London: The obesity epidemic in children could be cutting the effectiveness of penicillin treatment — because the doses were worked out for a slimmer generation.
Guidelines have remained unchanged for almost 50 years, but children are now up to 20 per cent heavier.
Experts want the guidelines to be revised amid concern that some children are getting too little medication to treat their ailments. In these cases, they may need repeat prescriptions and they may suffer severe complications.
There are also fears that the problem may be driving antibiotic resistance as bugs get used to low levels of drugs used in children.
Guidelines on the amount of penicillin needed by children are mostly based on age bands, taking into account average weight, that were set in 1963. However, children's weight has increased — with a fifth of 11-year-olds now obese.
General weight increase
A ten-year-old today weighs 37kg (5st 11lb) on average, which is 7kg (15.5lb) more than in 1963 — a 20 per cent increase. In a study in the British Medical Journal, a team at King's College London and St George's, University of London, found that doses could be strikingly low and not in line with manufacturer's recommendations.
Paul Long, a senior medicines lecturer at King's College, said: "We were surprised at the lack of evidence to support the current oral penicillin 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."
He added: "Otitis media, or glue ear, is one of the most common problems needing antibiotic treatment and it is very likely to need a repeat prescription, possibly because children are not getting enough first time round."
The researchers called on the British National Formulary and the Department of Health to review the guidelines.
Simon Keady, a spokesman for the Royal Pharmaceutical Society, said: "The use of penicillins over many years for a wide variety of conditions should not stop us from continuing to identify the most appropriate dose which gives us the most effective outcomes. The work clearly shows the focus should not always be about new drugs but also looking at where we have historically centred dosing around age bands."
Each year, around five million children are prescribed oral penicillins.
Dr Long said penicillins were safe and effective when used in the right dose, but doctors wanted to be certain children with severe infections were being properly treated.
Professor Mike Sharland of St George's said: "We are saying that we need to develop a clearer system to check the doses used for older medicines."
