The following adverse reactions have been identified during post approval use of sildenafil citrate. 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 citrate. 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 citrate without sexual activity. Others were reported to have occurred hours to days after the use of sildenafil citrate and sexual activity. It is not possible to determine whether these events are related directly to sildenafil citrate, 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 sildenafil tablets, 20 mg (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 tablets, 25 mg, 50 mg and 100 mg for ED is not known.
Nervous: seizure, seizure recurrence, anxiety, and transient global amnesia.
Hearing: Cases of sudden decrease or loss of hearing have been reported postmarketing in temporal association with the use of PDE5 inhibitors, including sildenafil citrate. 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 citrate, 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 citrate. 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)].
Administration of sildenafil citrate 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 citrate was shown to potentiate the hypotensive effects of nitrates [ see Dosage and Administration (2.3), Contraindications (4.1), Clinical Pharmacology (12.2)].
Use caution when co-administering alpha-blockers with sildenafil citrate because of potential additive blood pressure-lowering effects. When sildenafil citrate is co-administered with an alpha-blocker, patients should be stable on alpha-blocker therapy prior to initiating sildenafil citrate treatment and sildenafil citrate should be initiated at the lowest dose [ see Dosage and Administration (2.3), Warnings and Precautions (5.5), Clinical Pharmacology (12.2)].
When sildenafil citrate 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 citrate 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 citrate 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)].
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)].
Sildenafil Citrate is not indicated for use in females.
There are no data with the use of Sildenafil Citrate 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).
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