Pregnyl is the brand name of Organon's Human Chronic Gonadotropin, a fertility drug used during PCT to bring back testosterone production to baseline. It comes in various concentrations from 250ius all the way up to 10,000ius.
Similarly to HGH, it needs to be mixed with bacteriostatic water and injected subcutaneously witha small pin. I have found that doses of 500ius are the most beneficial- possibly every few weeks during a cycle andonce a day or eod for 2-4 weeks inconjuction with 20mg nolvadex daily for PCT.
Remember, that some drugs such as Deca-Durabolin, are long acting and completely shut down testosterone production (a single shot of deca will do this!) so PCT should start 3 weeks after the last deca shot, or even longer based on the dosage!