Effects of an oral contraceptive containing drospirenone on bone turnover and bone mineral density

To compare the effects of a new 21-day combined oral contraceptive containing 30 microg ethinyl/estradiol plus 3 mg drospirenone with a 21-day preparation containing 30 microg ethinyl/estradiol plus 75 microg gestodene on bone turnover and bone mineral density in young fertile women.

A randomized, controlled trial was conducted with healthy fertile women treated with 30 microg ethinyl/estradiol plus 3 mg drospirenone (group A; n = 24), 30 microg ethinyl/estradiol plus 75 microg gestodene (group B; n = 24) and healthy controls (group C, n = 23). At 3, 6, 9, and 12 months of the study, serum and urinary calcium, osteocalcin, urinary pyridinoline, and deoxypyridinoline were measured. At baseline and after 12 months, lumbar bone mineral density was determined by dual-energy X-ray absorptiometry.

In groups A and B, urinary pyridinoline and deoxypyridinoline at 6, 9, and 12 months were significantly reduced in comparison with basal values and group C (P < .05). Pyridinoline and deoxypyridinoline levels were lower in group A than in group B throughout the study, but not significantly. In group A serum calcium levels were significantly increased after 6 months. At 12 months, no significant difference was detected in lumbar bone mineral density values among the 3 groups and in comparison with basal values.

Both combined oral contraceptives exert a similar positive influence on bone turnover and bone-sparing effect in young postadolescent women.