Disposition of Isoniazid by Oral and Intravenous Administration in Cow Calf using RP-HPLC Method

In present experiment, Pharmacokinetic study of isoniazid (INH) was investigated in cow calf by using reverse phase high performance liquid chromatography (RP-HPLC) method. The determination INH was carried out after oral and intravenous administration in cow calves at a dose of 25 mg/kg body weight orally and 10mg/kg body weight intravenously. The blood samples of the animal receiving INH were collected at different time intervals of 15, 30 min, 1, 2, 4, 6, 8, 12, 24 and 48 hours for oral as well as intravenous administration. INH showed retention time of 5.8 min on using isocratic mobile phase made up of buffer (Sodium Dihydrogen orthophosphate pH- 6) and acetonitrile (96:4 ratio), with flow rate of 1 ml/min and C18 reverse phase column as used to detect INH at a wavelength of 265 nm after injecting 20 µl of samples with Pyrazinamide used as the internal standard. Pharmacokinetic parameters of the present study were calculated using PK Solver program by applying the one-compartmental model. After oral and intravenous administration, the mean Cmax, Tmax, AUC (0–24 h), CL, Vd,t1/2 and MRT of isoniazid for oral administration were observed to be 0.64 µg/ml, 1.31 hrs, 7.03 µg/mL*h, 394.01(mg/µg/ml)/h, 4691.79(mg)/µg/ml, 8.16 hrs and 12.05 hrs, respectively while that for intravenous administration it was 1.48 µg/ml, 0.25 hrs, 5.1 µg/mL*h, 168.45 (mg/µg/ml)/h, 566.68 (mg)/µg/ml, 2.42 hrs and 3.49 hrs respectively. By comparing the elimination t1/2 and MRT of INH by oral and intravenous route, it was observed that, the oral route of administration for INH was more convenient compared to intravenous administration. However, in view of acetylator status and age differences, the dose of 25 mg/kg body weight for oral administration may also be reduced and further investigation on low dose can be carried out.