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Children’s dosage recommendations for oral penicillin need to be updated to account for increases in children’s average weights, ac-cording to researcher Umar Ahmed and a team of UK specialists.
In a feature published online in the BMJ (15 December 2011), Mr Ahmed — a pharmacist and paediatric pharmacy researcher at the School of Pharmacy, University of London — and colleagues point out that the same penicillin dosage recommendations have been used for children for the past 50 years, whereas the adult dosage has gone up over the years.
Most paediatric penicillin doses are based on age bands, with an average weight assumed foreach age group. However, children have got heavier since these average weights were calculated (see Panel) and failing to take this change into account could result in suboptimal dosing, the authors say. This could increase antimicrobial resistance and make further treatment necessary, increasing the risk of severe complications.
In addition, published risk-benefit analyses on the therapeutic balance of antibiotic pre-scribing for upper respiratory tract infections assume doses are adequate. If current doses are, in fact, suboptimal, then the number needed to treat to prevent any severe complications is higher than estimated, the authors say.
Changes have already been made to paediatric antiretroviral dosing guidelines to take into ac-count changes in growth and obesity. The same changes should now be made for oral penicillins, the authors add.
“We also need to establish more clearly which children really need antibiotics in the era of pneumococcal conjugate (PCV 13), Haemophilus influenzae B, and meningitis C vaccines,” they say.
Steve Tomlin, consultant pharmacist at the Evelina Children’s Hospital, London, and spokesman for the Royal Pharmaceutical Society, said: “This [BMJ feature] rightly points out that average weights for the population are changing and thus the banding needs to be re-viewed over time.”
But he added that swapping to a dosage system based on weight could have its own complications in practice, including the need for calculations and the possibility of hard-to-measure doses. “Any changes must be made[with] scientific justification and risk management in mind,” he said.
Average weights rise
According to the BMJ feature, the British National Formulary for Children’s penicillin dosage recommendations, which have not been updated since they were first published in 1963, are based on average weights of: 10kg for a baby up to one year of age; 13kg for a child two years of age; 18kg for a five-year-old; and 30kg for a 10-year-old.
However, data from the 2009 Health Survey for England show average weights for five-and 10-year-old children are now 21kg and 37kg, respectively.
