Glucuronide conjugation estrogens

BZDs biotransformed by hepatic oxidation have relatively long half-lives and usually have active metabolites ( Table 12-10). Those biotransformed by glucuronide conjugation have relatively short half-lives and no active metabolites. Only a few BZDs (e.g., clonazepam) are biotransformed by nitro reduction. Although oxidized BZDs and their metabolites may be more likely to accumulate due to age, liver disease, or concomitant use of estrogens or cimetidine, clinical data substantiating this theory are incomplete. 

Caution should also be exercised when assaying samples from subjects who are receiving oral contraceptives or estrogen replacement therapy because cross-reacting steroids may cause elevated results. Most notably, cross-reactivity with estrone is as high as 10% for some assays, but much lower (<1%) in others. This is likely due to a difference in the specificity of the antibody used for estradiol. Similar effects have been observed for metabolites conjugated at the 3 position, like estrone-3-sulfate and estrone-3-glucuronide. ... 

Estrogens undergo glucuronide and sulfate conjugation to a variety of minor metabolites that are excreted primarily in the urine. 

Pharmacokinetics Most estrogens are well absorbed orally. They tend to be rapidly degraded by the liver during their first pass from the gastrointestinal tract. Metabolites include glucuronide and sulfide conjugates of estradiol, estrone, and estriol. 

Metabolism of the estrogens to their water-soluble glucuronide and sulfate conjugates occurs mainly in the liver. Creation of a reservoir of estrogen occurs as a result of enterohepatic recycling, a process by which estrogens undergo desulfation followed by resulfation. 

---