Submicrogram assay for scopolamine in plasma and urine.

A GLC-mass spectrometric method for scopolamine, sensitive to 50 pg/ml for a 4-ml plasma or urine sample, was developed. The method used a deuterated internal standard to minimize variability in absolute recovery in the extraction procedure. Scopoline and deuterated scopoline were formed from the base-catalyzed hydrolysis of scopolamine and the internal standard and were analyzed as the heptafluorobutyrates, using a GLC-mass spectrometric system by monitoring the m/e 138 and 141 fragments, respectively.

High-performance liquid chromatographic determination of acetylcholine in a pharmaceutical preparation.

A simple and rapid method for quantitating acetylcholine in a lyophilized preparation by high-performance liquid chromatography (HPLC) is described. A reverse-phase column with a refractive index detector was utilized for the assay. The HPLC system was able to separate acetylcholine from choline, a major degradation product, which was verified by running a degraded sample of a commercial preparation. The HPLC results were compared with the results obtained by a spectrophotometric procedure.

Subnanogram assay for pilocarpine in biological fluids.

A method for the determination of pilocarpine was developed in which the imidazole ring of pilocarpine was acylated with heptafluorobutyric anhydride, using triethylamine as a catalyst. After cleanup, the pilocarpine derivative was analyzed using GLC with electron-capture detection. The limit of sensitivity was 25-50 pg of pilocarpine, which had been subjected to the derivatization and cleanup procedures. The method was specific for pilocarpine, with the isopilocarpine derivative eluting prior to the pilocarpine derivative.

Time course and disposition of methazolamide in human plasma and red blood cells.

Methazolamide was determined in plasma, whole blood, and urine by a GLC-mass spectrometric method. Temporal patterns of methazolamide concentrations in plasma and red blood cells were obtained following single- and multiple-dose oral administration of the drug. The nonlinearity in the binding of the drug to the red blood cell carbonic anhydrase was evident from a comparison of plasma and red blood cells concentrations. The drug was cleared slowly from the red blood cells. The binding constants to the two isoenzymes of carbonic anhydrase were determined from the plasma and red blood cell concentrations and were in agreement with those determined by previous measurements. The half-life of elimination was 7.5 hr. The urinary recovery of unchanged drug was approximately 25% of the administered dose.

Determination of submicrogram quantities of clonidine in biological fluids.

A sensitive and specific GLC method using electron-capture detection was developed for clonidine in plasma and urine. Di-perfluoroacyl derivatives of both clonidine and the 4-methyl analog of clonidine (used as an internal standard) were formed, and an extraction process was developed for the removal of excess derivatization reagent and endogenous biological compounds; the assay permitted quantification of 25 pg of clonidine/ml in a 4-ml plasma sample. The assay was used to elucidate the time course of plasma concentrations in a normotensive subject following oral administration of 50, 100, and 200 microgram of clonidine hydrochloride and also to determine unchanged drug excreted in the urine.