Enzyme immunoassay for flecainide.

In order to develop an enzyme immunoassay (ELISA) for measurement of plasma flecainide levels, we first synthesized flecainide-hemisuccinate-BSA as immunogen. A highly specific antiserum was then raised in rabbits. Enzyme-labelled flecainide was prepared by the mixed anhydride method using hemifumarate-flecainide and horse radish peroxidase. The limit of detection was 10 ng/ml, the method was linear up to 1,000 micrograms/l. The intra and inter-assay variation was 5.1-7.8%. Cross reactivity with various metabolites of flecainide or some chemically related drugs was less than 0.1%. By contrast the cross reaction with some structural analogues achieved 25%. The importance of parts of the aromatic ring structure in immunogenic properties of this drug is discussed.

Development of an ELISA to study the polymorphism of dextromethorphan oxidation in a French population.

Simple, sensitive and selective enzyme immunoassays (ELISA) for monitoring urinary dextromethorphan and its major metabolite, dextrorphan, were developed. Dextromethorphan and dextrorphan hemisuccinates were linked to bovine serum albumin and specific antisera against each immunogen were raised in rabbits. The sensitivity of the ELISA was high (limit of detection 740 and 600 pg.ml-1 for dextromethorphan and dextrorphan, respectively). Intra- and interassay variation was less than 10%, and cross-reactivity between the two compounds was less than 1%. The ELISA was employed to phenotype 216 French subjects. The frequency of poor metabolizers was 5.1%.

[Variation in the urinary excretion of 6-beta-hydroxycortisol in humans after administration of the new isoquinoline derivative, PK-11195 (52028 RP)]. / Variation chez l'homme de l'excrétion du 6-beta-hydroxycortisol urinaire après administration d'un nouveau dérivé de l'isoquinoléine, PK-11195 (52028 RP).

Among in vivo tests to assess liver drug metabolizing enzyme induction, urinary 6-beta-hydroxycortisol (6-beta-OHF), plasma gamma-glutamyltransferase (GGT) and urinary D-glucaric acid are most frequently proposed. 6-beta-OHF is the most abundant unconjugated metabolite of cortisol in human urine. We measured its elimination during a clinical trial in 16 human healthy volunteers (men and women), these persons being treated by a new isoquinoleine derivative, 52028 RP (PK-11195). This drug is an antagonist of peripheral type benzodiazepine binding sites. Urinary excretion of 6-beta-OHF increased significantly (3.5 fold, p less than 0.01) on the 5th day of treatment (400 mg/day, orally) and remained increased as long as the treatment was continued (15 days). Control values were again observed 5 days after stopping the treatment. Plasma gamma-glutamyltransferase activity and D-glucaric acid urinary elimination are increased more than 2 fold. The data demonstrated that 6-beta-OHF in the most sensitive among the three tests performed to detect a drug metabolism induction, during this clinical trial.