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Plasma Concentrations and Pharmacokinetic Parameters of Nitrofenac Using a Simple and Sensitive HPLC Method

1995; Elsevier BV; Volume: 84; Issue: 1 Linguagem: Inglês

10.1002/jps.2600840121

1520-6017

G. Benoni, Alessandra Adami, L. Grigolini, Marta Terzi, Laura Cuzzolin, Piero Del Soldato,

Inflammatory mediators and NSAID effects

An accurate and sensitive HPLC method has been developed for the determination of nitrofenac, a new, original diclofenac derivate showing a good tolerability and a wide anti-inflammatory profile, diclofenac, and its metabolites in plasma. This method has been applied to evaluate the pharmacokinetic parameters of the drugs, using a noncompartmental model, after the oral administration of 5 mg/kg nitrofenac to rats. Nitrofenac and the internal standard flufenamic acid were dissolved in acetonitrile, and diclofenac was dissolved in methanol. The drugs were eluted from a 5 microns LC-8 column with a mobile phase consisting of acetonitrile/water (50/50 v/v) adjusted to pH 3.3 with glacial acetic acid, at a flow rate of 2 mL/min with UV detection at 280 nm for diclofenac and 275 nm for nitrofenac. The detection limit for the drugs in plasma was 25 ng/mL. The peak concentration of nitrofenac was reached 7 h after drug administration, while with diclofenac we observed three peaks at 2, 5, and 10 h; the mean residence time and the elimination rate constant for nitrofenac were 6.18 +/- 0.09 h and 0.37 +/- 0.03 h-1 respectively, while those for diclofenac were 12.24 +/- 0.11 h and 0.11 +/- 0.04 h-1. Under our conditions, the metabolism of nitrofenac produced 23% diclofenac and other metabolites: the plasma concentrations and kinetic characteristics of diclofenac are enough to induce an anti-inflammatory activity, while the clinical importance of the other metabolites remains to be elucidated.