 50 kg subject. In the rat pre- and postnatal development study, the no observed adverse effect dose was 30 mg/kg/day given for 36 days, about 2 times the MRHD on a mg/m 2 basis in a 50 kg subject.