Each GP Mast 100 milliliter contains 100 mg of Drostanolone Propionate. GP Mast 100 is available in a 10ml multi dose vial. GP Mast 100 is used as a replacement of male sex steroids in men who have androgen deficiency, for example as a result of loss of both testes and the treatment of certain rare forms of aplastic anaemia which are or may be responsive to anabolic androgens.