Diclofenac was responsible for the decimation of Gyps vulture species on the Indian subcontinent during the 1980s and 1990s. Gyps vultures are extremely sensitive (the lethal dose 50 [LD50] ~ 0.1 mg/kg - 0.2 mg/kg), with toxicity appearing to be linked to metabolic deficiency, demonstrated by the long T1/2 (~12 h - 17 h). This is in striking comparison to the domestic chicken (Gallus gallus domesticus), in which the LD50 is ~10 mg/kg and the T1/2 is ~1 h. The phase 1 cytochrome P450 (CYP) 2C subfamily has been cited as a possible reason for metabolic deficiency. The aim of this study was to determine if CYP2C9 homolog pharmacogenomic differences amongst avian species is driving diclofenac toxicity in Gyps vultures. We exposed each of 10 CYP-inhibited test group chickens to a unique dose of diclofenac (as per the Organisation for Economic Co-operation and Development [OECD] toxicity testing guidelines) and compared the toxicity and pharmacokinetic results to control group birds that received no CYP inhibitor. Although no differences were noted in the LD50 values for each group (11.92 mg/kg in the CYP-inhibited test group and 11.58 mg/kg in the control group), the pharmacokinetic profile of the test group was suggestive of partial inhibition of CYP metabolism. Evaluation of the metabolite peaks produced also suggested partial metabolic inhibition in test group birds, as they produced lower amounts of metabolites for one of the three peaks demonstrated and had higher diclofenac exposure. This pilot study supports the hypothesis that CYP metabolism is varied amongst bird species and may explain the higher resilience to diclofenac in the chicken versus vultures.

Enrofloxacin (ENR) is a wide broad-spectrum antibacterial drug used widely in veterinary medicine. It was aimed to investigate the pharmacokinetic behavior of ENR in Kilis goats at single dosage of 2.5 mg/kg per goat body weight (bw) in the present study. A total of 10 healthy Kilis male goats were divided into 2 groups: each including 5 animals for the pharmacokinetic studies Group I, received 2.5 mg/kg via vena jugularis by IV route; Group 2 received the same dose by intramuscular route through administration at musculus semitendinosus at formulation. Group 1 blood samples were taken at 0.08, 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 8, 12, 18, 24, 36 and 48 hours and Group 2 blood samples were taken at 0.25, 0.5, 0.75, 1, 1.5, 2, 4, 8, 12, 18, 24, 36 and 48 hours after administration of drug. ENR and its metabolite, ciprofloxacin (CPR) analysis was performed by high-performance liquid chromatography. Maximal plasma concentration (Cmax 0.77 ± 0.05 μg/ml for IM) was reached at 1.00 h (Tmax) for IM. The elimination half-life (T1/2) of ENR was of 21.09 ± 0.87 h for IV and 29.75 ± 2.50 h for IM. The values of area under concentration-time curve (AUC) of ENR were of 6.46 ± 0.52 and 4.11 ± 0.35 μg.h/ml. ENR bioavailability (F) was calculated as 63.62%. The elimination half-life of CPR was of 19.31 ± 2.15 h for IV and 33.42 ± 1.28 h for IM.

Chlortetracycline (CTC) is a broad-spectrum antibiotic belonging to the tetracycline group of drugs. It is commonly used in the poultry industry for the treatment of bacterial infections and is also used as a growth promoter. This study was aimed at validating the sensitive HPLC method for the assay of CTC in chicken plasma. The method consisted of isocratic elution with separation using a C]8 column. The mobile phase used in the study was aqueous oxalic acid (0.03M), acetonitrile and methanol in the ratio of 60:30:10. The HPLC conditions included a flow rate of Iml/min with UVdetection at 375nm. CTC in chicken plasma was extracted with Mcllvaine buffer followed by dilution with water in the ratio of 1:1 andfiltered using 0.22p filters. The peak of chlortetracycline was noticed at 5-6 minis. The method was linear from 0.05mg/ml to 10mg/ml. The recovery percentage from plasma was recorded as 110%. Thus, from this study it is inferred that this method is optimal for the assay of CTC in plasma for pharmacokinetic studies.

Ceftizoxime is the third generation cephalosporin, extensively used in veterinary medicine. It has larger volume of distribution, good penetration into tissues, and useful for the treatment of mastitis which is resistant to other antibiotics. Keeping in view of generating pharmacokinetic data of ceftizoxime in different domestic animals, the present study was planned to investigate pharmacokinetics of ceftizoxime in goats (n = 6) at the dose rate of 10mg kg-1 body weight following single dose intravenous administration. Drug concentration in plasma was determined using High Performance Liquid Chromatography (HPLC) with UV detector. The values of Cmax, AUC and MRT were 44.40 ± 2.09 µg ml-1, 121.22 ± 15.40µg.h.ml-1 and 11.44 ± 1.30 h, respectively. The longer elimination half-life (8.92 ± 1.11h) along with smaller ClB (0.09 ± 0.01 Lh-1 kg-1) showed slower excretion of the drug from animal body. 

Ceftizoxime is the third generation cephalosporin, extensively used in veterinary medicine. It has larger volume of distribution, good penetration into tissues, and useful for the treatment of mastitis which is resistant to other antibiotics. Keeping in view of generating pharmacokinetic data of ceftizoxime in different domestic animals, the present study was planned to investigate pharmacokinetics of ceftizoxime in goats (n = 6) at the dose rate of 10mg kg-1 body weight following single dose intravenous administration. Drug concentration in plasma was determined using High Performance Liquid Chromatography (HPLC) with UV detector. The values of Cmax, AUC and MRT were 44.40 ± 2.09 µg ml-1, 121.22 ± 15.40µg.h.ml-1 and 11.44 ± 1.30 h, respectively. The longer elimination half-life (8.92 ± 1.11h) along with smaller ClB (0.09 ± 0.01 Lh-1 kg-1) showed slower excretion of the drug from animal body.