1.Oral bioavailability of sulphonamides in ruminants: a comparison between sulphamethoxazole, sulphatroxazole, and sulphamerazine, using the dwarf goat as animal model.
Rátz V1, Maas R, Semjén G, van Miert AS, Witkamp RF. Vet Q. 1995 Sep;17(3):82-7.
The various sulphonamides show marked differences in disposition characteristics after administration to ruminants. For use in combination with a diaminopyrimidine derivative such as trimethoprim or baquiloprim, it is essential that a sulphonamide has similar pharmacokinetic properties in order to obtain optimal synergy. In the present study the pharmacokinetics of sulphamethoxazole, sulphatroxazole, and sulphamerazine were investigated in dwarf goats (n = 6) after IV and intraruminal administration at a dose of 30 mg/kg bodyweight. In addition, the in vitro binding of sulphamerazine to ruminal contents was studied as a possible explanation for a reduced absorption rate. Sulphamethoxazole showed the most rapid absorption after intraruminal administration (mean tmax +/- SD : 0.8 +/- 0.2h). However, the drug was rapidly eliminated from the plasma (t1/2 beta : 2.4 +/- 1.5 h) and the bioavailability was only 12.4 +/- 4.7%, most likely due to an extensive 'first-pass' effect.
2.Pharmacokinetics of baquiloprim and sulphadimidine in pigs after intramuscular administration.
Davies AM1, MacKenzie NM. Res Vet Sci. 1994 Jul;57(1):69-74.
Baquiloprim, a novel 5-substituted 2, 4-diaminopyrimidine, has been developed specifically for veterinary use. It has been formulated as an injectable preparation and combined with sulphadimidine to exploit the synergistic activity of the two antibacterial agents. The formulation was given by deep intramuscular injection to pigs at doses of 10 mg kg-1 and 30 mg kg-1 and the pharmacokinetic properties were investigated. The in vitro activity of the two components was also determined against a range of porcine pathogens. Both components were rapidly absorbed and the maximum concentrations of 0.55 microgram ml-1 baquiloprim and 15.6 micrograms ml-1 sulphadimidine observed after the administration of the lower dose were well in excess of the minimum inhibitory concentration (MIC) values against susceptible pathogens, the highest combined MIC90 being 0.06 microgram ml-1 baquiloprim + 6.25 micrograms ml-1 sulphadimidine. Concentrations above the MIC values of most pathogens were maintained for more than 24 and 48 hours after the administration of the lower and higher doses, respectively.
3.Eimeria alabamensis coccidiosis in grazing calves: control by a long-acting baquiloprim/sulphadimidine bolus.
Svensson C1, Olofsson H. Appl Parasitol. 1996 Sep;37(3):168-76.
The excretion of Eimeria oocysts, the faecal dry matter and the weight gain of three groups of 12 calves, were compared during their first 20 days of grazing on a pasture known to have been contaminated with oocysts of Eimeria alabamensis during the previous year. On the day of turnout (day 0) the calves in group 1 were each treated with one bolus per 200 kg bodyweight containing 1.6 g baquiloprim and 14.4 g sulphadimidine. The calves of group 2 received the same treatment on day 3, and the calves of group 3 were left untreated. Eleven of the untreated calves developed clinical coccidiosis due to E. alabamensis and excreted more than 850,000 oocysts/g of faeces 8-10 days after turnout. Seven of the calves in group 1 and five of those in group 2 developed diarrhoea, but it was milder and/or less persistent than in the untreated calves. The treated calves excreted significantly fewer oocysts and lost significantly less weight than the untreated calves.
4.Validation of a microbiological method: the STAR protocol, a five-plate test, for the screening of antibiotic residues in milk.
Gaudin V1, Maris P, Fuselier R, Ribouchon JL, Cadieu N, Rault A. Food Addit Contam. 2004 May;21(5):422-33.
The results of an in-house laboratory validation of a microbiological method for the screening of antibiotic residues in milk are presented. The sensitivity of this five-plate test, called Screening Test for Antibiotic Residues (STAR), was established by the analysis of milk samples spiked with 66 antibiotics at eight different concentrations. Ten different groups of antibiotics were studied: macrolides, aminoglycosides, cephalosporins, penicillins, quinolones, tetracyclines, sulphonamides, lincosamides, phenicolated and miscellaneous drugs. It was shown that 21 antibiotics were detected by the STAR protocol at or below the maximum residue limit (MRL), and that a further 27 drugs could be detected at levels from the MRL up to four times the MRL. The sensitivity of the STAR protocol was at or below the MRL for three macrolides, one tetracycline, two aminoglycosides, some sulphonamides, half of the beta-lactams, quinolones, lincosamides, trimethoprim and baquiloprim.