Dosing confusion for liquid Tamiflu?
New England Journal of Medicine. Prescriptions for the drug are often written with doses in fractions of a teaspoon, but the dropper packaged with the drug is marked in milligrams, requiring a difficult conversion of units, said Dr. Ruth Parker of the Emory University School of Medicine, lead author of the paper.
"It's an egregious error that there is a conflict in the prescription labeling instructions and the dosage device that comes in the exact same box," said co-author Dr. Michael Wolf of the Northwestern University Feinberg School of Medicine. "It's incredibly confusing to parents."
The conflict was discovered by co-author Kara Jacobson, a senior research associate at Emory's Rollins School of Public Health and mother of a 6-year-old girl who contracted pandemic H1N1 influenza, popularly known as swine flu. Their Tamiflu prescription called for three-quarters of a teaspoon of the drug twice a day. Jacobson and her husband, an internist, had to do a Google search and solve a complex equation to determine the correct dose:
5 ml (volume of a tsp) x .75 x 12 mg/ml of Tamiflu = 45 mg
It took them both working together for 30 minutes to solve the equation, and they suspect that many parents would have greater difficulty doing so. Their recommendation: If a prescription calls for teaspoons or fractions of a teaspoon, then the syringe should be marked in teaspoons.
-- Thomas H. Maugh II
Photo: A syringe, marked in milligrams, that came with a Tamiflu prescription and the label calling for a dose of three-quarters of a teaspoon. Credit: New England Journal of Medicine