Thaker, A. M.MARADIYA, JAYESH JASAMAT2018-05-222018-05-222004http://krishikosh.egranth.ac.in/handle/1/5810047157The present study was conducted to determine the pharmacokinetics of ceftriaxone after single dose intravenous and intramuscular administration in Kankrej X Jersey crossbred calves. The ceftriaxone concentration in plasma was determined by High Performance Liquid Chromatography (HPLC). Following single dose (10 mg/kg of body weight) intiavcnous administration of ceftriaxone, the therapeutically effective plasma drug concentration (> 0.1 µg ml-1) was maintained for up to 8 hours. Pharmacokinetics of the drug was best described by a two-compartment open model following intravenous administration. The drug was rapidly distributed [t1/2α 0.13 ± 0.01 h; Vd(area): 0.44 ± 0.07 L kg-1] and eliminated (t t1/2β, 1.58 ± 0.06 h) from the body with a clearance rate of 3.15 ± 0.41 ml min-1kg-1. Following single dose intramuscular administration of ceftriaxone at the rate of 10 mg/kg of body weight in calves, the therapeutically effective plasma drug concentration was detectable at 0.083 hour (5 minutes) and maintained for 12 hours. Peak plasma concentration (15.34 ± 2.39 µg ml-1) was obtained at 0.25 hour after intramuscular administration. The drug was rapidly absorbed from the site of injection (t 1/2, Ka: 0.26 ± 0.04 hour), widely distributed [Vd,area); 1.16 ± 0.15 L kg-1] and slowly eliminated from the body (t 1/2β:5.02 ± 0.51 hours). The bioavailability of ceftriaxone was 0.45 ± 0.04 (45 ± 4 per cent) following intramuscular injection. The studies indicate that a satisfactory intravenous dosage regimen of ceftriaxone in calves would be 4.15 mg/kg of body weight given at 12 hour interval. However, ceftriaxone can also be given intramuscularly in calves at the rate of 10 mg/kg of body weight repeated at 12 hour interval. A more practical approach would be to administer intravenous loading dose (4.15 mg/kg of body weight) followed by intramuscular maintenance dose (10 mg/kg of body weight) repeated at 12 hour interval. The recommended doses need to be evaluated in clinical situations to establish their efficacy.enVETERINARY PHARMACOLOGYA STUDYThesis