UK experts: paediatric penicillin dosing guidelines need updating

Taken from the British Medical Journal (BMJ) – by Bruce Sylvester – A Study published on Dec. 20, 2011 in the British Medical Journal suggests that some children may not be receiving effective doses of penicillin, which could lead to failed treatment and to antibiotic resistance. Oral penicillins (such as amoxicillin) account for nearly 4.5 million of the total six million annual paediatric prescriptions for antibiotics in the UK.The investigators undertook a relevant literature review. They found that prescribing based on age bands was suggested in the early 1950s, based on the results of oral dosing studies. A recommendation to use age banding for all antibiotics in children was published in the BMJ in 1963, and these same recommendations still remain in use.

The researchers found that the age band guidelines set in 1963 were accompanied by average weights. Doses were based on fractions of the widely used adult doses. The dosing bands are: birth to one year (10kg); two years (13kg); five years (18kg); and 10 years (30kg). However, according to the Health Survey for England 2009, the average weight today of a five year old is 21kg and a 10 year old is 37kg, indicating that average weights today are up to twenty percent higher than in 1963.

The investigators noted that under-dosing could lead to sub-therapeutic concentrations. They also noted that adult penicillin recommendations have been re-evaluated taking modern weights into consideration, and penicillin doses have consequently increased.

Professor Mike Sharland from St George’s, University of London, and co-author of the study said, “Although there is now a very formal process of determining the right dose for new drugs being licensed for use in children, we also need to check more carefully that the guidelines are still correct for older drugs that have been used for a long time. We are not saying the current doses are wrong or unsafe and parents should always give the medicine at the doses prescribed by their GP. We are saying that we need to develop a clearer system to check the doses used for older medicines.”

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