Prolonged erection after injection

Doctor prescribed me mix of papaverine 17.5, chlorpromazin 1.923, atropine 0.23 . One dose is 24ml. The problem that erection with same dose can last from 1.5-2 hours (that what I want) to 3.45 hours (that's very inconvenient). Is 3.45 hours erection dangerous?
Doctor told me to take pseudoephedrine if erection last more than 2 hours and do step exercises, but it doesn't really helps me.
Anybody using some special technics to end erection when you don;t need it?

Lower the amount you are injecting. If you filling your own syringes then slowly drop your dosage till you get to a good duration. Drop a couple units from your dose each time till you find the proper amount. Of courage you should talk with your doctor about this strategy.

FG

I'd reduce doze, but the problem is that sometimes it's fine... I think that there are many other things involved except dose... how old is solution, your physical and mental conditions at specific time etc...

Yes, last time I took even 3 pseudoephedrine pills and still erection lasted about 3 - 3.20 h

I am definitely not an expert as I was only on Trimix for 3 months. I would have 3.5 hour erections and when I talked with my URO, he told me (like others have here) to drop the dosage slowly till you get one that works. I would also take a long bath. Luckily I never hit the four hour mark and did not have to go to the ER. Best of luck!