title: Efficacy and safety of once versus twice daily administration of methimazole in cats with hyperthyroidism.
abstract: OBJECTIVE
  To determine whether once daily administration of methimazole was as effective and safe as twice daily administration in cats with hyperthyroidism.
  
  
  METHODS
  Randomized, nonblinded, clinical trial.
  
  
  METHODS
  40 cats with newly diagnosed hyperthyroidism.
  
  
  METHODS
  Cats were randomly assigned to receive 5 mg of methimazole, PO, once daily (n = 25) or 2.5 mg of methimazole, PO, twice daily (15). A complete physical examination, including measurement of body weight; CBC; serum biochemical analyses, including measurement of serum thyroxine concentration; and urinalysis were performed, and blood pressure was measured before and 2 and 4 weeks after initiation of treatment.
  
  
  RESULTS
  Serum thyroxine concentration was significantly higher in cats given methimazole once daily, compared with cats given methimazole twice daily, 2 weeks (3.7 vs 2.0 micro +/- g/dL) and 4 weeks (3.2 vs 1.7 microg/dL) after initiation of treatment. In addition, the proportion of cats that were euthyroid after 2 weeks of treatment was lower for cats receiving methimazole once daily (54%) than for cats receiving methimazole twice daily (87%). Percentages of cats with adverse effects (primarily gastrointestinal tract upset and facial pruritus) were not significantly different between groups.
  
  
  CONCLUSIONS
  Results suggest that once daily administration of methimazole was not as effective as twice daily administration in cats with hyperthyroidism and cannot be recommended for routine use.
authors.affiliation: Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Lauren A
authors.initials: LA
authors.lastname: Trepanier
authors.forename: Stacey B
authors.initials: SB
authors.lastname: Hoffman
authors.forename: Mandy
authors.initials: M
authors.lastname: Kroll
authors.forename: Ilona
authors.initials: I
authors.lastname: Rodan
authors.forename: Laura
authors.initials: L
authors.lastname: Challoner
mesh_terms: D000284:Administration, Oral; D000818:Animals; D013956:Antithyroid Agents / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D002371:Cat Diseases / Q000188:drug therapy*; D002415:Cats; D004334:Drug Administration Schedule / Q000662:veterinary; D006980:Hyperthyroidism / Q000188:drug therapy / Q000662:veterinary*; D008713:Methimazole / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use; D012449:Safety; D013974:Thyroxine / Q000097:blood; D016896:Treatment Outcome
chemical_list: D013956:Antithyroid Agents; D008713:Methimazole; D013974:Thyroxine