Detection and quantification of low levels of benzoylecgonine in equine urine.

Cocaine (COC) is a highly addictive plant alkaloid expressing strong psychostimulatory effect. It has no medical use in equine veterinary practice. The contamination of the environment with cocaine such as its presence on the US paper currency has been reported few times. There are anecdotal reports of low benzoylecgonine (BE) concentrations (usually much less than 100 ng/mL) being found in urine of race horses. In order to protect horsemen against harsh penalties associated with the presence of trace amounts of BE in horse urine as a result of environmental contamination, in February 2005 the Illinois Racing Board issued new medication rules that established the threshold level of 150 ng/mL for BE in equine urine. The penalties associated with this rule provide for increasing fines ($250, $500, $1000) with successive positive reports against a trainer for levels of BE below 150 ng/mL. A total of 19,315 urine samples were collected over the 2-year period of time from winning horses (both harness and thoroughbred) at race tracks in Illinois for routine drug screening (ELISA). The presence of BE was confirmed by GC/MS in 28 urine samples (0.14%). The concentration range for BE in harness horses (21 detections) was < 5-91 ng/mL, and for thoroughbred (seven detections) was 7-52 ng/mL. To date, the laboratory has not reported concentrations of BE that exceed the established threshold concentration of 150 ng/mL.

Oxidation of raloxifene to quinoids: potential toxic pathways via a diquinone methide and o-quinones.

Raloxifene was approved in 1997 by the FDA for the treatment of osteoporosis in postmenopausal women, and it is currently in clinical trials for the chemoprevention of breast cancer. Before widespread use as a chemopreventive agent in healthy women, the potential cytotoxic mechanisms of raloxifene should be investigated. In the current study, raloxifene was incubated with GSH and either rat or human liver microsomes, and the metabolites and GSH conjugates were characterized using liquid chromatography-tandem mass spectrometry. Raloxifene was converted to raloxifene diquinone methide GSH conjugates, raloxifene o-quinone GSH conjugates, and raloxifene catechols. For comparison, three raloxifene catechols were synthesized and characterized. In particular, 7-hydroxyraloxifene was found to oxidize to the 6,7-o-quinone. As compared with raloxifene diquinone methide, which has a half-life of less than 1 s in phosphate buffer, the half-life of raloxifene 6,7-o-quinone was much longer at t(1/2) = 69 +/- 2.5 min. The stability offered by raloxifene 6,7-o-quinone implies that it may be more toxic than raloxifene diquinone methide. Cytotoxicity studies in the human breast cancer cell lines S30 and MDA-MB-231 showed that 7-hydroxyraloxifene was more toxic than raloxifene in both cell lines. These results suggest that raloxifene could be metabolized to electrophilic and redox active quinoids, which have the potential to cause toxicity in vivo.