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viene descritto un metodo di cromatografia liquida ad alta pressione (HPLC) in fase inversa per determinazione quantitativa di aminofenazone e clortenossazina in una forma farmaceutica

An in vivo investigation of paracetamol availability was carried out on eight healthy volunteers, comparing two paracetamol suppository formulations prepared using two different gliceride bases, a fast drug-releasing one and a slow drug-releasing one, i.e. Witepsol H15 and W35, respectively. The formulations were selected on the basis of a previous in vitro drug release study, which showed that, by superimposing the excipients in two layers within the same suppository, the drug release kinetics could be modulated using different ratios between the two layers. The comparison between the two different formulations in terms of plasma profiles and total amounts of drug excreted in urine revealed an increase in the extent of drug absorption from the layered excipient suppository. As the W35 has a higher monoglyceride content than the H15, this improved paracetamol availability could be ascribed to the absorption-enhancing effect of the monoglycerides. Moreover, the W35 has also a higher viscosity, which could possibly cause the suppository to be retained for a longer time in the lower part of the rectum, where the blood is drained directly to the systemic circulation. It was therefore hypothesized that the enhanced paracetamol availability could be also due to a liver bypass mechanism. For a further examination of the paracetamol absorption kinetics after rectal administration, a one-compartment model was fitted to the drug plasma concentration data. This approach allowed to draw absorption versus time profiles, which showed that a retardation actually occurred in paracetamol absorption when using suppositories containing the slow drug releasing excipient W35. These absorption data were then employed for an A level in vitro-in vivo correlation testing, and a linear relationship was found between in vitro release rate and in vivo absorption rate, both for fast releasing and for the layered excipient suppositories.

A rapid and specific high-performance liquid chromatographic assay for the quantitative determination of angiotensin-converting enzyme activity is described. Hippuryl- l -histidyl- l -leucine (Hip—His—Leu) is used as substrate and the released hippuric acid is measured. The procedure is accurate and precise and no extraction is required.

A reversed-phase high-performance liquid chromatographic method has been developed to determine paracetamol, caffeine and propyphenazone in a typical tablet formulation with high accuracy and precision. The mobile phase is a linear water-methanol gradient.

A simple method for measuring angiotensin-converting enzyme activity in human serum was developed. Samples were incubated with hippurylhistidylleucine and the liberated hippuric acid was determined directly by reversed phase ion-pair high-performance liquid chromatography with UV spectrometric detection.