Paul Lindberg

Radioimmunoassay of Norethindrone: Peripheral Plasma Levels After Oral Administration to Humans and Rhesus Monkeys

A radioimmunoassay for the measurement of norethindrone, utilizing an antiserum raised in sheep against norethindrone 3-(O-carboxymethyl) oximebovine serum albumin, and its application for determination of norethindrone concentrations in plasma is presented. The practical detection limit was .5 ng/ml plasma. No significant cross reaction was found for naturally occurring steroids. The cross reaction for d-norgestrel was 88% and for lynestrenol and R 2323 26%. Peripheral plasma levels of immunoreactive norethindrone were assayed at short intervals after oral administration of norethindrone in different doses to 6 human volunteers. Peak levels occurred within 1-2 hours. The plasma half-life of norethindrone was found to be about 3 hours during the first hours after ingestion and about 9 hours thereafter. A linear correlation was found between ingested dose per kg body weight and plasma peak levels. In 3 orally treated female rhesus monkeys the peak levels were lower and not as distinct as compared to that of the humans for the corresponding dose per kg body weight. The plasma half-life after the peak was about 8 1/2 hours.

Peripheral plasma levels of d-norgestrel in women after oral administration of d-norgestrel and when using intravaginal rings impregnated with dl-norgestrel

Abstract Peripheral plasma levels of progesterone, estradiol and d-norgestrel were determined by radioimmunoassay in five women using silastic intravaginal rings (IVR), homogenously impregnated with 50 mg of dl-norgestrel and in three women after oral intake of 250 and 30 μg of d-norgestrel. The radioimmunoassay for d-norgestrel utilized the crossreaction with a norethindrone antiserum. lodinated histamine was conjugated to d-norgestrel-3-(0-carboxymethyl)-oxime and the conjugate used as a tracer. It is concluded that this is a useful method for preparing a specific tracer for d-norgestrel. The plasma levels of progesterone and estradiol were depressed to early follicular phase levels during treatment with the IVRs. After an initial peak of 2.9–8.5 ng/ml on day 2–4, d-norgestrel levels decreased to 0.7–4.0 ng/ml at the end of treatment. Oral administration of 250 and 30 μg of d-norgestrel gave rise to peak plasma levels of 4–7 ng/ml and 1.1–2.8 ng/ml, respectively. The initial plasma half-life of d-norgestrel was found to be approximately three hours and the second half-life about 18 hours. A comparison between the plasma levels of d-norgestrel reached in women using IVRs and the levels reached after oral ingestion of d-norgestrel indicate that the rings used, during the main period of treatment, deliver more dnorgestrel than is needed for contraceptive purposes.

The influence of conjugated estrogens in radioimmunoassays using different antibodies against estradiol-17β

Abstract Estradiol-17β 17-D-glucoronide and estrone-3-sulphate were found to give minor crossreaction in radio-immunoassay systems for estradiol-17β using two different types of antibodies. The antibodies used were prepared in sheep against estradiol-17β 17-succinyl-bovine serum albumin and 6-ketoestradiol-17β 6-(0-carboxymethyl)oxime-bovine serum albumin. Only minute quantities of conjugated estrogens were extracted from plasma by diethyl ether (

Selenium concentration in kidneys of normal pigs and pigs affected with nutritional muscular dystrophy and liver dystrophy (Hepatosis diaetetica)

Abstract The selenium concentration was determined in normal pigs and in pigs affected with muscular and liver dystrophy. The mean value of normal pigs was 10.978 ± 0.568 p.p.m. of dry weight. Pigs affected with muscular dystrophy showed 3.397 ± 0.290 p.p.m., and pigs affected with liver dystrophy showed 3.325 ± 0.567 p.p.m.