APPENDIX B DRUG FORMULARY 811
Sulfadiazine (generic,combined withtrimethoprim inTribrissen)
Sulfonamides competewith PABA for enzymethat synthesizesdihydrofolic acid inbacteria. Synergistic withtrimethoprim. Broadspectrum of activity,including some protozoa.Bacteriostatic.
Adverse effects associatedwith sulfonamides includeallergic reactions, type IIand III hypersensitivity,hypothyroidism (withprolonged therapy),keratoconjunctivitis sicca,and skin reactions.
Usually, sulfonamides arecombined withtrimethoprim orormetoprim in 5:1 ratio toproduce a synergisticeffect.
500 mg tablets andtrimethoprim +sulfadiazineavailable as 30, 120,240, 480 and960 mg tablets(although availabilityis limited).
100 mg/kg IV, po (loadingdose), followed by50 mg/kg q12h IV, po (seeTrimethoprim +sulfadiazine section foradditional dosing).
Sulfasalazine (sulfapyri-dine + mesalamine)(Azulfidine [Salazopyrinin Canada])Sulfonamide +antiinflammatory drug.Used for treatment ofcolitis. Sulfonamide haslittle effect, salicylic acid(mesalamine) hasantiinflammatory effects.Adverse effects are allattributed to sulfonamidecomponent.Keratoconjunctivitis siccahas been reported.Usually used for treatmentof idiopathic colitis, oftenin combination withdietary therapy.500 mg tablets.Dog: 10–30 mg/kgq8–12h po.Cat: 20 mg/kg q12h po.Tepoxalin (Zubrin)Analgesic drug andNSAID. Used to treat painand inflammation in dogs,particularly osteoarthritis.Tepoxalin haslipoxygenase-inhibitingeffects (decreasesleukotrienes), and theactive metabolite hascyclooxygenase-inhibitingeffects (decreasesprostaglandins), which islonger acting.Most common adverseeffects from the clinicaltrials have been GI related(nausea, vomiting,diarrhea).When switching animalsfrom another NSAID orcorticosteroid totepoxalin, allow 7-daywashout. Long-termsafety of tepoxalin has notbeen established in cats.50, 100, and200 mg tablets(Zydis freeze-driedtablet).Dog: 10–20 mg/kg poinitially, 10 mg/kg q24hpo thereafter.Cat: safe dose notestablished.(continued)