Concentration of Popular Flu Drug Lowered

The FDA has announced important product safety changes to the influenza drug Tamiflu (oseltamivir phosphate) for oral suspension on July 11. The agency worked with the manufacturer, Genentech (part of the Roche Group), to make these changes, which aim to reduce the possibility of prescribing and dosing confusion that can lead to medication errors.

The changes to Tamiflu oral suspension and the product label include:

• A change to the concentration of Tamiflu from 12 mg/mL to 6 mg/mL. The lower concentration of Tamiflu is less likely to become frothy when shaken, which helps to ensure an accurate measurement. The 12 mg/mL concentration will no longer be marketed after current supplies run out.
• A change in the measurements of the oral dosing device from milligrams to milliliters.
• A change in the dosing table table for Tamiflu to include a column for the volume based on the new 6 mg/mL concentration.
• Revised container labels and carton packaging.
• Revised compounding instructions for 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.

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 to remove the 12 mg/mL product from the marketplace.

There are no quality issues with the 12 mg/mL product—it is still useable through its expiration date. However, FDA encourages participation in the Take Back Program to limit the potential for product confusion.

The 12 mg/mL product will remain in the marketplace and in state or national stockpiles until current supplies expire. Therefore, it is important for healthcare professionals 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 (2011-2012). Steps should be taken to avoid the potential for a medication error due to confusion between the two concentrations.

For complete background information on Tamiflu, please click here.

Additional Information for Patients

• The concentration of Tamiflu for oral suspension is changing and you may get either concentration at your pharmacy during the next flu season.
• The new Tamiflu for oral suspension container label and carton packaging look different from what you may have taken in the past.
• The new oral dosing device is different and the volume (mL) of your dose may differ from past prescriptions.
• Check with a healthcare professional if you have any questions about the dosing directions, how to measure a dose using the new dosing device, or about which concentration of Tamiflu for oral suspension you have.
• Report any side effects you experience or medication errors to your healthcare professional and the FDA MedWatch program using the information in the “Contact Us” box at the bottom of the page.

Additional Information for Pharmacies

• The most important measure a pharmacy can take is to participate in the Take Back Program and replace the 12 mg/mL concentration of Tamiflu for oral suspension with the new 6 mg/mL concentration.
• Pharmacies should contact their distributor if they have unused/undispensed 12 mg/mL Tamiflu for oral suspension to determine if the product may be returned through the Take Back Program before August 31, 2011.
• Pharmacists should verify that each prescription for Tamiflu for oral suspension contains a concentration (mg/mL) and a dose (mL). If the concentration and dose are not specified, then the pharmacist should clarify the prescription with the prescriber.
• Pharmacists should ensure that the units of measure for the dosing instructions on the bottle match the oral dosing device that is provided (e.g., for the new 6 mg/mL product, the units of measure for both the drug and the device should be in milliliters).
• Pharmacists should ensure that the correct dose, dosing instructions, and oral dosing device are provided for the patient and are consistent with the concentration of Tamiflu for oral suspension (6 mg/mL or 12 mg/mL) that the patient will receive.

Click here to view the revised dosing chart for Tamiflu.