The latest advance in the 30-year evolution of oral contraceptives (OCs) is the development of three new progestogens: desogestrel, norgestimate, and gestodene. These three new agents are derivatives of levonorgestrel, a gonane hormone, and have been used to develop pills that provide effective pregnancy prevention at lower doses than oral contraceptives using the older steroids. Desogestrel is a prohormone that must first be metabolized into its biologically active form. Norgestimate is already active, but it will be metabolized in part to levonorgestrel. Gestodene is biologically active in its native form. Among the improvements in metabolic parameters seen with this new generation of progestogens are a lack of impact on blood pressure, a balanced effect on coagulation, and a reduced impact on carbohydrate metabolism compared with earlier, higher-dose formulations. The new pills also seem to produce no negative effects on lipid and lipoprotein biosynthesis, and perhaps even improve the ratio of low-density lipoprotein to high-density lipoprotein.
Cycle control with all three progestogens is improved, with much lower incidence of intermenstrual bleeding (IMB). Efficacy is as good as with other OCs. Another benefit of the new low-dose progestogens, however, is the low incidence of minor side effects observed in women using these contraceptives. Low incidences of weight gain, headache, and nausea were reported, and the dropout rate because of side effects was low in both international and US trials. Serious side effects are rarely seen with pills containing the new progestogens.
The development of gestodene, desogestrel, and norgestimate will provide expanded OC choices for women, with the promise of efficacy equal to and safety and cycle control improved over previous higher-dose OCs.
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