Sildenafil (Page 2 of 8)

5.4 Hearing Loss

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)].

5.5 Hypotension when Co-administered with Alpha-blockers or Anti-hypertensives

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. 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 have 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 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 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 to 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 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. 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 tablets. A causal relationship between sildenafil tablets and these events has not been established. In humans, sildenafil tablets have 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 tablets had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans. The safety of sildenafil tablets 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 tablets 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.


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.

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 tablets were administered to over 3700 patients (aged 19 to 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 tablets (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 with Sildenafil Tablets and More Frequently 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 tablets were 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 tablets at least once weekly, and the following adverse reactions were reported:Table 2. Adverse Reactions Reported by ≥2% of Patients Treated with Sildenafil Tablets and More Frequent than Placebo in Flexible-Dose Phase II/III Studies

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 tablets 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 tablets with and without anti-hypertensive medication. This analysis was performed retrospectively, and was not powered to detect any pre-specified difference in adverse reactions.

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