Duration of Action of Sildenafil Citrate in Men with Erectile Dysfunction

Department of Urology, Southmead Hospital, Westbury-on-Trym, Bristol, UK.
Journal of Sexual Medicine (Impact Factor: 3.15). 10/2004; 1(2):179-84. DOI: 10.1111/j.1743-6109.2004.04026.x
Source: PubMed


Viagra (sildenafil citrate) has a rapid onset of action for the treatment of erectile dysfunction (ED). However, its duration of action has not been thoroughly investigated. Practical knowledge of the time window available for sexual intercourse would be valuable for couples planning sexual activity.
We investigated the duration of action of sildenafil in men with ED.
This was a double-blind, randomized, placebo-controlled, four-way crossover study of 16 men, mean age of 55 years (range, 36-68 years) with ED of no known organic cause. Participants received oral sildenafil (100 mg) or placebo 1, 8, or 12 hours before visual sexual stimulation (VSS). Measurements included the duration of erections of >or= 60% rigidity, assessed by penile plethysmography (RigiScan), and the proportion of sildenafil responders, defined as patients with erections of >or= 60% rigidity for >or= 4 minutes and >or= 50% improvement over erections achieved in their placebo arm. Self-assessed duration of grade 3 (hard enough for penetration) or grade 4 (fully hard) erections was also recorded.
At 1, 8, and 12 hours after dosing with sildenafil, the mean duration of erections with >or= 60% rigidity was 26, 11, and 8 minutes, respectively, compared with only 3 minutes after placebo dosing (P < 0.05). However, the mean duration of self-assessed erections was 33, 23, and 16 minutes, respectively, compared with 7 minutes after placebo dosing (P < 0.05), and was greater than that assessed by RigiScan. Of the 69% sildenafil responders at 1 hour, 82% responded at 8 hours and 45% responded at 12 hours after sildenafil administration.
Sildenafil improved objective and self-assessed erectile function in men with ED, and the duration of action of sildenafil was longer than that previously reported. These data suggest that sildenafil may be effective in a significant proportion of men with ED up to 12 hours after being taken.

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    • "High-fat meals contribute to a reduced rate of absorption by nearly one hour and a 29% decrease in systemic exposure of sildenafil. The plasma half-life of sildenafil is approximately 4 hours and the duration of action is nearly 12 hours.8 "
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    ABSTRACT: Avanafil is a medication that was recently approved by the US Food and Drug Administration for the management of erectile dysfunction. Avanafil is a new phosphodiesterase type 5 inhibitor similar to sildenafil and tadalafil. Avanafil was studied in over 1300 patients during clinical trials, including patients with diabetes mellitus and those who had undergone radical prostatectomy, and was found to be more effective than placebo in all men who were randomized to the drug. The medication was studied with on-demand dosing that may occur after food and/or alcohol. Avanafil is dosed as 50 mg, 100 mg, or 200 mg tablets. Avanafil may differentiate itself from the other phosphodiesterase type 5 inhibitors with its quicker onset and higher specificity for phosphodiesterase type 5 versus other phosphodiesterase subtypes, but may lead to complications of therapy.
    Vascular Health and Risk Management 08/2012; 8(1):517-23. DOI:10.2147/VHRM.S26712
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    • "Sildenafil (Viagra®, Pfizer Inc, New York, NY) is rapidly absorbed from the gut to reach the peak plasma concentration within 1 hour.8,9 Its half-life (t1/2) is 3–5 hours, with duration of action up to 12 hours.10 The time to peak concentration (Tmax) is reduced with high fatty meal consumption. "
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    ABSTRACT: The treatment of erectile dysfunction (ED) has been revolutionized in the last 15 years with the introduction of type 5 phosphodiesterase (PDE5) inhibitors. Their efficacy, safety, and ease of administration have made them first-line treatment for ED. This article reviews the current therapies available for ED, and the new PDE5 inhibitors that are being investigated. Furthermore, it examines all the current ED treatment options that are in different phases of development (including oral and topical pharmacotherapy, gene therapy, and tissue engineering). A special emphasis is on avanafil, a new PDE5 inhibitor that has been studied extensively in Phase I and II clinical trials and has undergone several Phase III trials. Avanafil is a promising medication for ED due to its favorable pharmacokinetics, safety, and efficacy.
    Drug Design, Development and Therapy 10/2011; 5:435-43. DOI:10.2147/DDDT.S15852 · 3.03 Impact Factor
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    ABSTRACT: Background and Aims: Honeymoon impotence or first night erectile dysfunction (ED) is one kind of psychogenic ED which is not uncommon. Prevalence of this kind of ED is higher in conservative communities especially the Muslim population. We assessed the role of Sildenafil, a phosphodiesterase inhibitor (PDE-5) in the management of honeymoon (psychogenic) impotence. Methods: All patients having erectile dysfunction (ED) after marriage with normal nocturnal erections were enrolled in this prospective study from 01-09-2006 to 31-08-2008. Reassurance & Sildenafil 100 mg at bed time was given to every patient and dose reduced to 50 mg after 3 successful intercourses. Patients who did not respond to PDE-5 inhibitor (3 doses), were given intracavernosal injection alprostadil and shifted to PDE-5 inhibitor after successful intercourse. Results: Total number of patients was 45 with age range of 20-39 years. Mean duration elapsed before seeking medical advice was 10±14 days. Eighty percent patients had successful intercourse on first dose of Sildenafil with 95% confidence interval (CI) and 13% patients responded to 2nd dose of Sildenafil. Twelve
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