SACRAMENTO, Calif. -- Rescue inhalers for asthmatics don't keep track of bronchodilator doses used or remaining, leaving some patients in the lurch when they need the drugs most.
SACRAMENTO, July 28 -- Asthmatics who reach for rescue inhalers during an exacerbation may get a nasty surprise when they find that the tank has run dry without warning.
In a random survey of 500 U.S. families with asthma, the investigators found that one-fourth of those who said they used bronchodilators when they had symptoms of wheezing, coughing or shortness of breath reported that on one or more occasion they found their inhalers empty during an asthma exacerbation.
Seven of these 87 patients had to call 911 for help, Bradley E. Chipps, M.D., of the Capital Allergy & Respiratory Disease Center here, and colleagues, reported in the July issue of the Annals of Allergy, Asthma & Immunology.
The investigators also found that many patients were using bronchodilators more often than recommended and refilling prescriptions much more frequently than necessary, suggesting that either their asthma was poorly managed, or they were throwing away partially full canisters out of concern that they might run out of medication when they needed it.
"Given the necessity of a reliable dose counting method, it is clear that manufacturers should include dose counters as a standard feature of every metered-dose inhaler," the investigators wrote.
The pressurized metered dose inhaler is the only medication delivery system approved by the FDA that does not allow patients to reliably tell whether they have medication left as they continue to use it, the investigators said.
Asthmatics use pressurized metered-dose inhalers both for rescue medications such as albuterol, and for maintenance therapies such as inhaled corticosteroids, which could have serious or even fatal consequences, wrote John Oppenheimer, M.D., of the University of Medicine and Dentistry of New Jersey, in Newark, in an accompanying editorial.
The study results suggest that "in the real world asthmatic patients demonstrate a frightening lack of knowledge regarding proper use of inhalers and are consistently underusing their inhaled corticosteroid and overusing their rescue beta-agonist inhalers," Dr. Oppenheimer commented. "Both these patient practice patterns have been associated with an increase in morbidity and mortality."
To determine how patients judge how much medication is remaining in their inhalers and whether they are discarding them when partially full or using them beyond the indicated number of doses, the authors conducted a telephone survey of a random sample of 500 asthma families across the United States.
The sample was drawn from member families of the Allergy & Asthma Network Mothers of Asthmatics in Fairfax, Va., Nancy Sander, a co-author. She is founder and president of the organization.
The survey consisted of a 6.5 minute telephone interview in which participants were first asked what the asthmatic family member used for coughing, wheezing, or shortness of breath, and only those who named bronchodilators were asked additional questions. These participants were asked how often they used the drug, how often they refilled the prescription, and how they measured the number of doses used and remaining.
The authors found that 31.6% of the 500 respondents participating in the telephone interview named an inhaled corticosteroid or bronchodilator and inhaled corticosteroid combination as the inhaler they used when wheezing, coughing, or short of breath.
Of the 342 respondents who said they or the asthmatic family member used a bronchodilator, 31.9% used the inhalers daily, 18.7% said weekly, 23.4% said monthly, and 23.1% said less than once per month.
In all 53.8% of the bronchodilator users refilled their prescriptions more frequently than recommended by national guidelines. Some reported refilling monthly, but if they had used their inhalers as intended, would only need to refill once or twice a year at most, the investigators wrote.
"Another alarming finding was that only 36% of bronchodilator users reported ever having been told to keep track of pressurized metered-dose inhaler doses used," Dr. Chipps said "But without an integrated dose counter, there is no reliable way for patients to track medication usage."
Of the minority of bronchodilator users who had been advised to keep track of their doses, 79% had been advised to do so by a physician, 6% by a pharmacist, and 3% by a nurse.
In all, 87 (25%) of the bronchodilator users said they found the inhaler empty during an exacerbation, and seven had to call 911 for rescue.
"Also, most (nearly 82%) of the subjects considered their pressurized metered-dose inhaler empty only after noting that nothing further came out of their inhaler. Relying on this technique for determining when an inhaler is empty is flawed, because manufacturers provide 20% to 80% extra doses of propellant after all the medication has been consumed," the authors wrote.
They noted that all of the available methods of measuring doses used -- keeping a diary, as recommended by the FDA; judging by the strength of the puff; shaking the canister; and floating the canister in water are all flawed and inaccurate, the authors cautioned.
They noted that in patient preference surveys, the presence of a counter on the Advair Diskus device, which delivers measured puffs of Flovent (fluticasone) and Serevent (salmeterol), was a deciding factor in their choice of the device over an alternative.
They called on manufacturers of pressurized metered-dose inhalers to include counters in every device sold, an idea with which Dr. Oppenheimer, supported in his editorial.
"The authors' conclusion that manufacturers of inhaled medicines include dose counters as a standard feature on every multi-dose inhaler device appears reasonable," he wrote. "Otherwise, our patients are left to question whether their inhaler device is 'running on empty'."