This work was performed at IVABS, Massey University, Palmerston North, New Zealand. This work was presented as a poster at the 2009 ACVIM Forum/Canadian VMA convention, Montreal, Canada.
The Efficacy and Safety of a Novel Lipophilic Formulation of Methimazole for the Once Daily Transdermal Treatment of Cats with Hyperthyroidism
Article first published online: 28 SEP 2011
Copyright © 2011 by the American College of Veterinary Internal Medicine
Journal of Veterinary Internal Medicine
Volume 25, Issue 6, pages 1357–1365, November-December 2011
Total views since publication: 38
How to Cite
Hill, K.E., Gieseg, M.A., Kingsbury, D., Lopez-Villalobos, N., Bridges, J. and Chambers, P. (2011), The Efficacy and Safety of a Novel Lipophilic Formulation of Methimazole for the Once Daily Transdermal Treatment of Cats with Hyperthyroidism. Journal of Veterinary Internal Medicine, 25: 1357–1365. doi: 10.1111/j.1939-1676.2011.00799.x
- Issue published online: 16 NOV 2011
- Article first published online: 28 SEP 2011
- Manuscript Accepted: 12 AUG 2011
- Manuscript Revised: 31 JUL 2011
- Manuscript Received: 10 MAY 2011
- Bomac Laboratories Ltd
Previous studies on transdermal methimazole have used pluronic lecithin organogel as the vehicle. This might not be the most suitable vehicle for a lipophilic drug, such as methimazole.
Once daily transdermal administration of a novel lipophilic formulation of methimazole is as safe and effective as oral carbimazole in treating hyperthyroidism in cats.
Forty-five client-owned cats diagnosed with hyperthyroidism.
Prospective study. Cats with newly diagnosed, untreated hyperthyroidism were treated with carbimazole (5 mg PO, q12h) or methimazole (10 mg) applied to the inner pinnae q24h. Cats were examined after 0, 1, 4, 8, and 12 weeks of treatment. Clinical signs, body weight, systolic blood pressure, hematologic, serum biochemical and urine parameters, total serum thyroxine concentrations (TT4), and serum methimazole concentrations were recorded.
No significant differences between groups were detected at day 0. Both formulations were effective in treating hyperthyroidism. No significant differences were detected in thyroxine concentrations, body weight, blood pressure, heart rate, alkaline phosphatase, alanine aminotransferase, creatinine, urea, and urine specific gravity (USG) between groups. The serum methimazole concentrations correlated poorly with TT4-concentrations in both groups.
Conclusions and Clinical Importance
In this 12-week trial, once daily application of a novel formulation of transdermal methimazole applied to the pinnae was as effective and safe as twice daily oral carbimazole in the treatment of cats with hyperthyroidism. This novel formulation and transdermal application could have practical advantages to some pet owners.