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PubMed1979

Lynoestrenol.

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Animals↗
PubMed1979

Accumulation of norethindrone and individual metabolites in human plasma during short- and long-term administration of a contraceptive dosage.

Blood levels of free, sulfate, and glucuronide conjugates of norethindrone (NE) and its ring A reduced metabolites 17alpha-ethynyl-5beta-estrane-3alpha, 17beta-diol and 17alpha-ethynyl-5alpha-estrane-3alpha, 17beta-diol were measured in a female volunteer who received six consecutive daily doses of 2.5 mg. of NE and in four female volunteers undergoing chronic treatment with Orthonovum 2 mg. (2 mg. of NE and 0.1 mg. of mestranol [ME]). The blood levels were quantified by gas chromatograph-mass spectrometry. During treatment for 6 days with 2.5 mg. of NE daily, the 3 hour blood levels of NE and the ring A reduced metabolites increased in a stepwise fashion. During long-term treatment the concentrations of NE, NE sulfate, and the conjugates of the ring A reduced metabolites were seen to build up to a peak at approximately the midpoint of the treatment phase of each cycle, and drop to near baseline during the time when no drug was administered. Individuals varied as to their tendency to accumulate the drug and metabolites, and as to the relative proportion of metabolites formed.

Adult↗
PubMed1979

Pharmacokinetics of norethindrone acetate in women.

The plasma half-life, MCR and plasma metabolite levels at various time intervals have been studied in six women after an intravenous injection of 3H-norethindrone acetate. The disappearance curve due to norethindrone acetate showed an initial rapid disappearance of 3H with an average half-life of 7.5 minutes and a subsequent slow disapperance with a half-life of 51.5 hours. Norethindrone acetate was cleared from the plasma with an average MCR of 495 L/day. Norethindrone acetate is rapidly metabolised after an intravenous injection. Norethindrone, the main metabolite, disappears from the plasma with an average half-life of 34.8 hours. Norethindrone maintains a high level compared with norethindrone acetate at all time intervals up to 24 hours and an equilibrium is reached between the two at 24 to 48 hours.

Acetates↗
PubMed1979

Pharmacokinetics of norethindrone in Indian Women.

Pharmacokinetics of norethindrone (NET) was evaluated in eleven women belonging to a low socio-economic group and in five womem belonging to the high socio-economic group after the administration of an oral dose of 0.35 mg NET minipill on an empty stomach. Blood samples were collected at different intervals of time over a period of 24 hours. Plasma NET was estimated by radioimmunoassay. In all women, peak levels of NET occurred within 1-2 hours and a semi-log plot of plasma NET levels showed a biexponential decline. The half-life of plasma NET clearance was relatively shorter in women of low socio-economic group with poor nutritional status as indicated by anthropometric indices, as compared to that in well nourished women of high socio-economic group. There was a significant positive correlation between weight/(height) 2x 100 index on the one hand and t1/2 (beta) on the other in all the women studied, thereby suggesting a role for nutritional status in the metabolic handling of NET.

Absorption↗
PubMed1979

Intravaginal contraception with the synthetic progestin, R2010.

Four women used polysiloxane vaginal rings of core design containing 50 mg of norgestrienone (17 alpha-ethynyl-17 beta-hydroxy-estra-4,9,11,trien-3-one). The treatment was given in three-week cycles, leaving one treatment-free week between the cycles. The patterns of bleeding were registered and plasma norgestrienone (R2010), estradiol, progesterone, and gonadotropins were determined. Altogether twelve cycles were studied. The patterns of bleeding were unsatisfactory; only one subject had regular bleedings, and two of these were preceded by a luteal phase. The mean plasma concentration of norgestrienone (R2010) produced by the rings was 0.9 ng/ml. Ovulation was observed in 25% of cycles studied. Some follicular activity was present in every subject as judged by estradiol peaks. Excluding LH peaks in subjects who ovulated, mild pituitary suppression was achieved by this treatment. The only side-effect complained of was acne in one subject. The ring was regarded as easy to use.

Adult↗
PubMed1979

An investigation of the pharmacokinetics of ethynylestradiol in women using radioimmunoassay.

A radioimmunoassay for ethynylestradiol (EE) which is applicable to plasma samples obtained from women, who have taken a combination type oral contraceptive, has been developed and fully validated. Plasma concentration of EE rise to a peak of 128 pg/ml following the oral administration of 50 microgram EE. Following the intravenous administration of the same dose of EE, plasma concentrations of the steroid declined biexponentially, the two half-lives being 0.83 and 6.75 hours. Comparison of the results of the intravenous and oral administration of the steroid suggested that its oral bioavailability is 42%. Although EE thus has a lower bioavailability than norethindrone, the pharmacokinetics of the two steroids, as reflected by half-lives, plasma clearance and volume of distribution, are very similar. The occurrence of a secondary peak in plasma at around 12 hours after dosing gave strong evidence that EE undergoes enterohepatic circulation in women; an event that may have considerable clinical significance.

Administration, Oral↗
PubMed1979

A comparison of medroxyprogesterone serum concentrations by the oral or intramuscular route in patients with persistent or recurrent endometrial carcinoma.

A randomized study, comparing serum medroxyprogesterone concentrations by the oral and intramuscular routes, was performed on 22 patients with persistent or recurrent endometrial adenocarcinoma by six institutions of the Gynecologic Oncology Group. The oral group (11 patients) received cutaneous Provera (medroxyprogesterone), 50 mg three times a day, and the intramuscular group (11 patients) received 300 mg of Depo-Provera (medroxyprogesterone) weekly for at least 2 months. Serum levels were evaluated at 0, 2, 4, 6, 8, 10, and 12 hours after administration and every day for the first week and weekly thereafter for 8 weeks. The mean serum levels (nanograms per milliliter) of medroxyprogesterone in the oral group were consistently higher than the corresponding mean levels of the intramuscular group. In addition, from the first through eighth weeks, the measurements (medians) for the oral group were statistically higher than those for the intramuscular group. Although the study indicates a significant increase in serum levels achieved by the oral route, the follow-up period of patients under study is too early to evaluate its clinical effectiveness as compared to the intramuscular route.

Adenocarcinoma↗