Pharmacokinetics and urinary excretion of sulphadimidine in sheep during summer and winter

Abstract

Pharmacokinetics and urinary excretion of sulphadimidine were investigated in sheep during summer and winter seasons. Average minimum and maximum environmental temperature in the summer ranged from 22.6 to 40.2 degrees C and in winter from 4.5 to 21.1 degrees C. The determination of plasma volume, plasma protein and packed cell volume during summer and winter revealed a significant decrease in plasma volume and a significant increase in plasma protein in the summer indicative of haemoconcentration. Packed cell volume did not differ significantly between the seasons. The pharmacokinetics of sulphadimidine were determined following a single intravenous injection (100 mg/kg) in summer and winter. Zero time plasma concentration of the drug was higher during summer than in winter. The elimination half-life of the drug was similar in summer and winter, but the apparent volume of distribution was lower in summer. Likewise, total body clearance was significantly lower in summer. Based on these studies a satisfactory intravenous dosage regimen might consist of 86 and 100 mg/kg for priming and 78 and 88 mg/kg as maintenance doses during summer and winter, respectively, the doses being repeated at 12 hour intervals. Twenty four hours after sulphadimidine administration 90 and 73 per cent of the dose was excreted in urine during summer and winter, respectively. The drug was excreted mainly as free amine.

Pharmacokinetics, safety and tissue residues of sustained‐release sulfamethazine in sheep

“…The pharmacokinetic parameters calculated from the data obtained in the present study are in very good agreement with parameters calculated by Youseff et al (198 1). Bevill et al (1977), Nawaz and Khan (1979) and Nawaz and Nawaz (1983) are similar. Each of these teams used a singlecompartment model to evaluate their plasma profile data.…”

“…Considerable work has been done to evaluate the pharmacokinetics of SMZ in sheep Nawaz 8c Kahn, 1979;Youseff et al, 1981; Nawaz 8c Nawaz, 1983); however, no reports of the kinetics-of a sustained-release bolus formulation have been published.…”

Daily rhythms in blood and milk lead toxicokinetics following intravenous administration of lead acetate to dairy cows in summer

“…The V ss observed in the present summer study were slightly lower than those recorded in winter (Valtorta et al 2003). Lower volumes of distribution of sulphadimidine were found during summer in sheep, and were explained on the basis of the hemoconcentration revealed by a decrease in plasma volume and an increase in plasma proteins in that season (Nawaz and Nawaz 1983). Houpert et al (1995) found V ss values between 16 and 35 L/ kg for cadmium in sheep.…”

“…This situation could determine a certain degree of hemoconcentration. Nawaz and Nawaz (1983) found that sheep show a summer decrease in plasma volume, which determines a certain extent of hemoconcentration. However, Lee et al (1987) reported a slight winter hemoconcentration in women.…”

Disposition kinetics of erythromycin in normal and experimentally-induced febrile rabbits

“…Total area under the plasma concentration versus time curve (AUCO-oo) in normal and febrile rabbits was not significantly different; however, total area under the first moment curve (AUMCo-o) in febrile rabbits was significantly (P < 0.05) higher than that in the normal rabbits. Mean values for elimination rate constant (K e ) were significantly (P < 0.01) lower in 1 Albumin (g/dl)…”