February 2022 sees two additional levothyroxine medicines introduced to the PBS:1
- levothyroxine Eltroxin 125 micrograms (µg) tablet: new item listing
- levothyroxine (added to the existing listings of the Eutroxsig and Oroxine brands):
- Eltroxin 50, 75, 100 and 200 µg tablets
- Levoxine 50, 75, 100 and 200 µg tablets.
See the PBS Schedule for complete details of each PBS listing described in this article.
Two new brands of levothyroxine (Eltroxin and Levoxine) that do not need to be stored in a refrigerator3,4 are now listed on the PBS General Schedule (Section 85) as Unrestricted Benefit listings together with the Eutroxsig and Oroxine brands.1 See Table 1.
With the addition of the two new brands, the PBS listings for levothyroxine 50, 75, 100 and 200 µg tablets:1
- are now ‘a’ flagged for the Eutroxsig, Levoxine and Oroxine brands.
- state that Eltroxin is not interchangeable with the equivalent strengths of the other three levothyroxine brands (Eutroxsig, Levoxine and Oroxine) on a dose-to-dose basis and dose titration (adjustment)3,5 may be required.
See ‘What else should health professionals know?’ below for information about bioequivalence, ‘a’ flagging and dose titration (adjustment).
Eltroxin 125 µg tablet is the only brand listed on the PBS for this strength of levothyroxine.1
Table 1: Levothyroxine medicines listed on the PBSa,b and their storage temperatures1,3,4,6,7
Tablet strengths (µg)
a Unrestricted Benefit listings1
b Can be prescribed by nurse practitioners for continuing therapy where prescribing of the medicine for a patient has been initiated by a medical practitioner1
What is it?
Levothyroxine is a naturally occurring thyroid hormone.8 Its principal pharmacological effect is to increase the metabolic rate of body tissues. It is also involved in the regulation of cell growth and differentiation.3,4
Who is it for?
Levothyroxine is indicated for replacement therapy9 in the management of demonstrated thyroid hormone deficiency,3,4 which includes:8,10
- overt primary hypothyroidism
- subclinical primary hypothyroidism (also called mild thyroid failure)
- secondary (central) hypothyroidism.
It is also indicated for the suppression of thyroid stimulating hormone (TSH) in the management of TSH-responsive tumours of the thyroid.3,4
What else should health professionals know?
The aim of levothyroxine replacement therapy is to achieve euthyroidism and relieve hypothyroid symptoms.10 Suppression therapy is recommended for thyroid cancer to suppress TSH below normal range and for euthyroid goitre, where the aim is to achieve goitre regression.9
For adults, the initial daily dose of levothyroxine is 12.5–100 μg daily, depending on the patient’s age, frailty and type of hypothyroidism.3,5,10 The dose is increased at 4-8-week intervals up to a maximum of 100– 200 µg daily.3-5,10
Wherever possible, whole tablets should be taken (eg, if the dose required is 150 µg, then a 1 x 100 µg tablet and 1 x 50 µg tablet should be taken, rather than 1½ x 100 µg tablets).3,4 The Eltroxin 125 µg tablet enables a single tablet to be taken, rather than a 1 x 100 µg tablet and 1 x 25 µg tablet.
The Eutroxsig and Oroxine brands of levothyroxine need to be stored in a refrigerator at 2–8°C.6,7
Eltroxin and Levoxine do not need to be stored in a refrigerator. They should be stored at below 25°C in the original container and be protected from light and moisture.3,4
Bioequivalence, ‘a’ flagging and dose titration (adjustment)
Eutroxsig and Oroxine are the same formulation of levothyroxine, marketed under different brands.8
The formulation of Eltroxin has a lower dissolution and is more stable than Eutroxsig and Oroxine. These differences enable Eltroxin to be stored below 25°C without refrigeration. But at the same time they cause Eltroxin not to be bioequivalent to the other two brands.8
The formulation of Levoxine enables it to be stored below 25°C without refrigeration, and without impacting on bioequivalence with the Eutroxsig and Oroxine formulation.4,11 As a result, Eutroxsig, Levoxine and Oroxine are ‘a’ flagged on the PBS.1
When switching to or from Eltroxin, it is recommended to check serum TSH and, if necessary, adjust the dosage to achieve euthyroidism and relieve hypothyroid symptoms.5,12 The check should be made 6 weeks after a change of formulation due to the long half-life of levothyroxine.13
'a' flagging on the PBS
The practice of ‘a’ flagging in the Schedule of Pharmaceutical Benefits denotes that:14
- brand substitution may be undertaken by pharmacists at the point of dispensing without difference in clinical effect or health outcomes
- brand substitution by pharmacists is permitted without reference to the prescriber when the following conditions apply:
- the patient agrees to the substitution; and
- the prescriber has not indicated on the prescription form that substitution should not occur by ticking the box labelled ‘brand substitution not permitted’.
Extreme caution is required when prescribing levothyroxine for patients with cardiovascular disorders due to the risk of worsening ischaemic symptoms such as angina and arrhythmias. Dosage should be lowered if these adverse effects occur.3-5
Caution is also required for patients with hypothyroidism and diabetes, who may require an adjustment of insulin or antidiabetic medicine dosage when beginning treatment. Careful monitoring is recommended when adjusting doses.3-5
Information for patients
- There are four brands of medicines with the active ingredient levothyroxine. They are Eutroxsig, Oroxine, Levoxine and Eltroxin.
- Do not change your brand of levothyroxine medicine unless your doctor or nurse has spoken with you about this. If you change brands you may need to have blood tests. These tests help the doctor work out how much of new brand you need to take.3,4
- Keep Eutroxsig or Oroxine pills in the fridge (not the freezer section). Keep the pills in their blister packs until you need to take them.
- A strip of Eutroxsig or Oroxine pills can stay out of the fridge (below 25°C) for up to 14 days. Do not use pills that have been out of the fridge for more than 14 days. 6,7
- Eltroxin and Levoxine pills do not need to stay in a fridge. Keep them in their original carton. Keep them away from moisture and sunlight.3,4
- Take the pills with some water. Do not chew them.
- These medicines work best if you take them without any food in your stomach. This can be in the morning, 30–60 minutes before breakfast. Or it can be at bedtime, at least 3 hours after your last meal. Try to take your pills the same way each day.3-7
- You may need to take some medicines at a different time to your levothyroxine. Ask you doctor, nurse or pharmacist to help you plan how to take all your medicines.3-7
- Keep your medicines in a locked cupboard off the ground. Keep them away from children and animals. Do not let other people take your medicines.
- Keep a list of all the medicines you take, including natural medicines, vitamins and minerals.
- NPS MedicineWise Managing thyroid conditions in primary care: Finding a balance between when to test, what to test and how to treat.
This program includes information and resources for health professionals, including a Thyroid testing algorithm for general practice, and also for consumers.
- Pharmaceutical Benefits Scheme. Schedule of Pharmaceutical Benefits (Summary of changes). Canberra: Australian Government Department of Health, February 2022 (accessed 26 January 2022).
- Therapeutic Goods Administration. Updating medicine ingredient names – list of affected ingredients. Canberra: Australian Government Department of Health, 2020 (accessed 3 February 2022).
- Aspen Pharma Pty Ltd. Eltroxin product information. 19 November 2019 (accessed 26 January 2022).
- Sun Pharma ANZ Pty Ltd. Levoxine product information. 29 July 2021 (accessed 27 January 2022).
- Australian Medicines Handbook. Levothyroxine. Adelaide: AMH Pty Ltd, 2022 (accessed 26 January 2022).
- Aspen Pharma Pty Ltd. Eutroxsig product information. 10 July 2019 (accessed 27 January 2022).
- Aspen Pharma Pty Ltd. Oroxine product information. 10 July 2019 (accessed 27 January 2022).
- Therapeutic Goods Administration. Australian public assessment report for thyroxine sodium. Canberra: Australian Government Department of Health, 2014 (accessed 26 January 2022).
- Australian Medicines Handbook. Thyroid hormones. Adelaide: AMH Pty Ltd, 2022 (accessed 26 January 2022).
- Bone and Metabolism Expert Group. Therapeutic Guidelines: Thyroid disorders. West Melbourne: Therapeutic Guidelines, 2019 (accessed 27 January 2022).
- Therapeutic Goods Administration. Prescription medicines: registration of new generic medicines and biosimilar medicines. Canberra: Australian Government Department of Health, 2022 (accessed 28 January 2022).
- Walsh JP. Managing thyroid disease in general practice. Med J Aust 2016;205:179-84.
- New Zealand Medicines and Medical Devices Safety Authority. Eltroxin formulation change – Monitor patients and adjust dosing if necessary. Auckland: New Zealand Department of Health, 2013 (accessed 28 January 2022).
- NPS MedicineWise. Brand equivalence – ‘a’ flagging explained. Sydney: NPS MedicineWise, 2013 (accessed 28 January 2022).