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Figure 6 shows that regardless of the baseline levels of function, subsequent function in patients treated with VIAGRA was better than that seen in patients treated with placebo. At the same time, on-treatment function was better in treated patients who were less impaired at baseline. Sildenafil at steady state, at a dose not approved for the treatment of erectile dysfunction (80 mg t.i.d.) resulted in a 50% increase in AUC and a 42% increase in C max of bosentan (125 mg b.i.d.). Pharmacokinetic data from patients in clinical trials showed no effect on sildenafil pharmacokinetics of CYP2C9 inhibitors , CYP2D6 inhibitors , thiazide and related diuretics, ACE inhibitors, and calcium channel blockers. The AUC of the active metabolite, N-desmethyl sildenafil, was increased 62% by loop and potassium-sparing diuretics and 102% by nonspecific beta-blockers. These effects on the metabolite are not expected to be of clinical consequence. Sildenafil is cleared predominantly by the CYP3A4 and CYP2C9 hepatic microsomal isoenzymes.

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The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. This metabolite has a PDE selectivity profile similar to sildenafil and an in vitro potency for PDE5 approximately 50% of the parent drug. Plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil, so that the metabolite accounts for about 20% of sildenafil’s pharmacologic effects. VIAGRA is rapidly absorbed after oral administration, with a mean absolute bioavailability of 41% (range 2563%). It is eliminated predominantly by hepatic metabolism and is converted to an active metabolite with properties similar to the parent, sildenafil. Both sildenafil and the metabolite have terminal half lives of about 4 hours.

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In volunteers with hepatic impairment (Child-Pugh Class A and B), sildenafil clearance was reduced, resulting in higher plasma exposure of sildenafil (47% for C max and 85% for AUC). The pharmacokinetics of sildenafil in patients with severely impaired hepatic function (Child-Pugh Class C) have not been studied. A starting dose of 25 mg should be considered in patients with any degree of hepatic impairment . Sildenafil was not carcinogenic when administered to mice for months at dosages up to the Maximum Tolerated Dose of 10 mg/kg/day, approximately 0.6 times the MRHD on a mg/m² basis.

When VIAGRA 100 mg oral was co-administered with amlodipine, 5 mg or 10 mg oral, to hypertensive patients, the mean additional reduction on supine blood pressure was 8 mmHg systolic and 7 mmHg diastolic. In the third study, a single oral dose of VIAGRA 100 mg or matching placebo was administered in a 3-period crossover design to 20 generally healthy males with BPH. Treatment with doxazosin continued for at least 7 days after dose period 1. PDE5 inhibitors, including VIAGRA, may potentiate the hypotensive effects of GC stimulators. Hypersensitivity reactions have been reported, including rash and urticaria .

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You may find that one works better for your schedule or that there are differences in the side effects for you. But these medications work the same basic way, so you’re likely to have similar results.

The FDA has approved several prescription drugs you take orally to treat ED. Stop taking VIAGRA and call your healthcare provider right away if you have sudden vision loss in one or both eyes. medicines called alpha blockers such as Hytrin , Flomax , Cardura , Minipress , Uroxatral , Jalyn , or Rapaflo . Alpha-blockers are sometimes prescribed for prostate problems or high blood pressure. Results with all doses have been pooled, but scores showed greater improvement at the 50 and 100 mg doses than at 25 mg. The pattern of responses was similar for the other principal question, the ability to achieve an erection sufficient for intercourse. The titration studies, in which most patients received 100 mg, showed similar results.

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Katz said the first thing a man should do is have a proper physical from a primary care physician. Impotence can be the first sign of heart disease, particularly in younger men, he said. Generic versions “will be of real benefit to the majority of men,” he said.

  • Similar effects on blood pressure were noted with 25 mg, 50 mg and 100 mg of VIAGRA, therefore the effects are not related to dose or plasma levels within this dosage range.
  • If you experience a sudden loss of hearing, sometimes with ringing in the ears or dizziness, while you are taking sildenafil, call your doctor immediately.
  • The decrease in sitting blood pressure was most notable approximately 1-2 hours after dosing, and was not different than placebo at 8 hours.
  • If you are taking sildenafil for erectile dysfunction, do not take any more doses of sildenafil or similar medications such as tadalafil or vardenafil until you talk to your doctor.
  • Some patients experienced a sudden decrease or loss of hearing after they took sildenafil or other medications that are similar to sildenafil.
  • If you are taking sildenafil for PAH, do not stop taking your medication until you talk to your doctor.