BABYHALER - A NEW PEDIATRIC AERSOL DEVICE

Nebulizers have, until recently, been the mainstay of drug delivery by inhalation in babies and young children. The willingness of a young child to cooperate, however, is limited and the 10-12 mins needed to deliver drug using a nebulizer often limits the compliance with this mode of administration in infants. Therefore, drug delivery systems using the metered-dose inhaler (MDI) as the aerosol generator attached to valved holding chambers were developed. The breathing pattern of a baby with lung disease is quite different from that of older children and adults, for whom most large-volume devices were developed. Infants have a high respiratory frequency, small tidal volume, and low inspiratory airflow rate. Therefore, specific conditions for optimal drug use in this particular group of patients have to be met. Efficacy of topical drug delivery depends on the generation of aerosol particles with an adequate size distribution (technical prerequisites), the breathing pattern of the child (physiological requirements), and the willingness of a young child to cooperate with parental drug administration (practicality and compliance). Infants with lung disease have a tidal volume of 8-10ml/kg body weight. The volume of a spacer device must be such that about 5-10 breaths would be needed to provide an adequate dose. In addition, the dimensions of a spacer device must be such that sufficient drug particles of optimal size will be generated to minimize impaction and deposition within the device. The Babyhaler consists of a tubular chamber 230mm long, with a volume of 350ml and low-resistance inspiratory and expiratory valves. The drug aerosol, which has a mass median diameter of 3.21 mu m, is contained briefly within the holding chamber to allow the young child to inhale the medication during normal tidal breathing. Face masks used in conjunction with the Babyhaler provide an effective seal. The overall dead space volume was found to be approximately 55ml. Efficacy was demonstrated in several clinical trials that evaluated bronchodilator response to beta(2)-agonists, functional antagonism against bronchial aerosol challenge and efficacy of topical corticosteroids. These results plus additional handling studies have demonstrated that infants and young children can be treated using the inhalation route, and several important practical problems which previously limited drug compliance have been overcome.