Label for Tamiflu for oral suspension revised, reflects new concentration

The concentration of the influenza drug oseltamivir phosphate (Tamiflu, Genentech) for oral suspension has been reduced from 12 mg/mL to 6 mg/mL to reduce the possibility of prescribing and dosing confusion that can lead to medication errors, FDA announced.

The lower concentration is less likely to become frothy when shaken, which helps to ensure an accurate measurement.

Genentech and FDA are revising the product label and packaging to reflect the change. Other changes to the product label include:

• A change in the measurements of the oral dosing device from milligrams (mg=weight) to milliliters (mL=volume)
• A change in the dosing table to include a column for the volume (mL) based on the new 6 mg/mL concentration
• Revised compounding instructions permitting pharmacies to prepare a 6 mg/mL oral suspension from Tamiflu capsules in an emergency situation only if the commercially manufactured Tamiflu for oral suspension is unavailable

Tamiflu is indicated for the treatment of uncomplicated influenza caused by virus types A and B in patients 1 year of age and older who have been symptomatic for no more than 2 days, and for the prophylaxis of influenza. Tamiflu is in a class of medications called neuraminidase inhibitors, which work by stopping the spread of the influenza (flu) virus in the body.

Genentech 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 in an effort to remove the 12 mg/mL product from the marketplace. The 12 mg/mL product will remain in the marketplace and in state or national stockpiles until current supplies expire.

It is important for healthcare professionals to be aware that patients may receive either concentration (6 mg/mL or 12 mg/mL) from their pharmacies during the next influenza season (2011 to 2012). Steps should be taken to avoid the potential for a medication error resulting from confusion between the 2 concentrations. Prescribers should include the new concentration (6 mg/mL) and dose in milliliters on all prescriptions for Tamiflu for oral suspension.