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Koalas are accident-prone marsupials. Many of them live in the wild and are therefore at risk of injury from cars, forest fires and animal attacks.1 Previous investigators have tried many different ways to aid the healing process, including the use of fentanyl, meloxicam and tramadol.1
A group of researchers in Australia recently studied the use of paracetamol tablets (known as acetaminophen in some parts of the world) in koalas. Although koalas have been given paracetamol and codeine orally for many years, analysis of the actual kinetics of paracetamol alone in koalas has been limited.
Koalas are about 60 to 90 cm tall and can weigh between 4 and 13 kg (9-29 pounds).2 The researchers administered an oral dose of 15 mg/kg twice daily to 8 adult koalas at Taronga Zoo in New South Wales and then looked for significant changes in the koala’s haematology, plasma electrolytes and biochemical analytes. The researchers then chose a dose of 15 mg/kg based on previous recommendations in a textbook commonly used in Australia.1
Paracetamol is toxic to many other animal species, such as cats and dogs, because their metabolism breaks the drug down into toxic metabolites. However, according to the results of this recent study, koalas have the necessary enzymes to safely absorb and metabolise paracetamol.1
The dose studied, 15 mg/kg administered twice daily, achieved the therapeutic plasma concentration needed to provide mild to moderate pain relief in humans, but may not be the answer for koalas. The researchers found that lower amounts of the drug are present in koalas’ bodies due to protein binding. This means that the chosen dosage range may need to be increased for koalas to feel the same effects of the drug as humans.1
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Christina Nault is a 2025 PharmD candidate studying veterinary pharmacy at the University of Connecticut in Storrs.
References
- Govendir M, Vogelnest L, Shapiro AJ, Marschner C, Kimble B. Pharmacokinetic profile of oral and subcutaneous administration of paracetamol in the koala (Phascolarctos cinereus) and prediction of its analgesic efficacy. PLoS ONE. April 17, 2024. Retrieved August 9, 2024. https://doi.org/10.1371/journal.pone.0300703
- 2.Nature. Koala Fact Sheet. PBS. July 1, 2020. Accessed August 9, 2024. https://www.pbs.org/wnet/nature/blog/koala-fact-sheet/#:~:text=Size%20and%20Weight%3A
