Mebolazine (INNTooltip International Nonproprietary Name; brand names Dostalon and Roxilon; also known as dimethazine, dymethazine, di(methasterone) azine, or 2α,17α-dimethyl-5α-androstan-17β-ol-3-one azine) is a synthetic, orally active androgen/anabolic steroid (AAS) and a 17α-alkylated derivative of dihydrotestosterone (DHT) which is no longer marketed. It has a unique and unusual chemical structure, being a dimer of methasterone linked at the 3-position of the A-ring by an azine group, and reportedly acts as a prodrug of methasterone.

Since 2008, mebolazine has been used illegally as an ingredient is some dietary supplements, including vitamin B supplements, and in the United States the Food and Drug Administration has taken legal action against such manufacturers.