RESUMO
It was found that the light emission produced by the oxidation of luminol by potassium ferricyanide in the basic medium was enhanced by phentolamine, a drug recently used to treatment of male and female sexual dysfunction. The optimum conditions for this chemiluminescent reaction were studied in detail by a flow-injection system. A new, simple and rapid method has been developed under the optimum conditions for determination of phentolamine. This method has the advantages of high sensitivity, good reproducibility and low detection limit. On the basis of investigation of chemiluminescent, fluorescent and UV spectra of phentolamine in basic solution containing potassium ferricyanide and luminol, a possible mechanism of this reaction was proposed. In the optimum conditions, CL intensities are proportional to concentrations of the phentolamine in the 0.01-1 microg/mL range. The limit of detection is 3.0 ng/mL for phentolamine. The method has been applied to the determination of phentolamine in the commercial preparations, synthetic samples and biological fluids with satisfactory results.
Assuntos
Ferricianetos/química , Análise de Injeção de Fluxo/métodos , Medições Luminescentes/métodos , Luminol/química , Fentolamina/química , Calibragem , Análise de Injeção de Fluxo/instrumentação , Humanos , Estrutura Molecular , Fentolamina/sangue , Fentolamina/urina , Reprodutibilidade dos Testes , Hidróxido de Sódio/química , Tecnologia Farmacêutica/métodosRESUMO
A method for the determination of unconjugated phentolamine at concentrations down to 5 ng/ml in human plasma, and of free and total (free plus conjugated) phentolamine down to 25 ng/ml in urine is described. After addition of 2-[N-(p-chlorophenyl)-N-(m-hydroxyphenyl)-aminomethyl]-2-imidazoline as internal standard, both compounds are extracted into benzene-ethyl acetate (1:1, v/v) at pH 10, transferred into an acidic aqueous solution and back-extracted at pH 10 into benzene-ethyl acetate. They are then derivatized with N-heptafluorobutyrylimidazole. The derivatives are determined by gas chromatography using a 63Ni electron-capture detector. In urine, total (free plus conjugated) phentolamine is determined after enzymatic hydrolysis. The technique was applied for the study of the plasma concentrations and urinary elimination after oral administration to man.
Assuntos
Fentolamina/sangue , Arilsulfatases , Cromatografia Gasosa , Glucuronidase , Humanos , Masculino , Microquímica , Fentolamina/urinaRESUMO
A reversed-phase, high-performance liquid chromatographic method using UV detection is described for the assay of the major metabolite of phentolamine in plasma and urine before or after enzymatic hydrolysis. Plasma is deproteinized with methanol. The sensitivity limit is 200 ng/ml using 150-microliters samples. Urine is either diluted with water or purified after enzymatic hydrolysis. Concentrations down to 2--3 micrograms/ml could be quantified with acceptable precision. This method was applied to plasma and urine samples from subjects given phentolamine.