Indirect atomic absorption determination of atropine, diphenhydramine, tolazoline, and levamisole based on formation of ion-associates with potassium tetraiodometrcurate.

Ion-associate complexes of atropine sulphate (I), diphenhydramine HCl (II), tolazoline HCl (III) and levamisole HCl (IV) with potassium tetraiodomercurate were precipitated and their solubilities were studied as a function of pH, ionic strength and temperature. Saturated solutions of each ion-associate under the optimum precipitation conditions were prepared and the metal ion-content in the supernatant was determined. The solubility products were thus calculated at different temperatures. A new accurate and precise method using atomic absorption spectrometry for the determination of the investigated drugs in pure solutions and in pharmaceutical preparations is described. The drugs can be determined by the present method in the ranges 13.6--138.8, 5.6-58, 3.6--39.6 and 4.8--48 microg/ml solutions of I--IV, respectively.

Isotachophoretic determination of bisoprolol, clonidine, disopyramide and tolazoline in human fluids.

Separation and determination of bisoprolol, clonidine, disopyramide and tolazoline in control serum and in human urine was investigated by capillary isotachophoresis. The drugs were separated by using the cationic electrolyte system. viz., sodium acetate buffer (pH 4.64) (c1 = 10 mM)-beta-alanine. The compounds were almost totally isolated from serum by solid-phase extraction using a Sep-Pak C18 cartridge. The recovery of compounds varied from 87 to 99%. The linear calibration range was studied to apply the method to real human fluids. The limit of determination of the drugs was 40.0 micrograms/ml serum. The limit of determination by direct sampling for bisoprolol is 3 micrograms/ml urine.

Quantitative determination of tolazoline in serum and urine.

A high-performance liquid chromatographic procedure is described for the analysis of tolazoline in serum and urine. This assay procedure is suitable for the analysis of micro-samples (50 or 100 microliters serum and 100 microliters urine). Samples are extracted in a single step and injected into a reversed-phase high-performance liquid chromatography system for detection at 210 nm. The clinical applicability of this assay is demonstrated by the determination of tolazoline serum and urine concentrations in neonates. In addition, the presence of urine conjugates and the extent of serum protein binding were investigated. This assay procedure has the required sensitivity (0.1 microgram/ml), accuracy and precision for both routine monitoring and pharmacokinetic characterization of tolazoline in neonates and adults.