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.(ABSTRACT TRUNCATED AT 250 WORDS)