SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Sildenafil

170

The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) signal-transduction pathway is impaired in many cardiovascular diseases, including pulmonary arterial hypertension (PAH). Riociguat (BAY 63-2521) is a stimulator of sGC that works both in synergy with and independently of NO to increase levels of cGMP. The aims of this study were to investigate the role of NO-sGC-cGMP signaling in a model of severe PAH and to evaluate the effects of sGC stimulation by riociguat and PDE5 inhibition by sildenafil on pulmonary hemodynamics and vascular remodeling in severe experimental PAH.

Concepts: Pulmonology, Myocardial infarction, Pulmonary artery, Nitric oxide, Pulmonary hypertension, Guanylate cyclase, Sildenafil, Riociguat

26

Nitric oxide (NO) is a highly reactive radical that acts as a direct or indirect cellular signalling molecule in plant growth, development and environmental responses. Here we studied the contribution of NO to the control of leaflet movements during nyctinastic closure. For this purpose, we tested the effect of NO donors and an NO scavenger, all supplied in light, on Albizia lophantha leaflet closure after transferral to darkness. Exogenous NO, applied as four donors [sodium nitroprusside (SNP), diethylammonium (Z)-1-(N,N-diethylamino) diazen-1-ium-1,2-diolate (DEA-NONOate), S-nitroso-N-acetylpenicillamine (SNAP) and S-nitrosoglutathione (GS-NO)], inhibited nyctinastic leaflet closure while the application of an NO scavenger [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (cPTIO)] plus SNP cancelled the effect of the latter. The inclusion of Nω-nitro-l-arginine methyl ester (l-NAME) or sodium tungstate in the incubation media enhanced nyctinastic closure and also resulted in a decrease in the nitrate plus nitrite released by leaflets into the incubation solution. These results support the notion that NO is involved in regulating the nyctinastic closure of A. lophantha leaflets. Cellular perception of NO did not appear to be mediated by calcium. Pharmacological application of inhibitors of soluble guanylate cyclase (sGC) [1H-[1,2,4]-oxadiazole-[4,3-a]-quinoxalin-1-one (ODQ) and 6-anilino-5,8-quinolinequinone (Ly83583)], phosphodiesterase type 5 (PDE5) (Sildenafil) and the cyclic guanosine monophosphate (cGMP) analogue 8-bromoguanosine-3',5'-cyclomonophosphate sodium salt (8-Br-cGMP) indicated that cGMP was downstream of the NO signalling cascade during nyctinastic closure.

Concepts: Ammonia, Nitric oxide, Salt, Guanylate cyclase, Cyclic guanosine monophosphate, Phosphodiesterase, Sildenafil, Guanosine monophosphate

23

The purpose of this review is to provide an overview of the pharmacology, tolerability, and efficacy of the different phosphodiesterase type 5 (PDE5) inhibitors available for the treatment of erectile dysfunction (ED), with a special focus on the sildenafil orodispersible tablet (ODT) formulation.

Concepts: Pharmacology, Adverse drug reaction, Erectile dysfunction, Cyclic guanosine monophosphate, Citrates, Phosphodiesterase, PDE5 inhibitor, Sildenafil

19

IMPORTANCE The RAS/RAF/mitogen-activated protein kinase and extracellular signal-regulated kinase (ERK) kinase/ERK cascade plays a crucial role in melanoma cell proliferation and survival. Sildenafil citrate (Viagra) is a phosphodiesterase (PDE) 5A inhibitor commonly used for erectile dysfunction. Recent studies have shown that BRAF activation down-regulates PDE5A levels, and low PDE5A expression by BRAF activation or sildenafil use increases the invasiveness of melanoma cells, which raises the possible adverse effect of sildenafil use on melanoma risk. OBJECTIVE To evaluate the association between sildenafil use and risk of incident melanoma among men in the United States. DESIGN, SETTING, AND PARTICIPANTS Our study is a prospective cohort study. In 2000, participants in the Health Professionals' Follow-up Study were questioned regarding sildenafil use for erectile dysfunction. Participants who reported cancers at baseline were excluded. A total of 25 848 men remained in the analysis. MAIN OUTCOMES AND MEASURES The incidence of skin cancers, including melanoma, squamous cell carcinoma (SCC), and basal cell carcinoma (BCC), was obtained in the self-reported questionnaires biennially. The diagnosis of melanoma and SCC was pathologically confirmed. RESULTS We identified 142 melanoma, 580 SCC, and 3030 BCC cases during follow-up (2000-2010). Recent sildenafil use at baseline was significantly associated with an increased risk of subsequent melanoma with a multivariate-adjusted hazard ratio (HR) of 1.84 (95% CI, 1.04-3.22). In contrast, we did not observe an increase in risk of SCC (HR, 0.84; 95% CI, 0.59-1.20) or BCC (1.08; 0.93-1.25) associated with sildenafil use. Moreover, erectile function itself was not associated with an altered risk of melanoma. Ever use of sildenafil was also associated with a higher risk of melanoma (HR, 1.92; 95% CI, 1.14-3.22). A secondary analysis excluding those reporting major chronic diseases at baseline did not appreciably change the findings; the HR of melanoma was 2.24 (95% CI, 1.05-4.78) for sildenafil use at baseline and 2.77 (1.32-5.85) for ever use. CONCLUSIONS AND RELEVANCE Sildenafil use may be associated with an increased risk of developing melanoma. Although this study is insufficient to alter clinical recommendations, we support a need for continued investigation of this association.

Concepts: Signal transduction, Squamous cell carcinoma, Erectile dysfunction, Basal cell carcinoma, Skin cancer, Mohs surgery, Phosphodiesterase, Sildenafil

7

To assess the effect of sildenafil, a phosphodiesterase type 5 inhibitor, on digital ulcer (DU) healing in systemic sclerosis (SSc).

Concepts: Healing, Effectiveness, Rheumatology, Scleroderma, Systemic scleroderma, Sildenafil, Mucinoses

5

Sildenafil increases insulin sensitivity in mice. In humans, phosphodiesterase 5 inhibition improves disposition index, but the mechanism of this effect has not been elucidated and may depend on duration. In addition, increasing cyclic GMP without increasing nitric oxide could have beneficial effects on fibrinolytic balance.

Concepts: Insulin, Nitric oxide, Sildenafil

5

INTRODUCTION: Many products labeled “herbal” or “all natural” (herbal/natural) that claim to enhance sexual performance and imply use for the treatment of erectile dysfunction (ED) are marketed as over-the-counter (OTC) dietary supplements. However, adulteration with undeclared phosphodiesterase type 5 (PDE5) inhibitors appears widespread. AIM: To assess the availability, cost, origin, categorical content, and adulteration with PDE5 inhibitors of purported herbal/natural OTC dietary supplements claiming to naturally enhance sexual performance. METHODS: Pfizer Global Security coordinated sample collection (all from convenience stores and filling stations in two U.S. metropolitan areas except for seven from U.S. Customs seizures) and liquid chromatography/mass spectrometry examination. MAIN OUTCOME MEASURE: Adulteration with synthetic PDE5 inhibitors. RESULTS: Ninety-one samples labeled as 58 distinct products and priced from $2.99 to $17.99 were evaluated. Origin/manufacture was claimed as United States (n = 62), apparently Asian (n = 15), and not clearly identified (n = 14). Although no sample claimed to include synthetic substances, 74 (81%) contained PDE5-inhibitor pharmaceutical ingredients, including tadalafil and/or sildenafil (n = 40, of which 18 contained >110% of the highest approved drug product strength) or PDE5-inhibitor analogs (n = 34). Pronounced heterogeneity of contents between samples within individual products indicated minimal quality control during manufacture. Labeling was inadequate (e.g., lacking lot number and/or expiry date) for 17 products (23 samples) and inconsistent between samples within a given product (e.g., in manufacturer, lot number, and/or expiry date) for seven of 17 products having multiple samples. Only 14 samples warned against concomitant nitrate use. CONCLUSIONS: Ethical pharmaceutical companies are concerned for an unsuspecting public when their products are counterfeited, mislabeled, and illegally offered for sale in an unsafe manner. Because of the dangers of adulteration with synthetic PDE5 inhibitors, absent safety warnings, and lack of quality or consistent manufacture, men with ED unknowingly risk their health by using OTC herbal/natural products that claim to enhance sexual performance. Campbell N, Clark JP, Stecher VJ, Thomas JW, Callanan AC, Donnelly BF, Goldstein I, and Kaminetsky JC. Adulteration of purported herbal and natural sexual performance enhancement dietary supplements with synthetic phosphodiesterase type 5 inhibitors. J Sex Med **;**:**-**.

Concepts: Over-the-counter drug, Erectile dysfunction, Food safety, Phosphodiesterase, PDE5 inhibitor, Sildenafil, PDE5 inhibitors, Vardenafil

3

1

To study the effect of sildenafil citrate on spontaneous passage of distal ureteric stones (DUS).

Concepts: Medicine, Citrates, Sildenafil

1

Orally active, selective inhibitors of phosphodiesterase type 5 (PDE 5, cyclic GMP PDE), such as sildenafil, tadalafil and vardenafil, are currently the first-choice treatment options for the clinical management of erectile dysfunction (ED) of various etiologies and severities. However, a significant number of patients remain dissatisfied with the available therapies due a lack of efficacy or discomfort arising from adverse events. Several new PDE5 inhibitors, among which are avanafil (TA-1790), lodenafil, mirodenafil, udenafil, SLX-2101, JNJ-10280205 and JNJ-10287069, have recently been approved and introduced into the market or are in the final stages of their clinical development. Avanafil (marketed in the US under the brand name STENDRA(™)) has been developed by VIVUS Inc. (Mountain View, CA, USA) and has recently received approval from the US Food and Drug Administration (FDA) for use in the treatment of male ED. The drug has demonstrated improved selectivity for PDE5, is rapidly absorbed after oral administration with a fast onset of action and a plasma half-life that is comparable to sildenfil and vardenafil. In phase II and phase III clinical trials that included a large number of patients, avanafil has been shown to be effective and well tolerated. Owing to its favorable pharmacodynamic and pharmacokinetic profile, avanafil is considered as a promising new option in the treatment of ED. The present article summarizes the initial data and clinical key properties of avanafil.

Concepts: Pharmacology, Clinical trial, Erectile dysfunction, Phosphodiesterase, PDE5 inhibitor, Sildenafil, PDE5 inhibitors, Vardenafil