Tamiflu to come in new concentration; use care when dosing

The influenza drug Tamiflu is changing its concentration in order to reduce prescribing and dosing errors.

The changes to Tamiflu (oseltamivir phosphate) oral suspension include reducing the concentration from 12 mg/mL to 6 mg/mL. The new, lower concentration is less likely to become frothy when shaken, which helps ensure an accurate measurement. The safety label also includes a change in the measurements of the oral dosing device from milligrams to milliliters.

Tamiflu will also include a column for the volume (mL) based on the new 6 mg/mL oral suspension from Tamilfu capsule in an emergency situation only if the commercially manufactured Tamiflu for oral suspension is unavailable.

Tamiflu is in a class of medications called neuraminidase inhibitors. These drugs work by stopping the spread of the flu virus in the body. Genetech the manufacturer of Tamiflu for oral suspension, plans to begin distribution of the new 6 mg/mL product this month. The company has instituted a voluntary Take Back Program for wholesale buyers, distributors and pharmacies to remove the 12 mg/mL product from the marketplace. The 12 mg/mL product will remain in the marketplace in state or national stockpiles until current supplies expire.

It is important for doctors to be aware that a patient may potentially receive either concentration (6 mg/mL or 12 mg/mL) from their pharmacy during the next influenza season. Steps should be taken to avoid the potential for a medication error due to confusion between the two concentrations. Dosing should be listed in milliliters on all prescriptions for Tamiflu for oral suspension.

Any side effects with this or any drug should be reported to the FDA MedWatch Adverse Event Reporting Program at