Pharmacokinetics and distribution of sulphadimidine in plasma, milk and uterine fluid of female buffaloes.

The pharmacokinetics of sulphadimidine after a single dose (200 mg/kg i.v.) was studied in five healthy lactating buffaloes. The study revealed that the drug attained its peak concentration of 314.0 +/- 13.0, 242.4 +/- 3.0 and 100.2 +/- 2.5 micrograms/ml at 15 min, 30 min and 12 h in plasma, milk and uterine fluid, respectively. The pharmacokinetic parameters calculated by a 2-compartment open model gave values for t1/2 alpha, t1/2 beta and vdarea of 2.10 +/- 0.36 h, 12.36 +/- 0.57 h and 1.23 +/- 0.07 L/Kg, respectively. A high vdarea as well as a value of 0.74 +/- 0.08 for K12:K21-beta (tissue approximately equal to Plasma) indicates better penetration of the drug into the different body fluids and tissues, which is further supported by a high concentration obtained in milk and uterine fluid. The therapeutic concentration (greater than or equal to 50 micrograms/ml) was maintained for around 24 h in plasma and milk and 12 h in uterine fluid. The results suggest that, apart from its use in systemic infections, the drug can be effectively used by the i.v. route in uterine and mammary gland infections. The dosages for maintaining concentration of 50 micrograms/ml, 100 micrograms/ml and 150 micrograms/ml at convenient dosage intervals of 12 and 24 h were also determined.