(094) Synergy Between Orally Administered Phosphodiesterase-type-5-inhibitors and Topically Delivered Nitric-oxide in Eliciting Erectile Responses

Abstract Introduction Phosphodiesterase-type-5-inhibitors (PDE5i) represent first-line FDA-approved oral treatments for erectile dysfunction (ED). However, because their mode of action is dependent on the production of nitric oxide (NO) from nerve endings, patients that suffer neurogenic ED (for exa...

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Published in:Journal of sexual medicine 2023-05, Vol.20 (Supplement_1)
Main Authors: Davies, K, Tar, M, Draganski, A
Format: Article
Language:English
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Summary:Abstract Introduction Phosphodiesterase-type-5-inhibitors (PDE5i) represent first-line FDA-approved oral treatments for erectile dysfunction (ED). However, because their mode of action is dependent on the production of nitric oxide (NO) from nerve endings, patients that suffer neurogenic ED (for example, following the procedures for radical prostatectomy (RP) or resulting from diabetes) are commonly refractory to PDE5i treatment. We recently demonstrated proof-of-principle for increased efficacy of topically applied NO-releasing microparticles (NO-MP) in eliciting an erectile response when used in combination with the orally administered PDE5i, sildenafil. However, there are several other FDA approved PDE5i used to treat ED, which, although acting through the common mechanism of PDE5 inhibition, exhibit several characteristics that potentially could impact clinical and commercial translation of combination therapy. Objective The goal of the present studies was to determine if other commercially available PDE5i besides sildenafil (avanafil, tadalafil and vardenafil) also act cooperatively when used in combination with NO-MP to elicit an erectile response. Methods Sprague-Dawley rats underwent bi-lateral transection of the cavernous nerve (CN), as a model of RP, one-week prior to determining erectile response to treatment. We investigated the effect of oral administration of 0.05mg sildenafil/kg, 0.005mg tadalafil/kg, 0.01mg vardenafil/kg and 0.1mg avanafil/kg (approximately equivalent to clinical doses of 2.5mg, 0.25mg, 0.5mg and 5mg, respectively, administered to an 80 kg patient) 30 minutes prior to being anesthetized for the determination of erectile response by intracorporal pressure (ICP) and systemic blood pressure (BP). Baseline ICP and BP were recorded for 30 minutes, at which time 100 mg of NO-MP (or control, blank-MP) were applied to the rat penile shaft. The ICP and systemic BP were used to determine the time to the first erectile response, duration of the erectile responses, the maximal and average ICP/BP responses and the number of spontaneous erections per hour. Results Although oral treatment by PDE5i alone resulted in no observable erectile response, topical application of NO-MP resulted in spontaneous erectile responses. When NO-MP were applied in combination with oral PDE5i treatment, all PDE5i resulted in faster times to the first erectile response (on average 11 minutes compared to 22 minutes when NO-MP were used alone; P-value=0.041) an
ISSN:1743-6095
1743-6109
DOI:10.1093/jsxmed/qdad060.089