The pharmacokinetics of orally administered S-carboxymethyl-L-cysteine in the dog, calf and sheep.

The aim of this study was to investigate the feasibility of employing S-carboxymethyl-L-cysteine as a treatment of chronic obstructive pulmonary disease in dogs. To this end the pharmacokinetic parameters of orally administered S-carboxymethyl-L-cysteine were determined in the dog, cow and sheep. Six healthy beagle dogs, six endogenous Greek sheep and four Holstein Fresian calves were orally dosed with 10 mg/kg body weight of S-carboxymethyl-L-cysteine. No significant differences in T(max) and T(1/2) were reported between the species. However, significantly higher AUC((0-last)), 21.56+/-6.67 microg h ml(-1) and AUC((0-infinity)), 21.63+/-6.68 microg h ml(-1) were seen in the dogs compared to the sheep and calves. The calculated V(D) was significantly higher in the sheep (10.4+/-2.7 L kg(-1)) and the calves (3.8+/-0.7 L kg(-1)) compared to the dogs (1.0+/-0.6 L kg(-1)). The rank order of increasing C(L) was sheep (3.4+/-2.7 L h(-1)kg(-1))>calves (2.7+/-0.4 L h(-1) kg(-1))>dogs (0.5+/-0.2 L h(-1)kg(-1)). The result for the dogs was significantly lower that the calculated C(L) for the sheep and calves. All these results indicate that the oral administration of S-carboxymethyl-L-cysteine may be useful during the therapeutic management of chronic obstructive pulmonary disease in dogs.