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Pharmacology: Pharmacodynamics: Ethinyl estradiol and levonorgestrel are contraceptives that suppress gonadotropins. In combination, it primarily prevents ovulation and induces changes in the endometrium and cervical mucus to decrease the possibility of fertilization and implantation.
Pharmacokinetics: Ethinyl estradiol is rapidly absorbed with peak concentration attained within 2 hours.
Ethinyl estradiol is 97% to 98% bound to plasma albumin. Half-life varies from 6 to 20 hours. It is excreted in bile and urine as conjugates and undergoes some enterohepatic recirculation.
Levonorgestrel reaches peak concentrations between 0.5 to 2 hours, does not undergo a first-followed by conjugation. Terminal half-life of the levonorgestrel is 11 to 45 hours.
