Home' Australian Pharmacist : July 2011 Contents Vol. 30 -- July #07
Continuing Professional Development
• Clinical monitoring is obviously
important as is the measurement of
renal function and T4 simultaneously
during methimazole therapy to
confirm whether the cat's kidneys
can accommodate the level of
glomerular filtration rate associated
with normal thyroid function.6
• For further detailed discussion
regarding the dosing, side effects,
clinical monitoring and other clinical
issues related to methimazole
therapy in feline hyperthyroidism,
see the reviews by Trepanier5,6
Key learning points
• The pharmacist should counsel pet
carers on the correct use of this
product, especially relating to the
use of gloves to prevent exposure
to the methimazole.
• The preparations containing
PLO should not be stored in a
refrigerator and pet carers should
be counselled on the appropriate
storage and to observe for any
1. Which of the following
statement(s) about feline
a) Hyperthyroidism, which is due to
circulation of excessive amounts of
the thyroid hormones T3 and T4, is
less common in cats than in dogs.
b) A value of 4.5 ng/dL of T4 is seen
as diagnostic for hyperthyroidism
in a cat.
c) Methimazole exerts its effect by
preventing the synthesis of the
d) Gastrointestinal symptoms
such as vomiting and diarrhoea
are less likely to occur in the
2. The transdermal route
may be preferable for the
administration of methimazole
to feline patients because:
a) it may result in less improved
adherence by pet carers especially
those who are elderly or impaired.
b) fewer side effects are experienced
by cats with hyperthyroidism.
c) cats are normally not resistant to
administration of an oral daily dose
d) pet carers (when wearing gloves)
are at risk of methimazole
e) all bases available for transdermal
products are greasy and thus
3. Which of the following
statements about pluronic
lecithin organogel (PLO) is
a) PLO is an emulsified system
comprising an oily phase
(poloxamer gel) and an aqueous
phase (lecithin:isopropyl palmitate
b) PLO, although susceptible to
microbial degradation, is also
susceptible to oxidation.
c) Methimazole should be included
into PLO by shear mixing to
allow the formation of micelles
incorporating the drug to enhance
d) PLO contains 22% v/v of
A score of 4 out of 5 attracts 1 CPD credit.
e) Isopropyl palmitate is included
in the PLO base to enhance the
percutaneous absorption of the
4. The preservative contained in
methimazole 5 mg/0.1 mL PLO
a) isopropyl myristate.
b) soy lecithin.
c) sorbic acid.
d) benzoic acid solution.
e) Does not require a preservative.
5. The APPROPRIATE storage
conditions for methimazole 5
mg/0.1 mL PLO gel are:
a) protection from light and air.
b) refrigeration (2--8 ºC).
c) room temperature (< 25 ºC).
changes in appearance of this
product (e.g. phase separation of
• Pharmacists, in consultation
with veterinarians, may decide
on the use of various bases for
methimazole to meet the specific
requirements of the feline patient.
1. Adams HR. Veterinary Pharmacology and Therapeutics.
8th edn. Iowa: Blackwell Publishers; 2001.
2. Merck Veterinary Manual. 9th edn. Hyperthyroidism
[online] [accessed 8 Dec 2010]. At: www.
3. Davidson GS. Understanding Feline Hyperthyroidism.
IJPC. 2003; 7(5):345--7.
4. Behrend EN. Update on drugs used to treat endocrine
diseases in small animals. Vet Clin North Am Small
Anim Pract. 2006; 36(5):1087--105, vii.
5. Trepanier LA. Medical management of hyperthyroidism.
Clin Tech Small Anim Pract. 2006; 21(1):22--8.
6. Trepanier LA. Pharmacologic management of feline
hyperthyroidism. Vet Clin North Am Small Anim Pract.
2007; 37(4):775--88, vii.
7. Martindale: The complete drug reference (electronic
resource). London: Pharmaceutical Press; 2010.
8. Peterson ME, Kintzer PP, Hurvitz AI. Methimazole
treatment of 262 cats with hyperthyroidism. J Vet
Intern Med. 1988; 2(3):150--7.
9. Hoffmann G, Marks SL, Taboada J, et al. Transdermal
methimazole treatment in cats with hyperthyroidism. J
Feline Med Surg. 2003; 5(2):77--82.
10. Sartor LL, Trepanier LA, Kroll MM, et al. Efficacy and
safety of transdermal methimazole in the treatment
of cats with hyperthyroidism. J Vet Intern Med. 2004;
11. Lecuyer M, Prini S, Dunn ME, et al. Clinical efficacy and
safety of transdermal methimazole in the treatment of
feline hyperthyroidism. Can Vet J. 2006; 47(2):131--5.
12. Pignato A, Pankaskie M, Birnie C. Stability of
Methimazole in Poloxamer Lecithin Organogel to
Determine Beyond-Use Date. IJPC. 2010; 14(6):522--5.
13. US Pharmacopeial Convention Inc. US Pharmacopeia
33 -- National formulary 28. USP Monographs:
14. Rowe RC, Sheskey PJ, Quinn ME. Handbook of
pharmaceutical excipients. 6th edn. London:
Pharmaceutical Press; 2009.
15. Mixon W, Helms SR. Transdermal amlodipine besylate
in lipoderm for the treatment of feline hypertension.
IJPC. 2008; 12(5):392--7.
16. Australian Pharmaceutical Formulary and Handbook.
21st edn. Canberra: PSA; 2009.
17. Professional Practice Standards. Version 4.
Compounding. Canberra: PSA; 2010.
18. Australian Medicines Handbook. 10th edn. Adelaide:
solutions through compounding
The articles in this series are independently researched and compiled by PSA commissioned authors and peer reviewed.
Australian Pharmacist acknowledges the unrestricted support from NxGen Wholesaling.
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