Medicines

Methotrexate error warning


Rheumatologists need to do more to teach the broader medical profession about the safe use of methotrexate, a leading rheumatologist says in light of new safety warnings.

Dr David Liew, a consultant rheumatologist and clinical pharmacology fellow at Austin Health in Melbourne, has rejected a coroner’s call for tighter restrictions on methotrexate prescribing but says greater awareness is needed across the profession on safely prescribing the immunosuppressant.

It comes after a Victorian coroner called for the introduction of authority prescribing to discourage GPs from initiating the drug, following the death of an elderly man whose GP initiated him on a high daily dose for psoriasis without performing blood tests.

At the same time, the TGA has issued another warning over the dangers of methotrexate misadventure, detailing 28 cases in which patients took incorrect doses, in some cases causing their deaths.

The cases up to March 2018 logged on the medicine watchdog’s adverse events database, show the most common error involved patients taking methotrexate daily, causing adverse effects including thrombocytopenia, stomatitis, mucosal inflammation and gastrointestinal effects.

Other reported reasons for errors included patients confusing the medicine with another that was co-prescribed (such as folic acid) communication problems for those from non-English speaking backgrounds, and pharmacist dispensing, and administration or instructions given by health professionals.

Dr Liew said the TGA figures were likely just the tip of the iceberg given of adverse events are grossly underreported.

But it was also not surprising, because despite the drug being used in Australia for many years, it involves a relatively complicated regimen for many patients.

In its Medicines Safety Update the TGA announced it was working with the methotrexate manufacturer on new warnings for cartons, stating “caution: usual dose is once weekly” and stronger warnings in product information.

The TGA also advises prescribers to and pharmacists to relay these messages to patients.

Dr Liew said the regulatory approach was an important foundation to the safe approach of the drug as a mandated minimum standard.

“But I think all rheumatologists know we need to do more than that, and I think we want to make sure everyone else in the medical sphere is aware that methotrexate is a drug that needs to be taken seriously,” he told the limbic.

“I think we need to work better on communication, that came through in the TGA report, most of the problems come through in communication and the number of people around the country who have been working on more standardised methotrexate introduction plans, like what’s come out of Brisbane, is fairly clear, and I think we need to try and adopt that on a broader scale.

“While we expect our GP colleagues to help us co-manage methotrexate, at the same time we don’t have a standardised way as a specialty of communicating with them about that.”

He also warned against a heavy-handed approach, such as a recommendation by the Victorian coroner to introduce authority prescribing for methotrexate in a bid to discourage busy GPs from prescribing it.

Dr Liew said while the blanket rule was that GPs should not initiate methotrexate, they could safely do so in collaboration with a specialist who was familiar with the drug and in the context of their particular patient.

Any regulatory approach that curtailed this capacity could disadvantage rural patients, leaving them unable to start methotrexate in a timely manner.

“I don’t think we can rely on regulation to safeguard us against everything, so on that basis I don’t think I can support that suggestion in its current form,” Dr Liew told the limbic.

“I do think we need to improve education around methotrexate and it needs to be clear that it’s not acceptable for GPs to initiate without discussion with a specialist who is familiar with its use.”

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