title: Pharmacokinetics and therapeutic potential for repeated oral doses of trimethoprim/sulphachlorpyridazine in horses.
abstract: The pharmacokinetic parameters of a powder formulation of trimethoprim/sulphachlorpyridazine were studied in eight healthy horses which received 5 mg/kg trimethoprim and 25 mg/kg sulphachlorpyridazine 12-hourly with concentrate for five days. The intake of the medicated concentrate by the horses was variable during the first two days, but after they became accustomed to the taste the intake by all the horses during the last three days was good. Faecal samples taken before and on the last day of the drug administrations were negative when cultured for salmonella. Compared with the results of a previous single-dose experiment, higher plasma concentrations and a higher area under the curve for both the drugs were observed. The repeated doses provided plasma concentrations above the minimal inhibitory concentration for Streptococcus zooepidemicus, S equi, Actinobacillus equuli and Rhodococcus equi isolated from the respiratory tract of horses. Synergism between the two drugs occurred at different drug concentration ratios with different bacterial species.
authors.affiliation: Department of Large Animal Medicine and Nutrition, Veterinary Hospital Pharmacy, Utrecht, The Netherlands.
authors.forename: E
authors.initials: E
authors.lastname: van Duijkeren
authors.forename: M M
authors.initials: MM
authors.lastname: Sloet van Oldruitenborgh-Oosterbaan
authors.forename: A G
authors.initials: AG
authors.lastname: Vulto
authors.forename: B G
authors.initials: BG
authors.lastname: Kessels
authors.forename: A S
authors.initials: AS
authors.lastname: van Miert
authors.forename: H J
authors.initials: HJ
authors.lastname: Breukink
mesh_terms: D000284:Administration, Oral; D000818:Animals; D000900:Anti-Bacterial Agents / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use; D001419:Bacteria / Q000187:drug effects; D004338:Drug Combinations; D004357:Drug Synergism; D005260:Female; D006736:Horses / Q000378:metabolism* / Q000382:microbiology; D008297:Male; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D012137:Respiratory System / Q000382:microbiology; D013410:Sulfachlorpyridazine / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use; D014295:Trimethoprim / Q000493:pharmacokinetics* / Q000494:pharmacology / Q000627:therapeutic use
chemical_list: D000900:Anti-Bacterial Agents; D004338:Drug Combinations; D014295:Trimethoprim; D013410:Sulfachlorpyridazine