Abstract
The effect of phenylbutazone (PBZ) on the in vivo serum protein binding of sulfadimethoxine (SDM) was examined in dogs, rabbits and rats. In dogs, PBZ itself was found to displace SDM from its protein binding sites. In rabbits, PBZ indirectly reduced the in vivo serum protein binding of SDM through the interaction of PBZ with N4-acetylsulfadimethoxine (N4-AcSDM), a major metabolite of SDM. In rats, however, PBZ had no effect on the in vivo serum protein binding of SDM. It is noteworthy that species differences were observed in the effect of PBZ on the in vivo serum protein binding of SDM.
