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Effects of norethandrolone on the transport and peripheral metabolism of thyroxine in patients lacking thyroxine-binding globulin. Observations on the physiological role of thyroxine-binding prealbumin.

Studies of the effect of norethandrolone on the transport and peripheral metabolism of thyroxine were carried out in four patients lacking thyroxine-binding globulin. Before norethandrolone administration, values for serum protein-bound iodine (PBI) were decreased (1.8 +/-0.5 mug/100 ml) and the proportion of free thyroxine increased (0.036 +/-0.008%). As a result, values for the absolute concentration of free thyroxine iodine were at the lower end of the normal range (0.63 +/-0.12 mmug/100 ml). During the control thyroxine-turnover study, the thyroxine distribution space was strikingly increased (18.2 +/-7.9 liters) and the fractional rate of thyroxine turnover moderately increased (17.1 +/-11.3%/day), as compared to the expected mean values for normal subjects. Therefore, calculated values for the daily rate of thyroxine clearance were increased even more, ranging between 255 and 500% of normal values. However, owing to the low PBI in these patients, the daily disposal of thyroxine iodine was similar to that expected in normals on the basis of age and weight. During the administration of norethandrolone, the thyroxine-binding capacity of the thyroxine-binding prealbumin increased strikingly in all patients, values averaging 162% of those found during the control period. This increase was associated with a highly significant increase in PBI (133% of control values) and a small but significant decrease in the proportion of free thyroxine, resulting in no significant change in the absolute concentration of free thyroxine iodine. In all four patients, administration of norethandrolone was associated with a pronounced decrease in the thyroxine distribution space to values which averaged 69% of those found during the control period. Values for the fractional rate of thyroxine turnover increased slightly. As a result, thyroxine-clearance rate decreased in all patients. Owing to the reciprocal changes in clearance rate and PBI, no significant change in total daily thyroxine disposal was observed. The present studies reveal that when the thyroxine-binding prealbumin is increased in patients lacking thyroxine-binding globulin, several indices of peripheral thyroxine transport and metabolism are altered. However, these changes were small, even in the absence of thyroxine-binding globulin. It is suggested, therefore, that the effect of changes in thyroxine-binding prealbumin would be even smaller in individuals in whom thyroxine-binding globulin is present.

Adult↗

Norethandrolone produces temporary loss of the ability to escape from salt-retaining steroids.

Patients with diseases characterized by salt retention manifest a loss of the normal ability of healthy persons to escape from repeat injections of aldosterone or other salt-retaining steroids. This phenomenon may be a clue to the pathophysiological mechanisms of salt retention. Administration of norethandrolone to a subject who had demonstrated the ability to escape from the salt-retaining effect of corticosteroid administration temporarily and reversibly deleted his ability to escape. Thus norethandrolone administration provides the basis for a model system for exploring the mechanisms of escape (and therefore of salt retention).

Body Weight↗

17alpha-ethyl-5beta-estrane-3alpha, 17beta-diol, a biological marker for the abuse of norethandrolone and ethylestrenol in slaughter cattle.

The metabolism of the illegal growth promoter ethylestrenol (EES) was evaluated in bovine liver cells and subcellular fractions of bovine liver preparations. Incubations with bovine microsomal preparations revealed that EES is extensively biotransformed into norethandrolone (NE), another illegal growth promoter. Furthermore, incubations of monolayer cultures of hepatocytes with NE indicated that NE itself is rapidly reduced to 17alpha-ethyl-5beta-estrane-3alpha, 17beta-diol (EED). In vivo tests confirmed that, after administration of either EES or NE, EED is excreted as a major metabolite. Therefore, it was concluded that, both in urine and faeces samples, EED can be used as a biological marker for the illegal use of EES and/or NE. Moreover, by monitoring EED in urine or faeces samples, the detection period after NE administration is significantly prolonged. These findings were further confirmed by three cases of norethandrolone abuse in a routine screening program for forbidden growth promoters.

Animal Husbandry↗

The metabolism of norethandrolone in the horse: characterization of 16-, 20- and 21-oxygenated metabolites by gas chromatography/mass spectrometry.

After oral administration to a thoroughbred gelding, the anabolic steroid norethandrolone was converted into a complex mixture of oxygenated metabolites. These metabolites were extracted from the urine, deconjugated by methanolysis and converted to their O-methyloxime trimethylsilyl derivatives. Gas chromatographic/mass spectrometric analysis indicated the major metabolites to be 19-norpregnane-3,16,17-triols, 19-norpregnane-3,17,20-triols and 3,17-dihydroxy-19-norpregnan-21-oic acids. Some minor metabolites were also detected.

Animals↗

Determination of fluoxymesterone, norethandrolone, prednisolone, and prednisone in tablets by differential pulse polarography.

A differential pulse polarographic method for the determination of fluoxymesterone, norethandrolone, prednisolone, and prednisone in tablets is described. This method is more sensitive than dc polarography, and the measurement of diffusion current is greatly simplified. Sørensen phosphate buffer, pH 5.6, was used as the supporting electrolyte. No apparent interference was observed from tablet excipients; the method is rapid, simple, and relatively precise.

Fluoxymesterone↗

The effect of norethandrolone on organic ion transport by rat renal cortical slices.

Norethandrolone (NE) and other androgenic steroids have been shown to be renotropic in various species and have also been reported to have salutary effects in patients with diminished renal function. Renal cortical slices prepared from rats pretreated with NE showed an increased capability to concentrate p-aminohippuric acid (PAH). Pretreatment with NE failed to stimulate the transport of the organic base tetraethylammonium and the organic acid benzylpenicillin. Stimulation of PAH transport was observed after eight daily subcutaneous injections of NE. No stimulation was observed with shorter pretreatment intervals. When NE was given subcutaneously for 14 days at doses of 2.6 or 20 mg kg-1 day-1, significant stimulation of PAH transport was seen at all three dose levels but no dose-effect relationship was apparent. Stimulation of PAH transport was seen in female rats as well as castrated and intact males. In addition to its general anabolic properties, NE induces the synthesis of hepatic microsomal drug-metabolizing enzymes. For comparative purposes, therefore, the effect of pregnenolone-16 alpha-carbonitrile (PCN) was also investigated. This agent is a potent inducer of drug metabolism but is neither anabolic nor renotropic. When rats were pretreated with an inducing dose of PCN (75 mg kg-1 day-1 for 3 days), there was no significant stimulation of PAH transport. It would seem, then, that the stimulatory effect of NE on PAH transport is more closely associated with its generalized anabolic effect than with its ability to induce hepatic microsomal enzymes.

Aminohippuric Acids↗

[GC-MS analysis of norethandrolone and its metabolites in man].

Steroids in human urine were adsorbed on a macroporous XAD-2 resin, eluted with methanol, hydrolyzed with glucuronidase, extracted and concentrated for TMS derivatization and then analyzed with GC-MS. Norethandrolone (N) and its 9 metabolites were detected in urine samples 9-35 h after oral administration. Met-2 and Met-7 could be detected even in 84 h urine sample. The structures of 7 metabolites were elucidated and the variations of their concentration in urine were determined. The specific metabolites and characteristic ions for screening N positive urine were chosen. This method is sensitive enough; the detection limit of N was 10 ng per ml urine, i.e. 10 ppb.

Gas Chromatography-Mass Spectrometry↗

Evidence for microfilament involvement in norethandrolone-induced intrahepatic cholestasis.

An experimental study of norethandrolone (NED)-induced intrahepatic cholestasis was made. NED was infused via a portal vein catheter into rat liver in vivo, and measurements were made of bile flow. Liver specimens were taken at intervals for light microscopy and for transmission and scanning electron microscopy. Bile-canalicular-rich membrane fractions were prepared. The effects of NED were also examined in isolated hepatocytes in suspension culture. NED infusion induced total cholestasis by 3 hours. Canalicular alterations commonly associated with cholestasis were found in in vivo infused liver and in isolated hepatocytes. Pericanalicular microfilament changes were also noted in both, with loss of filament structure and replacement by a granular zone. In isolated canalicular membrane fractions prepared from NED-treated animals, the normal investment of pericanalicular filaments was no longer present. Loss of the bile canalicular ruthenium red surface coat was also noted. In view of the identical findings in isolated hepatocytes and in in vivo liver, obstruction and mechanical factors can be excluded as possible causes. The results raise the possibility that the mechanism of NED-induced cholestasis may be related to disaggregation and/or detachment of microfilaments from the canalicular membranes.

Animals↗