Pharmacologic and pharmacokinetic characteristics of norgestimate and its metabolites

Article Abstract:

Oral contraceptives contain derivatives of two female reproductive steroid hormones, estrogen and progesterone. Norgestimate is a progesterone derivative which has been used in contraceptive formulations. Because metabolites of steroids such as norgestimate often provide a significant portion of the total biologic activity, the metabolism, activity, and pharmacokinetics (tissue handling over time) of norgestimate were evaluated. Three metabolites were identified which might contribute to the total drug response, and these were 17-deacetyl norgestimate, 3-keto norgestimate, and levonorgestrel. Each of these evidenced progestational activity in rabbits, but only 17-deacetyl norgestimate was similar to norgestimate itself in lacking androgenic (male steroid hormone) activity. Biological evaluation of norgestimate and levonorgestrel confirmed these observations. Pharmacokinetic studies indicated that norgestimate is rapidly and largely converted to its 17-deacetylated metabolite, and this product likely contributes significantly to the total contraceptive effect resulting from treatment with norgestimate. Evaluation of steroid metabolism is difficult, but more study of the contribution of metabolites to the effects of norgestimate is needed. (Consumer Summary produced by Reliance Medical Information, Inc.)

Progestational hormones, Synthetic, Progestational agents

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Lumbar vertebral density and mechanical properties in aged ovariectomized rats treated with estrogen and norethindrone or norgestimate

Article Abstract:

A combination hormone replacement therapy involving estrogen and progestin may improve bone density better than estrogen therapy alone in an aged rat model. Researchers studied the effects of estrogen by itself, estrogen with norethindrone, or estrogen with norgestimate on 80 rats whose ovaries had been removed. The use of continuously administered estrogen with an interrupted schedule of progestin (norethindrone or norgestimate) administration improved the bone density of lumbar vertebra. The combination hormone replacement therapy did not cause bones to become less brittle, stronger, or less prone to fracture. The application of these findings to menopausal women is being analyzed in large clinical studies.

Health aspects, Models, Bones, Bone density, Estrogen, Estrogens, Progestational hormones

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A novel intermittent regimen of norgestimate to preserve the beneficial effects of 17beta-estradiol on lipid and lipoprotein profiles

Article Abstract:

Taking norgestimate for 3 days and then stopping for 3 days preserves the beneficial effects that 17beta-estradiol has on blood lipids. However, in a study of 236 women, this was only true for 30 or 90 microgram doses, not 180 microgram doses.

Physiological aspects, Dosage and administration, Norgestimate, Blood lipids

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