Going on from the non testosterone and nitric oxide related interventions this site looks at the Spinal role of processing an erection. Again this is not the whole story, as we know for some men testosterone is at least part of the problem. But it is interesting that drugs are being developed which attempt to stimulate dopamine receptor agonists with some success. http://www.nature.com/ijir/journal/v15/n2s/full/3900989a.html#Spinal-processing-of-the-erectile-response
It shows that when you look in the right place and work on the correct pathways you get promising results. This is the kind of work I imagine can be improved upon to the benefit of MAN
" It is now widely understood that central disinhibition plays a crucial role in the induction of erectile responses and this has led to the development of the central initiator, apomorphine SL (Ixense™) [apo SL]. Apo SL acts in the paraventricular nucleus of the hypothalamus as a dopamine receptor agonist. It works as a proerectile conditioner at this level to increase the responses of the erectile pathway following appropriate sexual stimulation. This unique central mode of action of apo SL has thus proved efficacious in approximately 70% of ED patients although persistence may be required to produce a robust effect for the maximum number of patients
"The clinical efficacy of apo SL has been clearly demonstrated during double-blind crossover clinical trials in over 5000 men with varying degrees of ED from mild to severe. These studies have demonstrated a two-fold increase in the percentage of erections firm enough for intercourse compared to placebo and that apo SL is particularly effective in men with mild-to-moderate ED. The rapid onset of action of apo SL, occurring within 20 min for most patients could help men with ED improve spontaneity in their sexual relationships. The effectiveness of apo SL increases with sequential dosing for patients who sustain the treatment beyond four doses. This treatment regimen offers patients the opportunity of achieving satisfactory sexual performance."
I suspect it is not surprising that interventions sometimes fail with HRT when the problem might have lain all along with the dopamine and possibly acetylcholine circuitry that effects an erection. Mind you all the various hormonal and neurological systems must no doubt work seamlessly for an erection to occur. Happy as I am that these new interventions finally look beyond testosterone and nitric oxide, more diagnostic tools seem required to give men better feedback to indicate whether the problem lies with neurotransmitters or hormones. And even then I think we still require an understanding of why these circuits fail, to allow the treatment of male sexual dysfunction to become a mature science. For me treating symptoms will never be enough. After all prevention will always be better than cure.
I am particularly impressed by the speed at which the apo SL takes effect, which again suggests to me when western medical science gets it's act together like it has for so many other ailments we will get a powerful treatment for ED. Of course it isn't a universally successful treatment which might again suggest that not all ED is the same- a possibility that it Nitric Oxide or compromised T levels might be the other factors? I hate it when they say persistence may be required- it makes me think that they are merely suggesting that more dosages will eventually gain traction with the problem. To me that might be flogging the same dead horse that some men have been asked to flog when dealing with HRT. It might just be the case that they don't understand the full extent of the problem and that a more rounded therapeutic intervention on several fronts might totally restore function- testosterone, nitric oxide and dopamine for example?