I believe Bane can make the serum himself, though, indeed he had it made for him during Knightfall. I can't state a specific instance, but I seem to recall that he made it at times.
As for the other question:
"Venom
Venom is a potently addictive strength-enhancing super-steroid. According to JSA Classified #17 (November 2006), Venom is based on the Miraclo formula developed at Bannerman Pharmaceuticals, the drug company formerly owned by Rex Tyler, the original Hourman. The first appearance of the drug was a five-part story arc, Batman: Venom[15], in Legends of the Dark Knight issues 16-20. Batman became addicted to the drug while searching for a way to cope for his imperfections. Later, it resurfaced as the power source for Bane, who used it to overpower and cripple Batman in the Knightfall story arc. A version of it is used by President Lex Luthor in the first "Superman/Batman" story arc."