Actual pentamidine dose delivered by Respigard II nebulizer

Abstract

and a substantial amount of solution was left unused in the nebulizer. This differs from the FDA guideline that recommends a complete nebulization until the chamber is empty. In recent studies [6], delivery of pentamidine from the RPG II was measured as a function of time until dryness. Operation of the nebulizer, however, was interrupted every 5 min to collect samples, which could alter the delivery characteristics of the nebulizer.The purpose of the present study was to determine the delivered dose of pentamidine aerosol with continuous operation of the nebulizer until dryness. Delivered dose was measured with and without an oropharyngeal model to investigate the influence of the upper airways. The results of the present study may supplement the previous results and may be used as the basis of comparing different delivery systems and of interpreting the therapeutic effect of pentamidine aerosol. Materials and methods Respigard II nebulizer system (RPG II)The system consists of an air jet nebulizer, a Y-piece with two one-way valves installed at the inspiratory and expiratory limbs, an expiratory filter, and a mouthpiece ( fig. 1). The nebulizer is connected to the side of the inspiratory limb of the Y-piece via a T-connector. A short corrugated hose and a one-way valve are attached to the inlet port of the T-connector. During operation, aerosols are generated continuously with compressed air at 7.25 kPa, at which a jet airflow rate of 6 L·min -1 is ABSTRACT: The Respigard II nebulizer system is the approved method to deliver pentamidine aerosols in the USA. Although continuous operation of the nebulizer until dryness is a designated regimen, the actual pentamidine dose delivered under the operating condition has not been thoroughly studied. Pentamidine solutions (300 mg in 6 mL water) were nebulized continuously with the Respigard II nebulizer system until dryness (40 min operation). Aerosols were delivered to the lower airways via an oropharyngeal model and sampled on a filter with a standard breathing mode of 20 breaths·min -1 frequency and 750 mL tidal volume. Intermediate samples were also obtained for the initial 20 min delivery.The pentamidine dose delivered to the mouth was 1.6% of the dose placed in the nebulizer. Of the dose delivered to the mouth, 92% was delivered during the initial 20 min period. Aerosol loss in the oropharyngeal model was 15% of the dose delivered to the mouth or 0.24% of the dose initially placed in the nebulizer.Pentamidine dose delivered to the lower airways was a very small fraction of the initial dose in the nebulizer. A partial delivery for the initial 20 min was nearly comparable to complete delivery.

Controlled inhalation improves central and peripheral deposition in cystic fibrosis patients with moderate lung disease

“…Two potential strategies may improve the penetration of antibiotic‐containing droplets into the peripheral regions of the conducting airways. One option would be to reduce the particle size of inhaled droplets, 5,6 but with current technology, this would inevitably result in a reduced rate of drug output and significantly increased treatment times 7 . At present, there are no commercial devices that permit tailoring of droplet size to disease severity.…”