The head of medical affairs at GlaxoSmithKline New Zealand, Andrew Hvizdos, has responded to questions from NBR regarding reported severe reactions to a reformulated version of a potentially lifesaving drug they produce - Eltroxin.
Can you tell us how many people to date have had an adverse reaction?
Medsafe has recently stated that around 600 events have been reported. The majority of the 70,000 patients in NZ have transferred to the new formulations successfully. Patient safety with our medicines is our first priority at GSK so we share the frustration of some patients in NZ of feeling unwell when extensive testing and retesting by GSK has shown that the tablets should be safe and effective when used as prescribed.
Have there been adverse reactions in any other markets the drug is sold?
We have seen a very small increase in adverse event reports in a small proportion of the other markets receiving the new formulation and no increase in the others. We have not seen the same trend anywhere else as in New Zealand.
Why the reformulation?
GSK has consolidated the manufacturing locations for Eltroxin tablets. Changes in formulation are fairly common as the technology used to produce a medicine evolves and GSK’s manufacturing processes evolve to reflect this. Eltroxin requires a specialised manufacturing process and GSK is reviewing its manufacturing locations in light of this.
Apparently animals given the drug are also exhibiting adverse reactions?
Eltroxin is not registered for use in animals so we are unable to provide any guidance in this area. We suggest owners speak to their vet about any concerns.
What procedures are under way to determine the cause of these reactions?
We are concerned that some patients have been experiencing symptoms which are difficult to explain but causing them to worry. It is important that patients with any concern about their medication should make an appointment with their doctor as soon as possible to investigate the cause of the symptoms.
An increase in adverse event reports is not uncommon when patients are placed on a new or reformulated product. It is important to establish whether an adverse event report is related to the medicine itself or to other factors such as dosing or interaction with other medications.
The challenge in interpreting the adverse event reports received from patients is that:
Symptoms may relate to other causes such as incorrect dosing, interaction with other medications taken by a patient and symptoms from a thyroid disorder itself or other health issues a patient may have.
An increase in public awareness often leads to an increase in reports so it is important to establish if the report is specifically related to the patient’s medicine or if the concern raised by public awareness has caused patients to attribute existing, unrelated symptoms to their medication.
A small number of patients will be unable to tolerate any given medication. Usually those patients would be prescribed an alternative treatment. No alternative is presently available in NZ but we understand Pharmac is actively looking for a new supplier.
Whenever someone’s thyroid medicine is changed, it is important that they are closely monitored by their doctor to be sure there is no change in their condition. If they are experiencing symptoms, it will be important that their doctor repeats their thyroid function blood tests to determine if their levels have changed and their dosage needs to be adjusted. Any change in dosage could take up to 6 weeks to see the full effect of the change.
For more information on how thyroid patients should be monitored following any change to their thyroid medicine, including information on the Eltroxin tablet changes, please go here.
GSK is determined to get to the bottom of this issue and is working with Medsafe to decide the best course of action.