of future osteoporosis. Approximately 1200–1500 mg of elemental calcium per day is
suggested for teenagers. Calcium supplementation alone is not sufficient to reverse the
bone loss of established osteroporosis. Some of the inorganic calcium salts that have
been used clinically include calcium carbonate (8.114), tricalcium phosphate (8.115),
calcium citrate (8.116), and calcium gluconate (8.117).
Selective Estrogen Receptor Modulators (SERMs). Antiestrogen compounds such
as tamoxifen (8.118) and raloxifene (8.119) exhibit agonist activity in some tissues
(e.g., bone) and antagonist activity in other tissues (e.g., breast, uterus). Since osteoporosis
is more prominent in post-menopausal women, possibly secondary to a failure of estrogen-
mediatedosteoclast inhibition, SERMs may play a role in the treatment of osteoporo-
sis. Raloxifene has shown some positive results in clinical trials. Alternatively,estrogen
replacement therapy(ERT) with estrogen analogs may be pursued. Such therapies have
ENDOGENOUS MACROMOLECULES 537