Minocycline (INN) is a broad-spectrum tetracycline antibiotic, and has a broader spectrum than the other members of the group. It is a bacteriostatic antibiotic, classified as a long-acting type. As a result of its long half-life it generally has serum levels 2–4 times that of the simple water-soluble tetracyclines (150 mg giving 16 times the activity levels compared with 250 mg of tetracycline at 24–48 hours).