Comparative pharmacokinetics of sulfamethazine in plasma and parotid saliva of sheep

Abstract

Salivary output in sheep is large enough to be considered a physiologic body fluid compartment. The hypothesis for this work was that pharmacokinetics of sulfamethazine in saliva was similar to that in plasma. A reliable technique was developed to measure parotid salivary output. Mean output of saliva was 3.18 +/- 1.04 L from a single parotid gland per day with a mean flow of 2.21 +/- 0.43 mL/min. Using concentrations of sulfamethazine in parotid saliva made it possible to calculate the total passage of sulfamethazine to parotid saliva, which was calculated to be 3.5% of the total dose. Pharmacokinetic variables obtained for sulfamethazine in plasma and in saliva were closely related (AUC 1408 micrograms.h/mL and AUC 1484 micrograms.h/mL; Vdarea 0.434 L/kg and Vdarea 0.374 L/kg; t 1/2 beta 4.30 h and 3.46 h, respectively) and no substantial differences were observed. The convenience of using salivary concentrations of sulfamethazine for drug monitoring is discussed.

Comparative pharmacokinetics of sulfamethazine after intravenous administration in bovine (Bos taurus) and buffalo (Bubalis bubalis) calves

“…This result is similar to those reported by Srivastava et al. (1989) (76.2 μ g/mL after 18 h in cross‐breed bovines) and Pulido et al. (1998) (58–65 μ g/mL after 12 h in sheep).…”

Effects of age on the pharmacokinetics of single dose sulfamethazine after intravenous administration in cattle

“…Sulfamethazine is classified as a long-acting sulphonamide (Spoo and Riviere 2001), but in our work, sulfamethazine plasma concentrations remains above 50 μg/mL for 21.38± 2.21 h; 21.20±3.3 h; 15.63±2.16; 14.45±3.23 h in one, three, seven and fifteen-week-old calves, respectively; therefore, sulfamethazine behaved as an intermediate-acting sulphonamide in all age groups. Our results are similar to those reported by Srivastava et al (1989), Pulido et al (1998) and Baroni et al (2007).…”

“…Forestomachs are little developed and relatively non-functional in newborn ruminants. Non-ionized drugs and those with good lipid solubility, pass in either direction across rumen epithelium by a passive diffusion mechanism (Atef et al 1981;Pulido et al 1998). Nouws et al (1989) administered sulfamethazine in ruminants of two different ages (twelve and eighteen weeks-old) and they observed a longer persistence of sulphadimidine at eighteen weeks-old compared to the twelve weeks-old calves (a lower total body clearance and a prolonged elimination of this drug were found in the older animals).…”