Quantitation of cefazolin sodium in plasma and tissues by high-performance liquid chromatography

Abstract

A sensitive and reproducible HPLC method for the determination of cefazolin sodium in plasma and tissues of albino rats was developed. The assay technique utilizes a simple methanol extraction of the antibiotic and sulfamethoxazole or succinyl sulfathiazole as the internal standard. The proteins in plasma or tissue homogenates were precipitated by the addition of concentrated solution of trichloroacetic acid. Separation of the drug was performed on a μBondapak C 18 column using a 0.1 M sodium acetate buffer (pH 3.85): acetonitrile (89:11) mobile phase and the eluent was monitored at 254 nm. The limits of detection were 0.1 μg/ml of plasma and 1 μg/g tissue, and the linearity ranges were 0.1–200 μg/ml of plasma and 1–40 μg/g tissue. An excellent linear correlation was observed between the peak height ratios and the cefazolin concentration ( r 2 = not less than 0.999). Minimum and maximum coefficient of variation were 2.54% and 3.12%, respectively, for the plasma and 2.17% to 3.51% and 0.82% to 3.06% for tissues at the concentration levels of 2 μg/ml (g) and 20 μg/ml (g), respectively. The method has been used to study cefazolin physiological pharmacokinetics in more than 80 rats and has been proven to be reproducible and sensitive.