Progestin metabolism

The naturally occurring estrogens and progestins are not orally active because they are rapidly metaboli-cally inactivated. The major site of estrogen and progestin metabolism is the liver. Both are subject to first-... 

The new progestins are believed to have little, if any, effect on carbohydrate metabolism. Nonsmoking women younger than 35 years with diabetes, but no vascular disease, can safely use CHCs, but diabetic women with vascular disease or diabetes of more than 20 years duration should not use OCs. 

Progestins are nsed for varions menstmal cycle disorders, for functional uterine bleeding of various origins, and as a contraceptive. Progestin therapy is also used to treat endometriosis and endometrial carcinomas. Progesterone is not effective when taken orally due to intensive metabolism, and therefore it is used by either parenteral or transvaginal introduction. 

Rifampin is known to induce the hepatic microsomal enzymes that metabolize various drugs such as acetaminophen, oral anticoagulants, barbiturates, benzodiazepines, beta blockers, chloramphenicol, clofibrate, oral contraceptives, corticosteroids, cyclosporine, disopyramide, estrogens, hydantoins, mexiletine, quinidine, sulfones, sulfonylureas, theophyllines, tocainide, verapamil, digoxin, enalapril, morphine, nifedipine, ondansetron, progestins, protease inhibitors, buspirone, delavirdine, doxycycline, fluoroquinolones, losartan, macrolides, sulfonylureas, tacrolimus, thyroid hormones, TCAs, zolpidem, zidovudine, and ketoconazole. The therapeutic effects of these drugs may be decreased. 

The usual routes of administration and durations of action of the synthetic progestins are listed in Table 40-2. Most of these agents are extensively metabolized to inactive products that are excreted mainly in the urine. 

In the animal body three important groups of hormones are formed by the metabolism of cholesterol the progestins, the sex hormones, and the adrenal cortical hormones 249 Their synthesis occurs principally in mitochondria of the adrenal cortex and the gonads. Steroid hormone synthesis is regulated by hormones, such as corticotropin (ACTH), from the anterior pituitary250 (see Chapter 30) and is also dependent upon the recently discovered steroidogenic acute regulatory protein, which in some way promotes the movement of stored cholesterol into mitochondrial membranes.251 252 Some major pathways of... 

Progesterone is rapidly absorbed after its administration by any route. It has a short half-life in the plasma, since it is almost completely metabolized in one passage through the liver. The glu-curonidated metabolite (pregnanediol glucuronide) is excreted by the kidney. Synthetic progestins are less rapidly metabolized. 

The correct answer = C. Progesterone is synthesized by the testes in males. Progestins decrease HDL and increase LDL. When orally administered, progesterone is largely inactivated by hepatic first-pass metabolism. Weight gain is one of the side effects of progestins. 

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