Information for Australian doctors and patients about commonly used thyroid medications is out of date and could lead to harmful misuse of the drugs, a senior endocrinologist has warned.
Professor of Medicine Jim Stockigt, of Monash University and The Alfred and Epworth Hospitals in Melbourne, reviewed product information (PI) for thyroid medications published in pharmaceuticals guidebooks and endorsed by the Therapeutic Goods Administration (TGA).
Prof Stockigt found numerous discrepancies when he compared the information with current medical literature and Australasian and international reviews of evidence.
"The quality of information on thyroid-related medications in the PI of each drug ... is deficient to an extent that requires prompt review," Prof Stockigt said in the latest issue of the Medical Journal of Australia.
"If such recommendations for the use of thyroid-related medications, as espoused in the PI, ... were mistakenly interpreted as firm guidelines for prescribing practice, these texts would legitimise potential misuse of medication."
PI for the two anti-thyroid drugs, carbimazole and propylthiouracil - for which about 80,000 prescriptions are filled in Australia every year - has not been updated significantly since 1985, although there have been important advances in treatment strategies since then.
About 700,000 prescriptions are filled annually for thyroxine, used to correct thyroid hormone deficiency. PI for that drug is out-of-line with current practice in many important details, particularly for commencement of treatment and in relation to pregnancy.
Currently, a drug's manufacturer or sponsor is responsible for keeping PI up to date - a situation Australian Prescriber editor Dr John Dowden said may not guarantee timely and accurate revisions.
In an editorial in the same issue of the MJA, Dr Dowden suggested a 'use-by date' for PI.
"Drugs have an expiry date, so why not extend the concept to product information? This would require a date to be set for a comprehensive check of the product information," he said.
The TGA should be able to recoup its costs from manufacturers, Dr Dowden said.