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VIAGRA (sildenafil citrate) Warnings And Precautions

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Warnings And Precautions

General

The evaluation of erectile dysfunction should include a determination of potential underlying causes and the identification of appropriate treatment following a complete medical assessment.

Cardiovascular

As with all treatments for erectile dysfunction, there is a potential cardiac risk of sexual activity in patients with pre-existing cardiovascular disease, including hypertension (BP>140/90). Therefore, treatments for erectile dysfunction, including VIAGRA (sildenafil citrate), should not be generally administered in men for whom sexual activity is inadvisable because of their underlying cardiovascular status.

There are no controlled clinical data on the safety or efficacy of VIAGRA 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 at rest) or hypertension (BP >170/110 at rest)
  • Patients with cardiac failure or coronary artery disease causing unstable angina

(see ACTION AND CLINICAL PHARMACOLOGY)

Caution is advised when sildenafil is administered to patients taking an alpha-blocker, as the coadministration may lead to symptomatic hypotension in a few susceptible individuals (see DRUG INTERACTIONS). In order to minimize the potential for developing postural hypotension, patients should be hemodynamically stable on alpha-blocker therapy prior to initiating sildenafil treatment. Initiation of sildenafil at lower doses should be considered. In addition, physicians should advise patients what to do in the event of postural hypotensive symptoms.

Hematologic

In clinical trials, sildenafil has been shown to have systemic vasodilatory properties that result in transient decreases in blood pressure (see DETAILED PHARMACOLOGY). This is of little or no consequence in most patients. However, prior to prescribing sildenafil, physicians should carefully consider whether their patients with certain underlying conditions could be adversely affected by such vasodilatory effects, especially in combination with sexual activity. Patients with increased susceptibility to vasodilators include those with left ventricular outflow obstruction (e.g., aortic stenosis, hypertrophic obstructive cardiomyopathy), or those with the rare syndrome of multiple system atrophy manifesting as severely impaired autonomic control of blood pressure.

In humans, VIAGRA (sildenafil citrate) has no effect on bleeding time when taken alone or with acetylsalicylic acid. In vitro studies with human platelets indicate that sildenafil potentiates the antiaggregatory effect of sodium nitroprusside (a nitric oxide donor). The combination of heparin and VIAGRA had an additive effect on bleeding time in the anesthetized rabbit, but this interaction has not been studied in humans (see ACTION AND CLINICAL PHARMACOLOGY).

There is no safety information on the administration of VIAGRA to patients with bleeding disorders or active peptic ulceration. Therefore, VIAGRA should be administered with caution to these patients.

Hepatic/Biliary/Pancreatic

In volunteers with hepatic cirrhosis (Child-Pugh A and B), sildenafil clearance was reduced, resulting in increases in AUC (84%) and Cmax (47%) compared to age-matched volunteers with no hepatic impairment.

A starting dose of 25 mg should be considered in patients with hepatic impairment (see ACTION AND CLINICAL PHARMACOLOGY, DOSAGE AND ADMINISTRATION).

Ophthalmologic

Patients should stop taking PDE5 inhibitors, including VIAGRA, and consult their physician immediately if they experience a decrease in, or sudden loss of, vision in one or both eyes. Postmarketing reports of sudden loss of vision have occurred rarely, in temporal association with the use of PDE5 inhibitors. An observational study evaluated whether recent use of PDE5 inhibitors, as a class, was associated with acute onset of NAION. The results suggest an approximate 2-fold increase in the risk of NAION within 5 half-lives of PDE5 inhibitor use.

Individuals who have already experienced NAION are at increased risk of NAION recurrence. PDE 5 inhibitors, including VIAGRA, are not recommended in patients with male erectile dysfunction with a previous episode of NAION (see CONTRAINDICATIONS). There are no controlled clinical data on the safety or efficacy of VIAGRA in patients with retinitis pigmentosa (a minority of these patients have genetic disorders of retinal phosphodiesterases). If prescribed, this should be done with caution. (see ACTION AND CLINICAL PHARMACOLOGY).

A small percentage of patients experience visual effects (e.g. impairment of colour discrimination, increased perception to light, blurred vision, eye pain, ocular redness) after taking VIAGRA. If this happens, then the patient should not operate a motor vehicle or any heavy machinery until the adverse effects disappear (see ACTION AND CLINICAL PHARMACOLOGY).

Rare cases of central serous chorioretinopathy have been reported during the post-marketing period in temporal association with the use of sildenafil citrate. It is not known if medical and other facts were reported that may have also played a role in the development of the condition. It is not possible to determine whether the development of the condition was related directly to the use of sildenafil, to the patient’s possible underlying risk factors, a combination of these factors, or to other factors. These cases of central serous chorioretinopathy in patients receiving sildenafil did not provide evidence of serious or permanent alteration in visual function. (See POST-MARKET ADVERSE DRUG REACTIONS).

Otologic

Sudden decrease or loss of hearing has been reported in a few number of postmarketing and clinical trials cases with the use of PDE5 inhibitors, including VIAGRA. These events, which may be accompanied by tinnitus and dizziness, have been reported in temporal association to the intake of PDE5 inhibitors, including VIAGRA. 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 events are related directly to the use of PDE5 inhibitors or to other factors (see ADVERSE REACTIONS, POST-MARKET ADVERSE DRUG REACTIONS and PART III CONSUMER INFORMATION). Physicians should advise patients to stop taking VIAGRA and seek prompt medical attention in case of sudden decrease or loss of hearing.

Renal

In volunteers with mild (CLcr = 50-80 mL/min) and moderate (CLcr = 30-49 mL/min) renal impairment, the pharmacokinetics of a single oral dose of VIAGRA (50 mg) was not altered. In volunteers with severe (CLcr <30 mL/min) renal impairment, sildenafil clearance was reduced, resulting in increases in AUC (100%) and Cmax (88%) compared to age-matched volunteers with no renal impairment.

A starting dose of 25 mg should be considered in patients with severe renal impairment (see ACTION AND CLINICAL PHARMACOLOGY, DOSAGE AND ADMINISTRATION).

Sexual Function/Reproduction

Although priapism had not been reported during clinical trials, prolonged erection greater than 4 hours and priapism (painful erections greater than 6 hours in duration) have been reported infrequently during the post-marketing surveillance of VIAGRA. 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 (see ADVERSE REACTIONS).

Agents for the treatment of erectile dysfunction 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).

The safety and efficacy of combinations of VIAGRA with other PDE5 inhibitors, or other pulmonary arterial hypertension (PAH) treatments containing sildenafil (REVATIO), or other agents for the treatment of erectile dysfunction have not been studied. Therefore, the use of such combinations is not recommended.

Skin/Appendages

Rare cases of Stevens-Johnson’s Syndrome (SJS) and Toxic Epidermal Necrolysis (TEN) have been reported during the post-marketing period.

Special Populations

Women, Nursing Mothers, Pregnancy: VIAGRA is not indicated for use in women. There are no adequate and well-controlled studies in pregnant or lactating women.

Pediatrics: VIAGRA is not indicated for use in children.

Geriatrics (> 65 years of age): Healthy elderly volunteers had a reduced clearance of sildenafil, with free plasma concentrations approximately 40% greater than those seen in younger volunteers (18 to 45 years). Since higher plasma levels may increase both the pharmacological action and incidence of some adverse events, a starting dose of 25 mg should be considered (see ACTION AND CLINICAL PHARMACOLOGY, DOSAGE AND ADMINISTRATION).

Driving and Operating Machinery: As dizziness and altered vision were reported in clinical trials with sildenafil, patients should be aware of how they react to VIAGRA, before driving or operating machinery. The effect of sildenafil on the ability to drive and use machinery has not been studied.