Small Animal Dermatology, 3rd edition

APPENDIX B DRUG FORMULARY 807

Primor (ormetoprim +sulfadimethoxine)

Antibacterial drug.Ormetoprim inhibitsbacterial dihydrofolatereductase, sulfonamidecompetes withp-aminobenzoic acid(PABA) for synthesis ofnucleic acids.Bactericidal/bacteriostatic.Broad antibacterialspectrum and activeagainst some coccidia.

Several adverse effectshave been reported fromsulfonamides.Ormetoprim has beenassociated with CNSadverse effects.

Doses listed are based onmanufacturer’srecommendations.Controlled trials havedemonstrated efficacy fortreatment of pyodermaon once-daily schedule.

Combination tablet(ormetoprim +sulfadimethoxine).

27mg/kgonfirstday,followed by 13.5 mg/kgq24h po.

Progesterone, repositol See Medroxyprogesterone

acetate.

Propylthiouracil (PTU)(generic,Propyl-Thyracil)

Antithyroid drug.Compared tomethimizole, PTU inhibitsconversion of T

4

to T

. 3

Adverse effects in catsinclude hemolytic anemia,thrombocytopenia, andother signs ofimmune-mediateddisease.

Use of PTU in most catshas been replaced withmethimazole.

50 and 100 mgtablets.

11 mg/kg q12h po.

Ranitidinehydrochloride (Zantac)

Histamine H2 antagonist.Same as cimetidine except4–10

×

more potent and

longer acting.

Ranitidine may have fewereffects on endocrinefunction and druginteractions, compared tocimetidine.

Pharmacokineticinformation in dogssuggests that ranitidinemay be administered lessoften than cimetidine toachieve continuoussuppression of stomachacid secretion. Ranitidinemay stimulate stomachemptying and colonmotility viaanticholinesterase action.

75, 150, 300 mgtablets; 150,300 mg capsules;25 mg/mL injection.

Dog: 2 mg/kg q8h IV, po.Cat: 2.5 mg/kg q12h IV;3.5 mg/kg q12h po.

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