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Inhaled respiratory medications and the use of chlorofluorocarbons (CFCs)
Author(s) -
Pierce Robert J,
Seale J. Paul,
Ruffin Richard E
Publication year - 1991
Publication title -
medical journal of australia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.904
H-Index - 131
eISSN - 1326-5377
pISSN - 0025-729X
DOI - 10.5694/j.1326-5377.1991.tb121268.x
Subject(s) - medicine , inhalation , intensive care medicine , toxicology , anesthesia , biology
Objective To assess the use of chloro‐fluorocarbons (CFCs) in metered‐dose aerosols against the background of community concerns regarding the adverse environmental effects of CFCs. Data sources Data on the constituents of currently available metered‐dose aerosols were supplied by the manufacturers, and details of chemistry and safety were obtained from monographs and papers published in the medical literature. Study selection Five papers, published in the early 1970s when metered‐dose aerosols first became popular, were reviewed for safety data on CFCs. Several chapters in monographs were searched for data on the nature and function of CFCs in metered‐dose aerosols, and five papers were the source of information on alternatives to CFCs as vehicles for the delivery of inhaled respiratory drugs. Data synthesis The medical use of CFCs accounts for only 1.5% of this total production in Australia, the majority being used for refrigeration, air‐conditioning and other commercial or industrial purposes. The physicochemical properties of CFCs are such that they function as a suitable storage medium for active drugs within the canister and as an ideal vehicle for drug delivery. Approximately 20 s after inhalation of a clinically recommended dose of a bronchodilator metered‐dose aerosol, CFCs are detectable in the blood, but the concentrations decline rapidly (half‐life<40 s). Although CFCs have been shown to sensitise the myocardium to the arrhythmogenic effects of catecholamines in experimental animals, the requisite concentrations can only be achieved by patients if they inhale from a canister on every breath for approximately 20 successive breaths. Conclusions CFCs used in metered‐dose aerosols are an effective storage medium and a convenient vehicle for drug delivery. They are non‐toxic ‐ unless amounts far in excess of the clinically recommended doses are used, when arrhythmogenic effects may occur. The medical use of CFCs has minimal environmental impact compared with their industrial and commercial use. Dry powder delivery systems offer an alternative approach, and future research will yield nonozone‐depleting CFCs suitable for replacing those in current metered‐dose aerosols.