Bigger doses of penicillin needed for today’s bigger children

Penicillin doses for children need to be reviewed to take account of the fact youngsters are getting heavier meaning they may not be getting an adequate dose doctors have said.Bigger doses of penicillin needed for today's bigger childrenDosing guidelines have remained unchanged for almost 50 years and are mostly based on children’s ages.

But experts argue that the dose a child needs is determined by their weight – and the average weight of children has increased.

It means that children may not be receiving a big enough dose of antibiotics to combat their infection.

Giving inadequate doses also encourages bacteria to become resistant to antibiotics making them harder to treat in future, it was warned.

The average weight today of a five-year-old is 21kg and a 37kg for a 10-year-old – up to 20% higher than in 1963, researchers at King’s College London sad.

The study, led by a team at King’s College London and St George’s, University of London, said they were “surprised at the lack of recent evidence” to support current dosing recommendations for penicillins.

Writing in the British Medical Journal (BMJ), they said ‘fractions’ of adult doses are calculated instead of basing the dose on the weight of the child who needs treatment.

The article said: “The widely used doses are still based on the original dosing principle of a big child = half an adult, small child = half a big child, baby half a small child.”

The team analysed the actual dose that would be received today based on age bands recommended in the 2010/11 British National Formulary for Children and the current weights of children based on 2009 Health Survey for England data.

The results showed doses could be strikingly low.

The authors also pointed out that many infections do not need treatment with antibiotics.

“Many of the five million children in England who receive oral penicillins each year may not need them, but those who do should receive them in an effective dose.”

Dr Paul Long, senior lecturer in pharmacognosy at King’s College London, said: “We were surprised at the lack of evidence to support the current oral penicillins dosing recommendations for children, as it is such a commonly used drug.

“Children’s average size and weight are slowly but significantly changing, so what may have been adequate doses of penicillin 50 years ago are potentially not enough today.

“It is important to point out that this study does not provide any clinical evidence that children are receiving suboptimal penicillin doses that lead to harm, and we want to reassure parents of that.

“But what we are saying is that we should ensure that children with severe infections who need these antibiotics the most are still receiving an effective dose.”

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