Norgestimate: a clinical overview of a new progestin

Abstract

The efficacy and safety of a new monophasic oral contraceptive, norgestimate/ethinyl estradiol, containing the third-generation progestin, norgestimate (250 micrograms), and ethinyl estradiol (35 micrograms), are reviewed. Norgestimate/ethinyl estradiol demonstrates excellent contraceptive efficacy, with a Pearl index of 0.25. Cycle control is reliable, with a low incidence of breakthrough bleeding and spotting. Because of the minimal androgenicity of norgestimate, norgestimate/ethinyl estradiol has a low impact on carbohydrate and lipid metabolism. It neither reduces the vasodilatory and antiaggregatory prostacyclin nor increases its endogenous antagonist, thromboxane. Norgestimate/ethinyl estradiol has no significant effect on blood coagulation factors. All these characteristics suggest that norgestimate/ethinyl estradiol may be associated with a lower risk of cardiovascular disease than other oral contraceptives currently available. Epidemiologic data, however, are not available, and physicians should be reluctant to prescribe it or any oral contraceptive to patients who have a history of vascular or thrombotic disorders.

PIP: Researchers have found that oral contraceptives (OCs) change carbohydrate and lipoprotein metabolism and these changes are like those linked with increased risk of cardiovascular (CV) disease, especially myocardial infarction and stroke. Since CV disease is the major cause of death in US women, it is important that OCs not induce changes in carbohydrate and lipoprotein metabolism. A new progestin, norgestimate, has an advantage over other progestins in that it tends not to induce male traits. This is beneficial because androgenicity is related to atherosclerosis which increases the risk of myocardial infarction. Further studies show that the new combined OC (250 mcg norgestimate/35 mcg ethinyl estradiol) does not influence serum glucose tolerance levels. It also does not affect the physiologic regulating system of prostacyclin, the inhibitor of platelet aggregation, by high density lipoprotein (HDL). In addition, it increases prostacyclin metabolites and HDL which may indeed decrease the risk of occlusive thrombotic vascular diseases. Moreover a study in Germany demonstrates that it causes no changes in fibrinopeptide A,m the anticoagulation factors antithrombin III and protein C, or coagulation promoting factors fibrinogen, factor VII, and the components of VIII. In women, it is absorbed well and metabolized extensively before the body eliminates it. Moreover this new combined OC has an overall Pearl index of 0.25. Studies to data indicate that norgestimate/ethinyl estradiol may be more advantageous than other OC formulations. Yet only long term epidemiologic studies can determine if it can indeed decrease the risk of CV diseases linked with older OCs.