Concentration and dosing of Tamiflu changed

The concentration of oseltamivir phosphate (Tamiflu) oral suspension has been reduced, and labels and dosing have changed accordingly, the FDA announced last week.

The concentration has been reduced from 12 mg/mL to 6 mg/mL, because the lower concentration is less likely to become frothy when shaken, which helps to ensure an accurate measurement, according to the FDA. The oral dosing device provided with the medication has also been changed to use milliliters instead of milligrams, and the dosing table on the medication package has been revised to include milliliter dosing based on the 6 mg/mL concentration.

Prescribers should use the new concentration and milliliter dosing for all future prescriptions of the medication, the FDA recommended. The manufacturer has instituted a voluntary take-back program to remove the 12 mg/mL medication from the marketplace, but some of the old product may remain in circulation this flu season. Patients should be warned about the possibility that they could receive either concentration to reduce the risk of medication errors, the FDA said.