British Society for Sexual Medicine guidelines on the management of erectile dysfunction.

INTRODUCTION: UK primary care physicians are required to follow authoritative endorsed guidelines as part of their terms of service. The major influence on the management of erectile dysfunction in primary and secondary care between 1999 and 2007 has been Department of Health "guidance on good practice," a non-evidence-based document, essentially defining patients who qualify for government-funded treatment. AIM: To provide clinically based guidelines relevant to UK primary and secondary healthcare professionals in their daily practice. METHODS: A multidisciplinary panel of seven UK experts including two primary care physicians from the British Society for Sexual Medicine met for two full day meetings between September 2006 and April 2007, with each member allocated to disease areas related to their specialty. Feedback and approval of all sections between panel members was facilitated by the chairman. Source information was obtained from peer reviewed articles, meetings and presentations. Articles were chosen from electronically searching the Cochrane Library, Medline and Embase for randomized controlled clinical trials and graded according to level of evidence. RESULTS: Patient-reported sexual activity, satisfaction with sexual activity (Male Sexual Health Questionnaire), and treatment expectations; urologists' subjective assessment of the importance given by their patients to ED; the timing they propose for starting ED treatment. RESULTS: After the second full day meeting in January 2007, the final version was approved by panel members and made available for healthcare professions by download from http://www.bssm.org and from http://www.eguidelines.co.uk CONCLUSIONS: A comprehensive evidence-based guideline has been developed that is highly relevant for primary and secondary care professionals enabling them to work within the unique requirements of the UK healthcare system.

A nitric oxide-releasing PDE5 inhibitor relaxes human corpus cavernosum in the absence of endogenous nitric oxide.

INTRODUCTION: In conditions with severe deficiency of endogenous nitric oxide (NO), such as long-term diabetes and cavernosal nerve injury, phosphodiesterase type 5 (PDE5) inhibitors have reduced efficacy in the treatment of erectile dysfunction. NO-releasing PDE5 inhibitors could be an alternative therapeutic approach in such cases. AIM: We therefore aimed to compare sildenafil and NO-releasing sildenafil (NCX-911) in relaxing human corpus cavernosum in the absence or presence of endogenous NO. METHODS: The two compounds were compared in reducing the phenylephrine-induced tone of human corpus cavernosum in the presence or absence of an inhibitor of NO synthase (L-NAME; 500 microM) or an inhibitor of soluble guanylate cyclase (ODQ, 10 microM). RESULTS: NCX-911 was as potent as sildenafil in control conditions (EC(50) = 733.1 +/- 94.4 nM and 800.7 +/- 155.8 nM, respectively). The potency of NCX-911 was not altered but that of sildenafil decreased significantly in the presence of L-NAME (EC(50) = 980.4 +/- 106.7 nM and 2446.7 +/- 256.8 nM, respectively; P < 0.001 for sildenafil vs. control). Both compounds below 1 microM failed to induce relaxation in the presence of ODQ (EC(50) = 6,578 +/- 1150 nM and 6,488 +/- 938 nM for NCX-911 and sildenafil, respectively). CONCLUSION: These results show that the potency of NCX-911 was maintained unlike sildenafil in the absence of endogenous NO confirming the potential use of NO-releasing PDE5 inhibitors in NO-deficient conditions.

A comparative study of sildenafil, NCX-911 and BAY41-2272 on the anococcygeus muscle of diabetic rats.

We compared the effects of a nitric oxide (NO)-releasing sildenafil (NCX-911), NO-independent soluble guanylate cyclase activator (BAY41-2272) and sildenafil on the anococcygeus muscle from streptozotocin-induced 16-weeks diabetic rats. NCX-911, BAY41-2272 and sildenafil reduced the phenylephrine-induced tone in the control group (EC50=1088.8+/-165.0, 151.6+/-9.3 and 827.1+/-167.3 nM, respectively). The potencies of NCX-911 and BAY41-2272 were not altered, but that of sildenafil was significantly reduced in the diabetic group. EC50 values for NCX-911, BAY41-2272 and sildenafil in the diabetic group were 1765.9+/-303.5, 209.7+/-27.3 and 2842.2+/-640.3 nM, respectively (P<0.05 for sildenafil). Nitrergic relaxation responses were significantly decreased in the diabetic group. The remaining nitrergic relaxation responses were potentiated by BAY41-2272 but not by sildenafil or NCX-911. These results confirm that endogenous NO derived from nitrergic nerves is significantly decreased in diabetes, and suggest that NO-releasing PDE5 inhibitors and NO-independent soluble guanylate cyclase activators could be more useful than PDE5 inhibitors in the treatment of ED in long-term diabetes.

Y-27632, a Rho-kinase inhibitor, inhibits proliferation and adrenergic contraction of prostatic smooth muscle cells.

PURPOSE: Benign prostatic hyperplasia (BPH) causes mechanical urinary flow obstruction by 2 components, namely an enlarged prostate (static component) and elevated smooth muscle tone (dynamic component). Currently available treatments for BPH aim to inhibit the proliferation of prostatic cells or decrease the elevated tone. To our knowledge no single agent that can achieve these 2 ends has yet been identified. A specific inhibitor of Rho-kinase, Y-27632 ((+)-(R)-trans-4-(1-aminoethyl)-N-(4-pyridyl)cyclohexanecarboxamide dihydrochloride), has been demonstrated to cause smooth muscle relaxation and inhibit smooth muscle cell proliferation. Therefore, we investigated the effect of Y-27632 on prostatic smooth muscle proliferation and tone. MATERIALS AND METHODS: Rho-kinase expression was investigated by immunocytochemistry and immunoblotting in smooth muscle cells obtained from rat and human prostates. The effect of Y-27632 was examined on the proliferation of these cells and on the contractions elicited by electrical field stimulation and exogenous phenylephrine in rat prostatic strips. RESULTS: Immunoblot and immunofluorescence analysis showed that Rho-kinase is present in the cytosol and located in the perinuclear region in human and rat prostatic smooth muscle cells. Y-27632 decreased the proliferation of human and rat prostatic smooth muscle cells, and inhibited noradrenergic contractions elicited by electrical field stimulation and exogenous phenylephrine in rat prostatic strips (EC50 17.8 +/- 4.8 and 7.8 +/- 2.1 microM, respectively). CONCLUSIONS: To our knowledge we report the first demonstration of the presence of Rho-kinase in prostatic smooth muscle cells, and of the relaxant and antiproliferative effect of a Rho-kinase inhibitor. We suggest a novel use for Rho-kinase inhibitors in the treatment of BPH as a single agent with dual action.

BAY41-2272, a novel nitric oxide independent soluble guanylate cyclase activator, relaxes human and rabbit corpus cavernosum in vitro.

PURPOSE: In cavernous smooth muscle nitric oxide (NO) activates soluble guanylate cyclase, which catalyzes the synthesis of cyclic guanosine 3',5'-monophosphate, leading to smooth muscle relaxation, increased blood flow and penile erection. The pyrazolopyridine derivative BAY41-2272 (5-cyclopropyl-2-[1-(2-fluoro-benzyl)-1H-pyrazolo[3,4-b]pyridine-3-yl]pyrimidin-4ylamine) was identified and found to stimulate soluble guanylate cyclase in a NO independent manner. We investigated the effect of BAY41-2272 on human and rabbit corpus cavernosum. MATERIALS AND METHODS: We investigated the effect of BAY41-2272 on the tone and nitrergic relaxation responses of human and rabbit cavernous strips in the absence and presence of the soluble guanylate cyclase inhibitor ODQ (1H-[1,2,4]oxadiazolo[4-3a]quinoxalin-1-one) or the NO synthase inhibitor L-NAME (N-nitro-L-arginine-methyl ester HCl). The potency of BAY41-2272 was compared to that of another soluble guanylate cyclase activator YC-1, and the NO releasing compound spermine NONOate (N-2-aminoethyl-N-2-hydroxy-2-nitrosohydroazino-1,2-ethylenediamine). RESULTS: BAY41-2272 resulted in concentration dependent relaxation of human and rabbit cavernosum (mean EC50 +/- SEM 489.1 +/- 22.5 and 406.3 +/- 21.5 nM., respectively). The compound was 32 times more potent than YC-1 and twice as potent as spermine-NONOate. ODQ decreased the potency of BAY41-2272, such that in the presence of 30 microM. ODQ the EC50 of BAY41-2272 induced relaxation was 1,407.3 +/- 158.0 and 1,902.7 +/- 11.0 nM. in human and rabbit tissues, respectively. L-NAME also inhibited relaxations elicited by BAY41-2272 in rabbit tissue. In the presence of 500 microM. L-NAME the EC50 of BAY41-2272 induced responses was 836.7 +/- 46.7 nM. BAY41-2272 at subthreshold concentrations of 30 to 50 nM. potentiated nitrergic responses. Moreover, the inhibition of nitrergic responses by L-NAME was reversed by 0.3 to 3 microM. BAY41-2272. CONCLUSIONS: We report that a nonNO based soluble guanylate cyclase activator relaxes human and rabbit corpus cavernosum, and potentiates nitrergic responses.