(a) A n d rogen s
(b) A nabolic steroid s
F I G U R E 3 4 - 3
Synthetic androgens, anabolic steroids, and an antiandrogen.
fluoxymesterone (Figure 34-3), which have protected 17-
hydroxyl residues, are potent androgenic drugs. Substitu-
tions in the A ring while protecting the 17-hydroxyl group
decrease the androgenic potency of the steroid while en-
hancing the anabolic potency.
Pharmacological Inhibition of Spermatogenesis or
Fertility (Male Contraception)
Attempts to devise a male contraceptive (antifertility) have
involved the testing of a number of chemicals for their
ability to interfere with spermatogenesis or spermatozoa
viability. In order to be effective, a contraceptive would
have to produce azoospermia (complete absence of sper-
matozoa in ejaculate) because pregnancies have resulted
with sperm counts as low as 1 x 10
per mL or less.
Synthetic derivatives of testosterone with
long biological half-lives have been used to create
azoospermia in most subjects after 42 weekly treatments.
The mechanism involved is the suppression of both LH
and FSH release by way of hypothalamic GnRFl inhi-
bition. Although exogenous testosterone treatment main-
tains the androgen supply to most tissues, the seminifer-
ous tubule compartment is androgen-deficient because the
Leydig cells are not functional in this LFI-deficient con-
dition. Thus, the requirement for high local concentration