Oral contraceptive formulations pharmacokinetics and molecular data

Pharmacokinetics
Absorption Distribution Metabolism Excretion

Absorption
Norgestimate (NGM) and ethinyl estradiol (EE) are rapidly absorbed following oral administration. Norgestimate is rapidly and completely metabolized by firstpass (intestinal and/or hepatic) mechanisms to norelgestromin (NGMN) and norgestrel (NG), which are the major active metabolites of norgestimate. Return to top

Distribution
Norelgestromin and norgestrel are highly bound (>97%) to serum proteins. Norelgestromin is bound to albumin and not to SHBG, while norgestrel is bound primarily to SHBG. Ethinyl estradiol is extensively bound (> 97%) to serum albumin and induces an increase in the serum concentrations of SHBG. Return to top

Metabolism
Norgestimate is extensively metabolized by first-pass mechanisms in the gastrointestinal tract and/or liver. Norgestimate’s primary active metabolite is norelgestromin. Subsequent hepatic metabolism of norelgestromin occurs and metabolites include norgestrel, which is also active and various hydroxylated and conjugated metabolites. Ethinyl estradiol is also metabolized to various hydroxylated products and their glucuronide and sulfate conjugates. Return to top

Excretion
The metabolites of norelgestromin and ethinyl estradiol are eliminated by renal and fecal pathways. Following administration of 14C-norgestimate, 47% (45-49%) and 37% (16-49%) of the administered radioactivity was eliminated in the urine and feces, respectively. Unchanged norgestimate was not detected in the urine. In addition to 17-deacetyl norgestimate, a number of metabolites of norgestimate have been identified in human urine following administration of radiolabeled norgestimate. These include 18, 19-Dinor-17-pregn-4-en-20-yn-3-one,17-hydroxy-13-ethyl,(17 )-(-);18,19-Dinor-5 -17- pregnan-20-yn,3 ,17-dihydroxy-13-ethyl,(17 ), various hydroxylated metabolites and conjugates of these metabolites. Return to top