Use of Aerosolized Antibiotics in Patients With Cystic Fibrosis: Overview of Nebulizer Options
These data demonstrate that even with the more efficient nebulizer (Pari LC Plus), mean serum concentrations of tobramycin following a twice-daily 300-mg aerosol dose still averaged 1 ^g/mL. Even though serum concentrations obtained by inhalation were approximately one tenth those observed following parenteral administration, the mean peak concentrations of tobramycin in the sputum were at least 15-fold greater following aerosol administration than those achieved after parenteral administration. Although sputum concentrations are not homogenous and their measurement does not represent the true deposited dose, the ability to achieve high local concentrations in the sputum, while keeping low serum levels, suggests a potential clinical advantage of aerosol administration of tobramycin over parenteral administration. However, there remains concern about the distribution of aerosolized antibiotics due to extensive airway obstruction from sputum.
Overview of Nebulizer Options
Basics of Aerosol Delivery: Ideal Particle Size and Particle Clearance Aerosols are droplets suspended in air. For most aerosols, deposition in the lower airway and alveolar space in humans occurs with particles between 1 and 5 ^m, the larger of which tend to be deposited more proximally. Particles < 1 ^m have insufficient mass for effective drug delivery and many submicronic particles are exhaled. Particles > 5 ^m are usually deposited in the oropharynx and are subsequently cleared by swallowing. read only
Following inhalation and lung deposition of an aerosol, clearance results from three mechanisms: absorption, mucociliary clearance, or expectoration of sputum. The latter two mechanisms usually only occur with drug deposited in the airways.
Classes of Inhalation Devices: There are five current classes of inhalation devices that can deliver drug to the respiratory tract: dry powder inhalers, metered dose inhalers, micronebulizers, ultrasonic nebulizers, and jet nebulizers. In their current form, dry powder inhalers and metered-dose inhalers are impractical to deliver the mass of aminoglycoside antibiotics required for efficacy. Micronebulizers are devices that produce aerosols by forcing a solution through a sieve at high pressure and have not been clinically tested for antibiotic delivery.