Radioreceptor assay for ergot derivatives, transdihydrolisuride and lisuride, in biological fluids.

The development of a sensitive radioreceptor assay (RRA) for transdihydrolisuride (TDHL) and lisuride, as well as the synthesis of tritiated TDHL, is described. The method is based upon the competition between 3H TDHL and TDHL or lisuride for rat brain dopaminergic receptors. Linear calibration graphs were obtained in the range of 0.2-9 pmol for an ergot derivative. Relative affinities of the main metabolites, deethylated and dideethylated on the urea part of the molecule are 3.6% and 1.5%, respectively, as compared to the parent drug. To verify the method, plasma levels of TDHL were determined in rats after oral administration.

High-performance liquid chromatographic determination of terguride in solid dosage forms and plasma.

A simple and rapid HPLC method was developed to determine terguride in terguride hydrogenmaleate, coated tablets and plasma. The assay was carried out on a glass column of SGX CN (150 x 3.3 mm I.D.) using methanol and phosphate buffer solution (pH 7.0) as the mobile phase, with detection at 227 nm. Terguride was quantified using promethazine as an internal standard. The tablet matrix was extracted into methanol. Plasma samples were deproteinated with acetonitrile and the supernatant was injected into the HPLC system. The method is linear, quantitative and reproducible.