Determination of nonsteroidal anti-inflammatory drugs in biological fluids by automatic on-line integration of solid-phase extraction and capillary electrophoresis.

A new, automatic method for the clean-up, preconcentration, separation, and quantitation of nonsteroidal anti-inflammatory drugs (NSAIDs) in biological samples (human urine and serum) using solid-phase extraction coupled on-line to capillary electrophoresis is proposed. Automatic pretreatment is carried out by using a continuous flow system operating simultaneously with the capillary electrophoresis equipment, to which it is linked via a laboratory-made mechanical arm. This integrated system is controlled by an electronic interface governed via a program developed in GWBasic. Capillary electrophoresis is conducted by using a separation buffer consisting of 20 mM NaHPO4, 20 mM beta-cyclodextrin and 50 mM SDS at pH 9.0, an applied potential of 20 kV and a temperature of 20 degrees C. The analysis time is 10 min and the detection limits were between 0.88 and 1.71 microg mL(-1). Automatic clean-up and preconcentration is accomplished by using a C-18 minicolumn and 75% methanol as eluent. The limit of detection of NSAIDs can be up to 400-fold improved when using sample clean-up. The extraction efficiency for these compounds is between 71.1 and 109.7 microg mL(-1) (RSD 2.0-7.7%) for urine samples and from 77.2 to 107.1 microg mL(-1) (RSD 3.5-7.1%) for serum samples.

Marked enantioselective protein binding in humans of ketorolac in vitro: elucidation of enantiomer unbound fractions following facile synthesis and direct chiral HPLC resolution of tritium-labelled ketorolac.

The protein binding of the enantiomers of the nonopiate analgesic, ketorolac, was investigated in vitro using human plasma and solutions of human serum albumin (HSA) at physiological pH and temperature. In order to detect the very low levels of unbound enantiomers in protein solutions, tritium-labelled rac-ketorolac was synthesised by regiospecific isotopic exchange of the parent drug with tritiated water as the isotope donor. Radiochemical purification of this compound by reversed-phase HPLC followed by direct resolution using a chiral alpha 1-acid glycoprotein (Chiral-AGP) HPLC column afforded labelled enantiomers of high specific activity. The in vitro use of (R)- and (S)-[3H4]ketorolac enabled reproducible radiometric detection of enantiomers in protein solution ultrafiltrate. The unbound fractions of (R)- and (S)-ketorolac [fu(R) and fu(S), respectively] were determined when drug was added to various plasma or albumin solutions as either the separate enantiomers or as the racemate. Over an enantiomeric plasma concentration range of 2.0-15.0 micrograms/ml, fu(S) (mean range: 1.572-1.795%) was more than 2-fold greater (P < 0.001) than fu(R) (mean range: 0.565-0.674%). Both fu(R) and fu(S) were constant over this concentration range, and each was unaffected by the presence of the corresponding antipode (P > 0.05). At a concentration of 2.0 micrograms/ml in 40.0 g/liter fatty acid-free HSA, fu(R) and fu(S) were approximately 0.5 and 1.1%, respectively, and both values declined with increasing concentrations of the long chain fatty acid, oleic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

The metabolism of zomepirac sodium. II. Isolation and identification of the urinary metabolites in rat, mouse, rhesus monkey, and man.

The metabolism of the oral analgesic agent, zomepirac sodium, sodium 5-(4-chlorobenzoyl)-1,4-dimethyl-1 H-pyrrole-2-acetate dihydrate, was studied in healthy male humans, rhesus monkeys, Wistar rats, and Swiss mice. The major urinary metabolites of zomepirac (Z) (80--95% of the dose) in these species were identified on the basis of a combination of chromatographic and spectroscopic data. Z was present as a major product in all species. Hydroxyzomepirac (HMZ) was a major component in rat and mouse, but a minor one in man, and it was absent in the monkey. 4-Chlorobenzoic acid (CBA) was identified as a major metabolite in rat (present as conjugates) and mouse and a minor one in monkey and man. Zomepirac glucuronide (ZG) was present as the major metabolite in man, monkey, and mouse, and present at trace levels in the rat. 4-Chlorohippuric acid, the glycine conjugate of CBA, was found in trace amounts only in the monkey. Thus, the metabolism of zomepirac in man and monkey is mainly characterized by glucuronide conjugation. The rat metabolizes zomepirac, mainly by oxidative pathways, to give HMZ and CBA. The mouse shows a balance of conjugation and oxidative pathways.