A pharm animal is an individual who likes to abuse pharmaceuticals. These can include benzos (Xanax, Valium), painkillers (Percocet, Vicodin, OxyContin), hypnotics (Ambien, Lunesta), amphetamines (Adderall, Vyvanse), etc.
Guy #1: Dude, did you just see that chick blow a line of adderall?
Guy #2: Yeah dude, I know her. Total pharm animal.