Any compound (not being Trilostane) which is structurally derived from 17-hydroxyandrostan-3-one (4-dihydrotestosterone) or from 17-hydroxyestren-3-one (19-nortestosterone) by modification in any of the following ways: (i) by further substitution at position 17 by an oxygen, methyl or ethyl group; (ii) by substitution to any extent at one or more of positions 1, 2, 4, 6, 7, 9, 11 or 16, but at no other position; (iii) by unsaturation in the carbocyclic ring system to any extent, provided that there are no more than two ethylenic bonds in any one carbocyclic ring; (iv) by fusion of ring A with a heterocyclic system; (v) by substitution at position 3 by an OH group.