Inhalation therapy in obstructive airways disease : evaluation and instruction on metered dose inhaler technique

Abstract

The value of inhaled drugs has been recognised for millenia by ancient civilizations (Miller, 1973). Inhalation therapy has many advantages including drug delivery direct to site of action, rapid onset of therapeutic effect (Plit et aI, 1972) minimisation of dose required (Newman & Clarke, 1985) minimisation of systemic side-effects (Sterling, 1978), avoidance of first pass metabolism (C & D Livingstone, 1988) and noninvasive delivery technique. However, specific drug delivery may be hindered by defence mechanisms of the respiratory tract (Reiser & Warner, 1986), and other problems may also be present since drug delivery depends on the mechanism of deposition (Newman, 1984), particle size (Rees et aI, 1982), inhalation mode (Pavia et aI, 1977) and patient factors. The types of drugs used in inhalation therapy include the beta adrenergic stimulants, anticholinergic bronchodilators, methylxanthines, sodium cromoglycate, corticosteroids, water and saline aerosols, mucolytics and antibiotics. The delivery systems employed are the nebuliser, dry powder inhalers and the metered dose inhalers (MDls). Recently, a new device has been developed, and this is the Turbohaler.