Going to share the first time experience I had last night. Maybe it will help someone else.
WHOA this stuff is no joke and not to be played with.
For reference, my mixture is the standard 5ml vial from Empower as follows (measurements are PER VIAL, not per ml):
150mg papaverine
5mg phentolamine
50mcg prostaglandin E1
My doctor said do 3 to 5 units.
Pharmacy said do 5 to 20 units.
Nelson and others recommended 10-12 units.
Other forums have guys doing 30 units.
Knowing that I am usually a hyper-responder to any drug or compound, I should have done less than the lowest recommended dose but instead I went with 5 units which was the lowest dose the pharmacy recommended and within what the doctor recommended.
I used a 5/16" 30 gauge needle. Hardly felt it at all. No pain.
15 minutes later and I had a slab of granite in my shorts. This was 830pm. Had sex for an hour or so. 930pm no change at all. 1030pm no change at all. 1130pm no change at all. 3 hours and still 100% rock hard. Starting to get a little scared. Figured it would be at least somewhat starting to go down by now. I get an ice pack and start freezing the whole area, taking breaks to rub and pull and try to get some blood moving around. 12am no change at all. 3.5 hours and starting to freak out. I waited another 15 minutes and decided fuck it, emergency room here I come. I live literally across the street from a big hospital so I got dressed, walked out the door and noticed the slightest change. I was maybe at 90% now. So I decided to pace around and keep my legs moving. By 130am (5 hours gone by) I was maybe at 40-50% so I reasoned at least blood was circulating and flowing back out, albeit slowly. By 230am I still wasn't back to normal, but at maybe 20% erect I was calm enough to go to sleep. Woke up with my usual crazy morning boner and for a second I really freaked the fuck out thinking it had never gone away, but by the time I got up and pee'd and walked to the kitchen it was mostly gone like any normal morning.
I would urge anyone doing this for the first time to start with 2 units. I don't care what your doctor says or what you hear on the internet. You can always slowly increase the dose next time if you don't get the desired effect. Once you do too much you're really screwed, and you just don't know what too much is since it's so different for everyone.