Paracetamol (acetaminophen) plays a unique role in children because it is the first-line treatment for both fever and pain. When administered at the recommended doses, it has little negative effects and is very well tolerated. While fever alone does not require treatment, when combined with discomfort or pain, paracetamol provides relief. Paracetamol is also useful for mild to severe pain, either alone or in conjunction with another medication. Even in extreme pain, paracetamol has a strong additional analgesic impact to opioids. The paediatric dose ranges between 10 and 15 mg/kg worldwide.

Paracetamol has a relatively short half-life of 2-2.5 hours and is highly lipid-soluble. Paracetamol is rapidly absorbed across the duodenal mucosa and into the bloodstream after oral administration, where it is primarily metabolised by the liver. Paracetamol is mostly metabolised by glucuronidation and sulphation, with hepatotoxicity caused by a small pathway involving the CYP2E1 enzyme. The glucuronidation and sulphation routes are present in children, but their contributions to paracetamol metabolism vary until the glucuronidation pathway matures, which happens around the age of two years.

The concentration of paracetamol in the brain determines its analgesic effects. Paracetamol plasma levels must therefore be high enough to allow the medication to pass the blood brain barrier and accumulate in neuronal tissue at therapeutic levels. Paracetamol requires at least 15 mg/kg orally to generate effective analgesia, with four-hour dosage swiftly approaching steady-state therapeutic concentrations. A single loading dose of paracetamol, such as 30 mg/kg, will alter the pharmacokinetics towards the desired steady-state.

Obese children should be dosed with paracetamol using the same mg/kg approach as adults, taking care not to exceed the adult dose. This is due to the fact that lipid-soluble paracetamol is distributed uniformly throughout the body. If doses are reduced for children who weigh more than their optimal body weight, they risk being under-dosed and not receiving appropriate pain relief.

New Dosing Instructions For Children’s Liquid Paracetamol Products

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