Monday, September 12, 2011

New Acetaminophen (Tylenol) Formulation for Infants

You may have heard the buzz about acetaminophen infant drops earlier this year. The pain/fever reducer infant drops have since been removed from the market due to the risk of improper dosing. However, the children's formulation has remained and become the new standard.

According to a publication released by the FDA on July 21, 2011, there (were) 7 different strengths of acetaminophen one the market, in 3 different dosage forms: liquid, chewable, and tablet. The scenario painted by the FDA was this: "You’re in the drug store, looking for a fever-reducing medicine for your children. They range in age from 6 months to 7 years, and you want to buy one product you can use for all of them. So you buy liquid acetaminophen in concentrated drops for infants, figuring you can use the dropper for the baby and a teaspoon for the oldest. This could be a dangerous mistake."

Why would this be a mistake? Allow me to explain...

On average, a 6 months old may weigh 16.5 pounds.
On average, a 7 year old may weigh 50.5 pounds.
(Source: Buzzle.com)

As a pharmacist, I calculate out the dose using the formula:
  • Dose (mg) = 10-15mg/kg x weight (kg).
A person's weight is converted to kilograms (kg) by taking their weight in pounds (lbs) and dividing by 2.2.

So, in the examples given above:
  • The 6 month old would weight 16.5lbs/2.2 = 7.5kg
  • The 7 year old would weigh 50.5lbs/2.2 = 22.9kg.
The appropriate dose for the 6 month old would be 10-15mg/kg x 7.5kg = 75-112.5mg.
The appropriate dose for the 7 year old would be 10-15mg/kg x 22.9kg = 229-343.5mg.

The infant drops came in 80mg/0.8mL with a bulb syringe (medicine dropper) to administer the medication. What some folks were doing, was using these concentrated drops for both kids but using the dropper for the baby and a teaspoon for the 7 year old, for example. A teaspoon (5mL) of the infant drops would equal 500mg of acetaminophen. Recall in the example above, the maximum dose for a 7 year old weighing 50.5lbs (22.9kg) would be 343.5mg. So, a teaspoon of the infant drops would be overdosing the 7 year old by over 150mg.

Remember, the infant drops were concentrated; specially designed for infants because infants have a more difficult time swallowing a large volume. Had the appropriate product been selected for the 7 year old (a children's acetaminophen liquid product is 160mg/5mL), the child could have received 2 teaspoonsful (10mL) and been within his/her dosing range because this would have equaled 320mg.

This type of scenario is what prompted the FDA Advisory Panal to recommend:
  • That liquid, chewable, and tablet forms be made in just one strength.
  • That dosing instructions to reduce fever be developed for children as young as 6 months. (The old instructions on the children's product started at the age of 2 years old and for under 2, to "consult a doctor")
  • That dosing instructions be based on weight, not just age.
  • Setting standards for dosing devices, such as spoons and cups, for children’s medicines. (The old standards were, simply, unstandardsized, with some using milliliters (mL) while others used teaspoons (tsp))
Now, the new infant product will be:
  • The same concentration as the children's product (160mg/5mL)
  • Complete with dosing instructions for age 3 months and up, advising not to give acetaminophen to a baby under 3 months without a doctor's approval
  • Advising that the proper dose for your child is based on weight, not age
  • Clarifying to always use the measuring device that comes with the medicine — not a spoon from the kitchen
Some parents may be uncomfortable with calculating out the appropriate dose for their child based on the formula I gave earlier and that is why the manufactures have calculated the appropriate dose, based on a weight range in pounds, for you! This chart is provided by BabyCenter.com and is a must have to keep in your medicine cabinet if you plan on keeping acetaminophen on hand for your child's pain/fever. It is a super handy guide for showing the babysitter how much acetaminophen to give your child, should he/she develop a fever or bump his/her head while you are away. The chart compares the old product with the new product, too. Please use this free resource and spread the word to other parents and caregivers about the new acetaminophen product. Also, watch those store shelves because there will be a time that both the old and the new product will be on the shelf and you need to know which one you picked up!

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