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November 3, 1993

Metered-Dose Inhalers: Drug Delivery Over the Life of a Canister

Author Affiliations

Hahnemann University Philadelphia, Pa

JAMA. 1993;270(17):2050. doi:10.1001/jama.1993.03510170040014

To the Editor.  —In a recent letter, Bergner et al1 called attention to a problem in the use of metered-dose inhalers (MDIs) in the treatment of asthma: some exacerbations occur when patients use MDIs beyond the number of sprays specified by the manufacturer.A related problem can occur when the dose per spray specified by the manufacturer actually delivered declines substantially before the specified number of inhalations is reached. Being retired, I can only provide evidence of this phenomenon from my own personal experience.I have been using flunisolide inhalations (AeroBid with the company's spacer, Forest Pharmaceuticals Inc, St Louis, Mo) for the treatment of cough-variant asthma since 1990, using the company's directions. My dose has always been two inhalations twice a day and this is very effective in the control of my symptoms. However, after the 17th day of use I found that the strength of the spray declined