What is M522 7.5 325 Pill? The white oval pill with imprint M522  7.5 325 has been identified as Acetaminophen and Oxycodone Hydrochloride 325 mg / 7.5 mg supplied by Mallinckrodt Pharmaceuticals. Oxycodone is an opioid pain medication, sometimes called a narcotic. Acetaminophen is a less potent pain reliever that increases the effects of oxycodone. […]