Serum protein binding characteristics of cyproterone acetate, gestodene, levonorgestrel and norethisterone in rat, rabbit, dog, monkey and man

Protein binding characteristics including percentage of total binding, total binding capacity (pmol/mg protein), degree of specific binding, competition with dihydrotestosterone (DHT) and estradiol (E2) binding sites and dissociation constants (Kd) of low and high affinity binding sites were investigated for the progestins cyproterone acetate (CPA), gestodene (G), norethisterone (NET) and levonorgestrel (LN) in serum or plasma pools from man and four laboratory animal species (rat, rabbit, dog and monkey). Serum pools from animals were constructed from samples obtained either prior to or 1 day after pretreatment with ethinyl estradiol (EE2) (5 micrograms/kg/day for 7 days). Human plasma pools differed by SHBG levels (normal/induced). All serum pools were characterized by protein content and distribution. Equilibrium dialysis or dextran-coated charcoal (DCC) methods were used to separate bound and free steroids labelled with tritium. All progestins were highly (greater than 80%) bound to proteins in all undiluted samples. Total binding capacity was highest in rat and lowest in monkey. Human plasma showed a capacity of 1.5-2.1 microgram steroid/ml. In man, monkey and rabbit LN and G were specifically bound to the same degree as DHT, whereas NET binding was 50% lower. Specific binding of CPA to dog serum was 2-3 times higher than for other steroids. Two (high and low affinity) binding sites were found for LN, G and NET in man, monkey and rabbit and in dog for LN. Kd values for high affinity binding ranged from 3.5 (G in man) to 23 (NET in man) x 10(-9)M. Kd values of low affinity binding varied from 0.5 (CPA in dog) to 4 (NET in man) x 10(-6)M. E2 and DHT competition experiments confirmed the concept of SHBG as a carrier protein of 19-nor-progestins and DHT and its occurrence in man, monkey and rabbit. A sex hormone binding protein (SBP) in the dog seems to be responsible for the relatively high specific binding of CPA. SHBG is inducible by means of EE2 in man and monkey, but not in rabbit. EE2 may induce SBP in the dog. Comparison of in vitro Kds (high affinity binding) and in vivo metabolic clearance rates showed the same rankings for LN, G and NET in man, monkey and rabbit.     

Isolation and partial synthesis of a new metabolite of medroxyrogesterone acetate.

3 alpha-Hydroxy-17-acetoxy-6 alpha-methyl-5 beta-pregnan-20-one (IIIa) has been isolated from urine of patients receiving medroxyprogesterone acetate (MPA). It was characterized by partial synthesis from MPA by catalytic reduction with palladium-charcoal to 17-acetoxy-6 alpha-methyl-5 beta-pregnan-3,20-dione (IV) and reduction of the latter with sodium borohydride. The isolation of 6 beta, 17,21-trihydroxy-6 alpha-methyl-pregn-4-ene-3,20-dione (IIc) is reported for the first time. The 17- and 21-monoacetates of this compound have been isolated and characterized earlier by other investigators. 7 alpha-3H-Medroxyprogesterone acetate was administered to 4 subjects by intravenous and intramuscular injections and by mouth. The ring A saturated metabolite IIIa was excreted in 0.1% to 4.0% of the administered dose; the highest excretion was after the intravenous dose and lowest after oral ingestion. 6 beta, 17,21-Trihydroxy-6 alpha-methylpregn-4-ene-3,20-dione (IIc) and its 17- and 21-monoacetates were excreted in about 5% of the doses in all subjects. No increase in 6 beta-hydroxylation was observed in the patient treated with o,p'-DDD,2,2-bis(2-chlorophenyl, 4'-chlorophenyl)-l,1-dichloroethane.     

Effect of cyproterone acetate on prolactin secretion in the female rhesus monkey

Summary Adult female rhesus monkeys were given cyproterone acetate orally in doses of 0.04, 0.4, 4 and 40mg per kg per day for 12 weeks. Its effects were assessed on serum prolactin (PRL) concentration, the morphology of the PRL cells, and the development of the mammary glands. Serum PRL was relatively unchanged in the control animals from the fourth through the twelfth weeks of the study. In contrast, PRL was significantly elevated in each group of drug-treated animals during the same time periods. There was no development of the mammary glands nor was there any evidence of milk secretion in the control animals; however, in the monkeys given cyproterone acetate the mammary glands had extensive lobuloalveolar growth and milk-like secretion that could be expressed as early as the fourth or fifth week of the study. By immunocytochemistry and differential light microscopic staining techniques, the PRL cells in the pituitary glands of the experimental animals were found to be more numerous and much larger than those present in the controls. They displayed a well developed Golgi complex and had an abundance of cytoplasmic RNA. These data suggest that PRL secretion is markedly enhanced by cyproterone acetate.Supported in part by USPHS Grant AM12583     

Identification of the major urinary metabolite of alprenolol in man, dog and rat

After oral administration of ³H-alprenolol to man, dog and rat, urinary metabolites of the drug have been separated by ion-exchange chromatography on Bio-Rex 70, a carboxylic acrylate resin. The major metabolite has been identified by GC-MS as 4-hydroxyalprenolol. Occurring in the urine largely in a conjugated form, it represents about 40 % of the excreted amount in man and dog and about 30 % in rat. Including alprenolol, which also appears largely as a conjugate, about 80 % of the amount of radioactivity excreted in human urine can be accounted for.     

Isolation and identification of alectrol as (+)-orobanchyl acetate, a germination stimulant for root parasitic plants

Alectrol, a germination stimulant for root parasitic plants, was purified from root exudates of red clover (Trifolium pratense L.) and identified as a strigolactone, (+)-orobanchyl acetate [(3aS,4S,8bS,E)-8,8-dimethyl-3-(((R)-4-methyl-5-oxo-2,5-dihydrofuran-2-yloxy)methylene)-2-oxo-3,3a,4,5,6,7,8,8b-octahydro-2H-indeno[1,2-b]furan-4-yl acetate], by 1D and 2D NMR spectroscopy and ESI- and EI-MS spectrometry. Orobanchyl acetate afforded an [M-42](+) ion in EI-MS and thus had been recognized as an isomer of strigol. Orobanchyl acetate was detected in root exudates of soybean (Glycine max L.) and cowpea (Vigina unguiculata L.) along with orobanchol.     

Methyl diethyldithiocarbamate, a metabolite of disulfiram in man.

Following the oral administration of disulfiram to alcoholic patient volunteers, methyl diethyldithiocarbamate (MeDDC) was noted in blood withdrawn between one and two hours after dosing. This is consistent with previous reports of MeDDC in mice and dogs. It is suggested that MeDDC is an intermediate in the formation of urinary sulfate.     

Isolation and structure elucidation of isoaltenuene,a new metabolite ofAlternaria alternata

Mycotoxin Research - Isoaltenuene, a previously unknownAlternaria metabolite has been isolated from a rice culture ofAlternaria alternata and purified by semipreparative HPLC. The assigned...     

Androgen dynamics in vitro in the human prostate gland. Effect of cyproterone and cyproterone acetate

Hyperplastic and adenocarcinomatous human prostatic tissue was superfused in vitro with radioactively labelled androst-4-ene-3,17-dione, testosterone and 5alpha-dihydrotestosterone (17beta-hydroxy-5alpha-androstan-3-one), with and without addition of the anti-androgens cyproterone and cyproterone acetate. Cyproterone competitively inhibited the entry of the androgens into the majority of the tissues, whereas cyproterone acetate increased this entry. These findings indicated that transport of androstenedione, testosterone and 5alpha-dihydrotestosterone into prostatic tissue is performed by a specific mechanism, possibly involving a carrier situated in the cell membrane. The extent of metabolism of the three androgens was also modified: formation of 5alpha-dihydrotestosterone from testosterone, and of the latter from androstenedione, was decreased by cyproterone and increased by the acetate. Acetate was more effective than cyproterone in decreasing the ;uptake' of the perfused androgens by the tissue; at the same time, it increased the androgen clearance from the tissue. As cyproterone acetate is the more potent of the two anti-androgens, the possibility that these findings in vitro are related to the different anti-androgenic potency exhibited by the two compounds in vivo is discussed. ;Uptake' of the two anti-androgens and the response to their action on androgen dynamics were similar in adenocarcinomatous and hyperplastic glands.     

High-performance liquid chromatographic isolation and fast atom bombardment mass spectrometric identification of Di-N-desethylamiodarone, a new metabolite of amiodarone in the dog

Amiodarone is an antiarrhythmic drug which has received considerable attention in recent years. It has been suggested that the unusual pharmacodynamic characteristics of this drug may be due in part to the influence of active metabolites. Using fast atom bombardment (FAB) mass spectrometry we have identified a new metabolite of amiodarone, the di-N-desethyl analog (DDEA). This metabolite was present in the blood of dogs treated with the parent drug, and showed a greater affinity for myocardium than did the parent drug. The unique features of FAB mass spectrometry over electron impact mass spectrometry was an essential element in facilitating the identification of this new metabolite. Whether or not this metabolite has pharmacologic activity or is responsible for some of the side effects occurring during amiodarone administration is not known.     

The identification of a new metabolite of phencyclidine

A new metabolite of phencyclidine, formed in incubation mixtures of rabbit liver preparations and phencyclidine, has been identified as N-(5-hydroxypentyl)-1-phenylcyclohexylamine (I). This compound could result from the reduction of an aldehyde generated by α-carbon hydroxylation of the piperidine ring of phencyclidine. The identification is based on comparison of gas chromatographic and mass spectral properties of metabolite with synthetic material.     

Isolation and identification of a calicivirus from a dog with diarrhoea

The isolation and the characterisation of a calicivirus strain (213/95) from a dog with diarrhoea are reported. The virus grows only in cell cultures of feline origin (Crandell Feline Kidney Cells), and in neutralisation test the isolate demonstrated a slight antigenic correlation with the reference feline calicivirus strain (FCV-F9).