If you have received the "Caverject Impulse". It should have included very detailed directions. The Caverject Kit is a preloaded syringe that has the alprostadil already inside the specially constructed syringe. With that kit you follow the directions and twist the kit which puts the fluid and powder together. You then gently turn the kit to mix it together. Most doctors start you with just a 5 mcg (five microgram) injection. The kit contains 20 mcg and you control the amount by turning until the correct number is in the window. You might need 10 or 20 mcg to really do the job.
If you do not have the KIT, but an injection bottle and regular diabetic syringes, then you still would probably start with 5 mcg.