Shortage of diabetes medicine raises larger questions

Matt Woodley

18/05/2020 3:31:33 PM

There are concerns over a TGA notice that allows pharmacists to substitute metformin XR 500 mg without consulting the prescriber.

Pharmacist choosing pills
The metformin shortage is expected to last until at least 5 June, with some brands likely to be unavailable until December.


The ‘serious shortage’ of metformin XR (extended release) 500 mg was announced last week via a notice on the Therapeutic Goods Administration (TGA) website.
In order to reduce the impact of the shortage, the TGA’s notice states pharmacists are able to substitute metformin XR 500 mg with either immediate-release metformin 500 mg or metformin XR 1000 mg, depending on the prescribed dose.
However, Dr Gary Deed, Chair of the RACGP Specific Interests Diabetes network, told newsGP the TGA did not make enough effort to inform GPs and other prescribers.
‘Passive communication is not optimal; no GP reads the TGA website and substitution without prescriber knowledge leaves gaps in continuity of care,’ he said.
‘Who takes responsibility for errors that could have been avoided?
‘My concern is that [without] an agreed communication strategy, many GPs would remain unaware of these changes and not manage this issue proactively for the best interest of their patients.’

When questioned how GPs were informed of the shortage, a TGA spokesperson pointed to the notice on the administration’s website and initially said health professional groups, including the RACGP, had been informed in advance of its publication, before later conceding it did not email the college until the next day.
‘The substitution notice was published on Wednesday evening last week [13 May]. The notice was discussed prior to publication at the Medicine Shortages Working Party meeting which includes health professional groups,’ the spokesperson said.
‘However, the TGA wants to clarify the RACGP was notified of the substitution notice by email on Thursday morning [14 May].’
The spokesperson also said the scope of substitution is ‘limited’ and safety issues should not be expected if the substitution occurs ‘in accordance with the protocol’.
‘The legal standing of the notice is given through state and territory laws over pharmacy practice and so pharmacists would need to meet these requirements,’ the spokesperson said, before adding that ‘professional practice matters’ are an issue for the Australian Health Practitioner Regulation Agency.
Despite the assurances, Dr Deed said the ‘concerning’ lack of communication has the potential to increase patient confusion and could lead to a possible loss of adherence and persistence to usual regimens, threatening clinical outcomes.
He is also concerned that the notice allows pharmacists to use their ‘professional and clinical judgement’ to determine whether it is suitable to substitute a patient’s prescribed medicine.
The TGA spokesperson told newsGP patients must consent to the substitution and that pharmacists ‘should’ notify the prescriber of the substitution ‘as soon as possible’.
The metformin XR 500 mg shortage is expected to last until at least 5 June, although some brands may not be available until December.
‘Some sponsors have cited manufacturing issues as the reason for the shortage and details, including timeframes, may be updated by the sponsor at any time,’ the TGA spokesperson said.
According to the TGA notice, patients ‘previously intolerant to metformin immediate-release formulations’ must be referred to the prescriber if the relevant substitution includes immediate-release metformin. But Dr Deed believes this advice is also flawed.
‘How do patients even know this was why they had been started on metformin XR [and] how certain will a pharmacist be before just substituting it?’ he said
‘GPs often hold this information embedded in clinical records, so ideally it is the GP that should be final arbiter of this substitution.
‘Though the risks might be considered small, they are not fully covered by this instruction from the TGA.’
As such, Dr Deed believes it is important for GPs to be aware of the shortage as it could see patients receive different strengths and/or tablet numbers to their usually prescribed metformin, while advice on the timing of dosing may also change at the pharmacist dispensing level.
‘The concern is that the use of the 500 mg XR form may have been for bowel-related side-effects from the non-XR form – thus the immediate release substitution may not always be optimal in many cases,’ he said.
‘My advice is to do an immediate database search on any prescribed metformin XR 500 mg and identify those patients and proactively arrange a telehealth or face-to-face appointment to advise them of these potential changes.
‘I would also review current medication – can a fixed dose combination, such as metformin with the DDP4 inhibitors or SGLT2 inhibitors, be considered?
‘If the patient has persistently elevated HbA1c despite the metformin XR 500 mg, it may be an ideal time to increase to 1000 mg XR, which is still available, to help manage the glycaemic variability and, alternatively reinforce lifestyle and weight-loss options to consider whether a break off the metformin is possible as well?’
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Dr Penny Lisa Wood   19/05/2020 9:20:57 AM

What GPs really need is a centralised database of drug shortages connected to our practice management software. Then whenever we go to re-precribe something in extended short supply, we'd get notified, and prompted to substitute.

Ideally when the shortage ended the software would then prompt us to return to the prior script.

This is all quite achievable with a little political will.

Dr Nirmala Ben Patel   19/05/2020 11:55:43 AM

whole heartedly agree with Dr Wood-