Well, as a matter of fact,......
Last night I wanted to make sure that I would be able to successfully complete the full act, so I used .25cc/ml of trimix, rather than my usual .15cc/ml. I had a full useful erection up to the 3 1/2 hr. mark, and it was still at least 1/2 erect at 4 hrs. I was told by my doc and have read several places that if the erection has subsided close to 1/2 way at the 4 hour mark, then it isn't a big danger of serious injury to the organ. I don't sweat it as much anymore if I hit the 4 hr. mark and it has subsided that much. By the 5 hrs it had subsided back to 1/4 erect and finished the job sometime after I went to sleep.
Now then, I think I read somewhere you used bimix, and I have been talking about
As you probably know, trimix will result-usually- in a harder erection using less drug. So the dangers of priaprisms are somewhat greater with trimix. I do use bimix, also, to sorta rotate things. I normally have to use .30 cc/ml of bimix to achieve something near the same result that I do with trimix. I will admit I have more failures with bimix, failures being described as not firm enough for satisfying intercourse. Of course, it's each guys idea as to what is satisfying. To me, I want to be firm enough to easily penetrate and stay inside. The bimix erection allows for penetration, but makes it more difficult to stay inside, as it is a 'softer' kind.
As the guys have said, like everything PCa wise, it is very much an individual thing as to how long and how much we use of the drug. I notice you say you are using Viagra with the bimix. That's something I won't do, myself, as they really are acting against each other. Viagra acts to increase blood flow to the area, including the penis, and bimix acts to close down the valves inside the penis- to hold the blood in. Just how it affects only the ones that keep the blood in the penis is beyond my knowledge, but using the pills and the drugs seem counter-intuitive to me , at least.
Back to the question, I have had close to 4 hour erection, both with trimix and bimix, but only one time actually felt any danger. That was the first time, with a much larger than needed dose of Caverject. Since then, I can approach the 4 hr. mark often, the only result is 3 hours of erection that I can't use, and a sense of aching until it goes down finally. It sounds as if you may be approaching a successful system for it. If you want my opinion, I'd not do the Viagra with the drug. I'd experiment a little more, changing the amount of bimix you use slightly, maybe a half a point at a time. Sounds like you are close, but need to work on the 'fear factor' some by having a few good experiences. Some things to consider- the age of the mix, whether it has been refrigerated all the time you had it, your injection technique, maybe try the pre-plump method, with less drug and work your way up that way. People seem to have better control of it and have more consistent results if you can eliminate some variable, which this method does, by making sure the same dose is kept in the penis to be adsorbed every time. One thing I don't think has been asked or answered. What is the ratio or strength of the papaverine and phentolamine in the bimix?
I'm sure others will weigh in with their ideas. Hope this helps.