Manufacturer to warn of fatal adverse reactions from blood-clotting drug and anaesthetic mix-ups

In a letter to healthcare professionals, drugs manufacturer Pfizer is to warn of serious and fatal adverse reactions following inadvertent administration of tranexamic acid instead of local anaesthetics.

The letter, seen by The Pharmaceutical Journal and dated 30 April 2026, says: “Serious, including fatal, adverse reactions have been reported after inadvertent intrathecal administration [of tranexamic acid] due to mix-ups, mostly with injectable local anaesthetics.”

Pfizer said it was sending the letter on behalf of marketing authorisation holders and in agreement with the Medicines and Healthcare products Regulatory Agency (MHRA).

Tranexamic acid is an antifibrinolytic, used in the prevention and treatment of haemorrhages.

“Intrathecal, epidural, intraventricular and intracerebral use of tranexamic acid solution for injection is contraindicated,” the letter added.

“Cases of medication errors have been identified, including cases reported in the EU, where tranexamic acid injection was inadvertently administered intrathecally or epidurally.

“Most of these cases involved mix-ups of vials or ampoules resulting in erroneous administration of tranexamic acid instead of the intended injectable local anaesthetic (e.g. bupivacaine, levobupivacaine, prilocaine).”

It has added that, when administered intrathecally, serious patient harms had been reported, including prolonged hospitalisation and death, while serious adverse reactions that were reported include severe back, gluteal and lower limb pain, myoclonus, generalised seizures and cardiac arrhythmias.

“Extreme caution should be taken when storing, handling and administering IV formulations of tranexamic acid to ensure the correct route of administration. This includes clearly labelling syringes containing tranexamic acid for IV use only and storing tranexamic acid injectables separately from injectable local anaesthetics,” it added.

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Source: The Pharmaceutical Journal, 14 April 2026