Children Might Need Higher Doses of TB Drug Than Adults, Study Says

Children metabolize the tuberculosis medication isoniazid faster than adults and might require higher doses of the drug to adequately treat the disease, according to a study published in the June 2005 issue of the Archives of Disease in Childhood, Reuters reports. Simon Schaaf of Stellenbosch University in South Africa and colleagues studied the absorption and elimination of isoniazid in 64 children younger than 13 with TB. They found that the average rate of elimination was significantly different depending on the children's genetic make-up. However, among children with similar genetic profiles, the elimination rate decreased with age. When the researchers compared the children's isoniazid blood concentration levels with genetically similar adults, they found that the adults' concentration levels were significantly higher. "Children develop less side effects from isoniazid compared with adults," Schaaf said, adding, "A dose of 10 milligrams per kilogram, as we now recommend, should be safe in by far the majority of cases and is currently already the recommended dose in children in developed countries. In an accompanying ADC editorial, Noel Cranswick of the University of Melbourne and Kim Mulholland of the London School of Hygiene & Tropical Medicine say that the study "highlights the fact that not only are higher doses required in childhood ... but also that children are as metabolically (variable) as adults" (Douglas, Reuters, 6/16).