5 WARNINGS AND PRECAUTIONS

Key Takeaways…
Usual Adult Dose for Erectile Dysfunction
What can cause erectile dysfunction?
The Real Reasons Sildenafil Doesn’t Work
Common Side Effects of Sildenafil

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 ReactionsSildenafil tablets are contraindicated in patients with a known hypersensitivity to sildenafil, as contained in sildenafil tablets and REVATIO (sildenafil citrate), or any component of the tablet. Hypersensitivity reactions have been reported, including rash and urticaria [ see Adverse Reactions (6.1)]. 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)].

Always use sildenafil 25mg as prescribed by your healthcare provider.
Avoid driving or operating machinery until effects are known.
Sildenafil does not protect against sexually transmitted infections.
Do not share your medication with others.
Report any allergic reactions like rash or swelling.
Use caution to prevent falls or injuries due to dizziness.

Key Takeaways…

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.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 PriapismProlonged 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 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 cell or related anemias.5.3 Effects on the EyePhysicians 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 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.

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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).

Usual Adult Dose for Erectile Dysfunction

Missed Dose

Sildenafil tablets are contraindicated in patients with a known hypersensitivity to sildenafil, as contained in sildenafil tablets and REVATIO (sildenafil citrate), or any component of the tablet. 5 WARNINGS AND PRECAUTIONS 5.1 CardiovascularThere is a potential for cardiac risk of sexual activity in patients with preexisting cardiovascular disease. 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. 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 tablets has systemic vasodilatory properties that resulted in transient sildenafil citrate sublingual tablets 100mg 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.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 PriapismProlonged 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.

What should I tell my healthcare provider before taking sildenafil?

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 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 cell or related anemias.5.3 Effects on the EyePhysicians 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 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. Other risk factors for NAION, such as the presence of "crowded" optic disc, may have contributed to the occurrence of NAION in these studies.

What can cause erectile dysfunction?

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.

Dangerous Interactions

Individuals who have already experienced NAION are at increased risk of NAION recurrence. 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.5.4 Hearing LossPhysicians 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 sildenafil softgel capsule 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) ].5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensivesCaution is advised when PDE5 inhibitors are co-administered with alpha-blockers.

Alcohol interaction warning

PDE5 inhibitors, including sildenafil tablets 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.Sildenafil tablets 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 tablets, 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 Clinical Pharmacology (12.2)].5.6 Adverse Reactions with the Concomitant Use of RitonavirThe concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC). 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 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.5.4 Hearing LossPhysicians 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 sildenafil softgel capsule 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) ].5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensivesCaution 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.

Indication	Description	Approved by FDA	Off-label Use
Erectile Dysfunction	Helps achieve and maintain erections	Yes	Yes
Pulmonary Arterial Hypertension	Off-label for vasodilation	No	Yes
Raynaud’s Phenomenon	Used off-label to improve blood flow	No	Yes

When vasodilators are used in combination, an additive effect on blood pressure may occur.

Use sildenafil 25mg as part of a comprehensive ED treatment plan.
Sexual stimulation is needed for the drug to be effective.
Do not take sildenafil if you have heart issues without consulting a doctor.
The medication can cause a temporary vision change.
Limit physical activity after taking the medication to avoid dizziness.
Use with caution if you are taking blood pressure medications.

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.

The Real Reasons Sildenafil Doesn’t Work

If sildenafil tablets are 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 TherapiesThe safety and efficacy of combinations of sildenafil tablets 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.

Why this range helps:

Sildenafil side effects

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.

Parameter	Value	Notes
Absorption	Rapid, within 30-60 minutes	Peak plasma levels occur at this time
Bioavailability	Approximately 40%	Due to first-pass metabolism
Half-life	4-5 hours	Duration of effect
Metabolism	Liver via CYP3A4 enzyme	Variability based on liver function
Excretion	Mainly in feces, some in urine	Clearance mostly hepatic

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.Sildenafil tablets 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 tablets, 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 Clinical Pharmacology (12.2)].5.6 Adverse Reactions with the Concomitant Use of RitonavirThe concomitant administration of the protease inhibitor ritonavir substantially increases serum concentrations of sildenafil (11-fold increase in AUC). If sildenafil tablets are prescribed to patients taking ritonavir, caution should be used.

Common Side Effects of Sildenafil

Why it’s 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 TherapiesThe safety and efficacy of combinations of sildenafil tablets 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.