The type of adverse reactions in flexible-dose studies, which reflect the recommended dosage regimen, was similar to that for fixed-dose studies. Sildenafil at recommended doses has no effect in the absence of sexual stimulation. Twenty subjects received Fildena 50 mg, but only 19 subjects received matching placebo. While there were no severe adverse events potentially related to blood pressure reported in this study, one subject reported moderate vasodilatation after both Fildena 50 mg and 100 mg. There were no episodes of syncope reported in this study.
In a double-blind study, 144 patients with erectile dysfunction and chronic stable angina limited by exercise, not receiving chronic oral nitrates, were randomized to a single dose of placebo or Fildena 100 mg 1 hour prior to exercise testing. Mean sildenafil plasma concentrations measured after the administration of a single oral dose of 100 mg to healthy male volunteers is depicted below: The pharmacokinetics of sildenafil in patients with severely impaired hepatic function (Child-Pugh Class C) have not been studied see DOSAGE AND ADMINISTRATION , and Use in Specific Populations.
At 24 hours the plasma levels of sildenafil were still approximately 200 ng/mL, compared to approximately 5 ng/mL when sildenafil was dosed alone. Single doses of antacid (magnesium hydroxide/aluminum hydroxide) did not affect the bioavailability of Fildena. Sildenafil is a weak inhibitor of the CYP isoforms 1A2, 2C9, 2C19, 2D6, 2E1 and 3A4 (IC50 > 150 ?M).
In a study of healthy male volunteers, sildenafil (100 mg) did not affect the steady state pharmacokinetics of the HIV protease inhibitors, saquinavir and ritonavir, both of which are CYP3A4 substrates. 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.). Fildena was evaluated primarily at doses of 25 mg, 50 mg and 100 mg in 21 randomized, double-blind, placebo-controlled trials of up to 6 months in duration, using a variety of study designs (https://www.drvolcanoe.com/fildena-side-effects/).
Fildena demonstrated statistically significant improvement compared to placebo in all 21 studies. Also collected as part of the IIEF was information about other aspects of sexual function, including information on erectile function, orgasm , desire, satisfaction with intercourse, and overall sexual satisfaction. 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.
Figure 6 shows that regardless of the baseline levels of function, subsequent function in patients treated with Fildena was better than that seen in patients treated with placebo. The frequency of patients reporting improvement of erections in response to a global question in four of the randomized, double-blind, parallel, placebo-controlled fixed dose studies (1797 patients) of 12 to 24 weeks duration is shown in Figure 7. These patients had erectile dysfunction at baseline that was characterized by median categorical scores of 2 (a few times) on principal IIEF questions.
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