Tamiflu for Kids: Confusing Dosage Can Harm
Tamiflu Oral Suspension Marked in Milligrams, Often Prescribed in Teaspoons
Sept. 25, 2009 -- Confusing Tamiflu Oral Suspension prescriptions can lead
to dangerous over- or under-dosing of the flu drug, Roche and the FDA warn.
It's confusing even to medical professionals, find Kara Jacobson, MPH, and
her husband, a doctor.
Jacobson's 6-year-old daughter came down with swine flu and got a
prescription for Tamiflu Oral Suspension. The liquid drug is measured with a
syringe marked at 30, 45, and 60 milligrams. But the girl's prescription called
for her to receive three-fourths of a teaspoon twice a day.
Despite their medical training, it took Jacobson and her husband 30 minutes,
a Google search, and some diligent math to figure out that their daughter was
supposed to get a 45-milligram dose twice a day.
Milligrams measure weight; teaspoons measure volume. To translate
three-fourths of a teaspoon into milligrams, one has to figure out that a
teaspoon is 5 milliliters and that there are 12 milligrams in a milliliter of
Tamiflu. After that, a parent would have to solve this equation: 5 mL x 0.75 x
12 mg/mL Tamiflu suspension = 45 mg on the syringe.
"Most families and caregivers would not be able to identify or perform the
cumbersome calculation," Jacobson and colleagues wrote in a letter published in
the Online First edition of the New England Journal of Medicine.
Roche, the company that makes Tamiflu, has sent a warning letter to doctors
and pharmacists instructing them to prescribe the oral version of the drug in
milligrams. They warn that if prescriptions come in teaspoons or in
milliliters, an appropriately marked measuring device should be provided in
place of the syringe marked in milligrams.
"It's incredibly confusing to parents," Northwestern University researcher
Michael Wolf, PhD, MPH, who co-authored the NEJM letter with Jacobson, says in
a news release.
It's not just a quibble. Harm can come from getting the dose wrong.
"If you give too little, you risk making the treatment less effective," Wolf
says. "If you overdose, there may be a risk of toxicity to the patient."