Apr. 2, 1998 By Morgan Marshall
GAINESVILLE, Fla.---Asthma experts at the University of Florida and Wellington College of Medicine in New Zealand are calling for the pharmaceutical industry and regulatory agencies worldwide to ban the use of preservatives in medications intended for patients with asthma and chronic pulmonary disease.
An article in the current issue of the journal Pharmacotherapy cited studies linking widely used preservatives with a worsening of airway obstruction in asthma patients. Prompted by the article and supporting information provided by a UF pharmacist, the Florida State Board of Pharmacy issued a written statement alerting the pharmacy community to the risks associated with the preservatives. The warning does not include the commonly used press and breathe metered dose inhalers, which do not include the preservatives.
The writers identified the stabilizer edetate disodium (EDTA) and the preservative benzalkonium chloride (BAC) as the most frequently used agents in nebulizer solutions used to treat asthma, emphysema and chronic bronchitis. Nebulized solutions are medications delivered by an air compressor in the form of a fine spray designed to be inhaled by patients.
While nebulized solutions contain medications that open the bronchial tubes leading to the lungs, researchers have found that the amount of BAC contained in a standard prescription vial actually constricts these airways, counteracting the effects of the medication and sometimes worsening lung function in the patient. Similar effects were reported for EDTA when higher doses of the stabilizer were inhaled.
The Pharmacotherapy article, written by pulmonologists in Wellington, New Zealand, with contributions from University of Florida clinical pharmacist Leslie Hendeles, offered a review of studies using medications with and without the added preservatives.
The findings suggest that BAC fails to provide any real benefit in terms of reducing bacterial contamination related to the use of nebulized medications, and poses a substantial risk to the patient by constricting airways and reducing the effectiveness of the medication.
Hendeles, a professor in UF's College of Pharmacy and the pediatric pulmonary division within the College of Medicine, says that safer, preservative-free medications are available in sterile, single-dose vials. Hendeles warns, however, that a variety of nebulizer productsmanufactured and sold in the United States are mistakenly considered by pharmacists to be therapeutically equivalent, regardless of whether they contain preservatives. Consequently, even if a physician has prescribed a product that is preservative free, the pharmacist may legally substitute another form of the medication that contains preservatives.
The potential risks associated with the preservatives prompted the Florida State Board of Pharmacy to call attention to the problem in a newsletter issued to pharmacists throughout the state. Hendeles says that other state boards of pharmacy may follow suit once the information becomes widely distributed.
Hendeles and his colleagues are urging regulatory agencies such as the U.S. Food and Drug Administration and the pharmaceutical industry to ban the use of preservatives like BAC in bronchodilator nebulizer solutions, and to make sure that all nebulizer solutions for asthma patients are available in sterile, preservative-free, single-dose vials.
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