Mastabol is a synthetic derivative of dihydrotestosterone, displaying a potent androgenic effect that is responsible for increases in muscle density and hardness and a moderate anabolic effect that creates a positive nitrogen balance in humans and promotes protein synthesis. Since it is a derivative of dihydrotestosterone, dromastanolone does not aromatize at any dosage and thus it cannot be converted into estrogen. Therefore, estrogen-related water retention is eliminated. Mastabol 100 is relatively fast-actiing and fast-clearing because of the attachment of the propionate ester to the base molecule.

Presentation:
Each 10 ml multidose vial contains 100 mg per ml (formerly 50 mg per ml). Beginning in August, 2005, new flip-off tops are white coloured and have Mastabol stamped on them. Older vials have a white coloured generic flip-off top.