No abstract

No abstract

No abstract

1. The pharmacokinetics of gatifloxacin were investigated following intravenous and oral administration of a single dose at a rate of 10 mg/kg body weight in broiler chicks. 2. Drug concentration in plasma was determined using High Performance Liquid Chromatography with ultraviolet detection on samples collected at frequent intervals after drug administration. 3. Following intravenous administration, the drug was rapidly distributed (t(1/2α): 0·33 ± 0·008 h) and eliminated (t(1/2β): 3·62 ± 0·03 h; Cl(B): 0·48 ± 0·002 l/h/kg) from the body. 4. After oral administration, the drug was rapidly absorbed (C (max): 1·74 ± 0·024 µg/mL; T (max): 2 h) and slowly eliminated (t(1/2β): 3·81 ± 0·07 h) from the body. The apparent volume of distribution (V(d(area))), total body clearance (Cl(B)) and mean residence time (MRT) were 3·61 ± 0·04 l/kg, 0·66 ± 0·01 l/h/kg and 7·16 ± 0·08 h, respectively. The oral bioavailability of gatifloxacin was 72·96 ± 1·10 %. 5. Oral administration of gatifloxacin at 10 mg/kg is likely to be highly efficacious against susceptible bacteria in broiler chickens.

Rhesus monkeys are a non-rodent species employed in the preclinical safety evaluation of pharmaceuticals and biologics. These nonhuman primate species have been increasingly used in biomedical research because of the similarity in their ionic mechanisms of repolarization with humans. Heart rate and QT interval are two primary endpoints in determining the pro-arrhythmic risk of drugs. As heart rate and QT interval have an inverse relationship, any change in heart rate causes a subsequent change in QT interval. This warrants for calculation of a corrected QT interval. The objective of this study was to identify an appropriate formula that best corrected QT for change in heart rate. We employed seven formulas based on source-species type, clinical relevance, and requirements of various international regulatory guidelines. Data showed that corrected QT interval values varied drastically for different correction formulas. Equations were further compared on their slope values based on QTc versus RR plots. The rank order of the slope for different formulas was (closest to farthest from zero) QTcNAK, QTcHAS, QTcBZT, QTcFRD, QTcVDW, QTcHDG, and QTcFRM. QTcNAK emerged to be the best correcting formula in this study. It showed the least correlation with the RR interval (r= -0.01) and no significant difference amongst the sexes. As there is no universally recognized formula for preclinical use, the authors recommend developing a best-case scenario model for specific study designs and individual organizations. The data from this research will help decide the appropriate QT correction formula for the safety assessment of new pharmaceuticals and biologics.