Theophylline radioimmunoassay: synthesis of antigen and characterization of antiserum.

Antisera to theophylline (T) have been obtained by immunizing rabbits with a conjugate of 8-(3-carboxypropyl)-1,3-dimethylxanthine and bovine serum albumin. Comparison of 50% displacement values indicated good selectivity for T vs. a number of other xanthine derivatives. An analytical procedure using this antiserum can measure 200 pg of T and direct analysis of 0.1 mug/ml in plasma or 0.02 mug/ml in saliva is feasible.

Norethynodrel metabolites in human plasma and urine.

PIP: Norethynodrel metabolites in human plasma and urine were analyzed. Samples were collected from healthy young women over 1 24-hour period after the oral administration of 11.1 mg (50 mcCi) of 6, 7-tritiated norethynodrel. The 3 alpha-hydroxy compound from the reduction of the 3-ketone of norethynodrel was the major free metabolite in plasma, with lesser amounts of its 3 beta-isomer and norethindrone. These compounds were identified by carrier addition analysis and their concentrations were estimated by thin-layer radiochromatography. The bulk of plasma metabolites consisted of conjugates and greater than 95% of urinary metabolites (20% of total dose) were conjugated; 2 of which were beta-glucuronides. Enzymatic hydrolysis enabled the urinary compounds to be identified by gas-lizuid chromatography-mass spectrometry. 70-80% (10% of the dose) of the enzymatically hydrolyzed urinary metabolites were hydroxylated compounds. Triols were the principal hydroxylated compounds isolated. The metabolism of norethynodrel was rapid and extensive.^ieng