Methimazole is one of the best medications for feline transdermal application. Recent studies have shown methimazole to be especially effective in the treatment of cats with hyperthroidism. The medication has allowed many cats with hyperthyroidism to be treated when other routes of administration have been exhausted. The molecular properties of methimazole allow it to be absorbed easily through the skin, and the presence of a simple diagnostic test lets you know if the prescribed dose is effective or if it needs titrated.
1. The Molecular Properties of Transdermal Methimazole
Molecules are best absorbed transdermally when they have a molecular weight of less than 400g/mol. Methimazole is significantly below that goal weight at 114.17g/mol – meaning that methimazole is easily and fully absorbed through the skin.
Methimazole has a melting point of 146°C. Ideal transdermal medications have a melting point below 200°C, which places methimazole squarely into the “ideal” transdermal medications grouping. Methimazole is more hydrophilic than lipophilic, however, using the correct transdermal base allows methimazole to be absorbed into the patient’s systemic circulation. Check with your compounding pharmacist for more information on the compatibility of methimazole with your preferred transdermal base.
2. Diagnostic Tests Can Monitor Efficacy
With some medications it is difficult to tell if they are working effectively. Cats are not able to tell their caregivers or veterinarians if a medication is working, so having a diagnostic test to confirm a medication’s efficacy is beneficial. Every 2 to 4 weeks after transdermal methimazole treatment begins, you should draw a T4 level on your patient. The methimazole dose can then be increased, decreased, or remain the same to maintain T4 levels within normal limits.
3. Transdermal Methimazole Works!
Transdermal therapy has fewer gastrointestinal side effects than oral methimazole because it absorbs directly into the bloodstream rather than passing through the stomach. This will help keep your patient – and their caregiver! – more comfortable.
Multiple studies have demonstrated that transdermal methimazole is a viable option for felines with hyperthyroidism. Transdermal methimazole may take a few weeks longer to achieve a euthyroid state compared to oral treatment, but in felines where oral dosing is not an option, the extra time it takes to reach therapeutic levels is not an issue. The longer a treatment takes to work, the more likely non-compliance on the part of your patients’ caregiver becomes, so be sure to schedule follow-up appointments and explain the necessity of continuous dosage to the pet owner.Watch Full Movie Online Streaming and Download
The molecular properties of the drug, as well as the presence of a diagnostic test for efficacy, make methimazole an ideal transdermal drug. This information, combined with the studies that have been performed proving its efficacy, make transdermal methimazole a more than viable option for treating hyperthyroidism in felines.
If oral treatment has failed in your feline patient, contact EPC for your compounded transdermal methimazole options. Our on-staff veterinarian will help educate you on the proper prescription and application of transdermal methimazole.
– Bryce Walker, Veterinary Compounding Pharmacy Student under the direction of Drew Olson, DVM, Veterinary Division – National Director