Minocycline hydrochloride is a salt prepared from minocycline, taking advantage of the two basic dimethylamino groups which protonate and readily form a salt from hydrochloric acid solutions. The hydrochloride is the preferred formulation for pharmaceutical applications. Like all tetracyclines, minocycline shows broad spectrum antibacterial and antiprotozoan activity and acts by binding to the 30S and 50S ribosomal sub-units, blocking protein synthesis.