What is in an A 159 pill? The white & blue specks, elliptical / oval pill with imprint A 159  has been identified as Phentermine Hydrochloride 37.5 mg supplied by Qualitest Pharmaceuticals Inc. Phentermine belongs to the drug classes anorexiants, CNS stimulants. The drug works by stimulating the central nervous system (nerves and brain), […]