4 CONTRAINDICATIONS
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:epistaxisSpecial 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.
- Certain foods and drinks, like high-fat meals or alcohol, may delay sildenafil’s absorption.
- For best results, take the pill with a light meal or on an empty stomach.
- Adequate hydration can also support optimal absorption.
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.
8.1 Pregnancy
Sildenafil: the science
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) andPatient Counseling Information (17)], and hematuria.
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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. 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. Table 1: Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Fixed-Dose Phase II/III Studies † 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: Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Flexible-Dose Phase II/III Studies Body as a Whole:face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury. The following adverse reactions have been identified during post approval use of sildenafil . 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.
| Use Area | Description |
|---|---|
| Erectile Dysfunction (ED) | Enhances blood flow to achieve erection |
| Pulmonary Hypertension (PAH) | Lowers blood pressure in lungs |
| Off-label Uses | Altitude sickness, Raynaud’s phenomenon |
7 DRUG INTERACTIONS 7.1 NitratesAdministration 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 [ seeDosage and Administration (2.3),Contraindications (4.1),Clinical Pharmacology (12.2)].7.2 Alpha-blockersUse 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 AmlodipineWhen 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 inhibitorsCo-administration of ritonavir, a strong CYP3A4 150mg sildenafil for sale inhibitor, greatly increased the systemic exposure of sildenafil (11-fold increase in AUC).
12.1 Mechanism of Action
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 maxand AUC, respectively. Co-administration of saquinavir, a strong CYP3A4 inhibitor, resulted in 140% and 210% increases in sildenafil C maxand 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 AlcoholIn 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 [ seeClinical Pharmacology (12.2)].
| Parameter | Details |
|---|---|
| Peak Plasma Time | About 30-120 minutes |
| Half-life | Approximately 4 hours |
| Absorption | Fast, with or without food |
| Metabolism | Liver (mainly via CYP3A4) |
| Excretion | Mainly in feces, some in urine |
Administration of sildenafil with nitric oxide donors such as organic nitrates or organic nitrites in any form is contraindicated.
| Condition | Explanation |
|---|---|
| Nitrate Use | Avoid due to risk of severe hypotension |
| Heart Conditions | Caution in unstable angina or recent MI |
| Retinal Disorders | Caution, especially in hereditary degenerations |
| Allergies | Do not use if allergic to sildenafil or related drugs |
Consistent with its known effects on the nitric oxide/cGMP pathway, sildenafil was shown to potentiate the hypotensive effects of nitrates [ seeDosage and Administration (2.3),Contraindications (4.1),Clinical Pharmacology (12.2)]. 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)]. 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)]. Co-administration of ritonavir, a strong CYP3A4 inhibitor, greatly increased the systemic exposure of sildenafil (11-fold increase in AUC).
- Overuse or misuse of sildenafil can lead to adverse effects like priapism or cardiovascular issues.
- It is important to adhere strictly to prescribed dosages.
- Emergency medical attention is needed if painful erections occur.
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)]. 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 [ seeClinical Pharmacology (12.2)].
4.1 Nitrates
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 2basis ( see Data).DataAnimal DataNo 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 2basis in a 50 kg subject.
Drug Interactions
Marketing and sales
8 USE IN SPECIFIC POPULATIONS 8.1 PregnancyRisk SummarySildenafil 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 2basis ( see Data).DataAnimal DataNo evidence of teratogenicity, embryotoxicity or fetotoxicity was observed in rats and rabbits which received oral doses up to 200 mg/kg/day during organogenesis.
2.5 Dosage Adjustments in Special Populations
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:epistaxisSpecial 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.
Pulmonary hypertension
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) andPatient Counseling Information (17)], and hematuria. 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. 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.
Patient resources
Table 1: Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Fixed-Dose Phase II/III Studies † 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: Adverse Reactions Reported by ≥2% of Patients Treated with sildenafil and More Frequent than Placebo in Flexible-Dose Phase II/III Studies Body as a Whole:face edema, photosensitivity reaction, shock, asthenia, pain, chills, accidental fall, abdominal pain, allergic reaction, chest pain, accidental injury. The following adverse reactions have been identified during post approval use of sildenafil . 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. 7 DRUG INTERACTIONS 7.1 NitratesAdministration of sildenafil with nitric oxide donors such as organic nitrates or organic nitrites in any form is contraindicated. These doses represent, respectively, about 16 and 32 times the MRHD on a mg/m 2basis in a 50 kg subject.
Route of administration
Consistent with its known effects on the nitric oxide/cGMP pathway, sildenafil was shown to potentiate the hypotensive effects of nitrates [ seeDosage and Administration (2.3),Contraindications (4.1),Clinical Pharmacology (12.2)].7.2 Alpha-blockersUse 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 AmlodipineWhen 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 inhibitorsCo-administration of ritonavir, a strong CYP3A4 150mg sildenafil for sale 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 maxand AUC, respectively. Co-administration of saquinavir, a strong CYP3A4 inhibitor, resulted in 140% and 210% increases in sildenafil C maxand AUC, respectively. Stronger CYP3A4 inhibitors such as ketoconazole or itraconazole could be expected to have greater effects than seen with saquinavir.
Does sildenafil interact with foods or drinks?
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 AlcoholIn 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 [ seeClinical Pharmacology (12.2)]. 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 [ seeDosage and Administration (2.3),Contraindications (4.1),Clinical Pharmacology (12.2)]. 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)].
Sildenafil Citrate
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)]. 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)]. 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 [ seeClinical Pharmacology (12.2)]. 8 USE IN SPECIFIC POPULATIONS 8.1 PregnancyRisk SummarySildenafil 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.
