News: A Healthy Dose for Inhalers


FDA's draft guidance for metered dose inhalers will help patients keep track of their dosages.

FDA is recommending that metered-dose inhalers (MDIs) for oral use come with a dose-counting device to enable patients to track how many doses of medication are left.

In a draft guidance published December 10, which can be viewed at http://www.fda.gov/cder/guidance/4806dft.pdf, the agency noted that currently marketed oral MDIs have no practical way to track the number of doses left. This, it stated, can cause patients to throw away MDIs with doses left, which is wasteful, or to use the product beyond the recommended number of doses, which can be dangerous.

MDIs usually contain more formulation than required to expel the labeled number of doses. The excess is there to ensure the dosing consistency of each spray up to the labeled number. Doses after the labeled number usually are inconsistent and eventually contain negligible amounts of drug substance, so it is important that the patient does not assume that these are proper doses.

Today, however, the agency states, "technological advances have made it possible for manufacturers to incorporate into their devices economical, reliable, integrated dose counters to reflect how many actuations remain in a canister." Therefore, the agency wants new oral MDIs to adopt dose counters. Oral MDIs currently marketed in the United States do not have dose counters, though some multidose dry-powder inhalers do.

The draft guidance calls for dose counters, through a direct numeric count or color coding, to provide a clear indication of when the MDI is approaching its recommended number of doses, and when it has reached or exceeded that number. The "approaching" signal should occur far enough in advance for patients to have time to obtain a new MDI. Numeric counts should count downward to zero. If a low frequency of error is unavoidable, the device manufacturer should ensure it avoids undercounting, which could create the dangerous situation of patients assuming they have medication left in the MDI when they do not. Lock-out mechanisms to prevent doses beyond the labeled number are an option, but they should not be used with treatments for acute bronchospasm, for which even a partial dose could be life-saving.

The guidance would not apply to currently marketed MDIs, or nonoral MDIs. Written comments were due by February 11. For further information, contact Sandra L. Barnes at 301/827-1050.

Erik Swain


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