Abstract
ABSTRACT
Inhalation delivery of medicinal agents offers significant therapeutic advantages, including direct administration to target tissues, rapid uptake and distribution, and avoidance of drug degradation and side effects associated with other routes of administration. Medical air-jet nebulizers are widely used in these applications, but recent advances in drug carrier systems development suggest that air-jet nebulization may not be the most appropriate technique for aerosolization of emerging energy-sensitive carriers such as liposome suspensions. In this work, net energy input to therapeutic aerosols and the resulting damage to drug carrier systems are examined from both theoretical and experimental approaches. From theory, equations describing net energy input are derived for air-jet nebulizer and spinning disk aerosol generator systems, and evaluated using design and operating values for two commercially available instruments, a Collison 3-jet nebulizer and an MkII Spinning Top Aerosol Generator (STAG). Net energy input is seen to be approximately three to four orders of magnitude greater for nebulized aerosol than for STAG-generated aerosol, suggesting a much greater potential for damage to energy-sensitive drug carriers. These data are found to be in agreement with measurements of drug "leakage" from aerosolized liposomes encapsulating sodium cromoglycate, a widely used water-soluble drug, in that STAG aerosols exhibit a 4- to 6-fold greater fraction of encapsulated drug in the delivered (sampled) aerosol than nebulized aerosol. The pharmacokinetic implications of these findings are significant; however, additional work is needed to further evaluate the capabilities of various types of spinning disk aerosol generators in therapeutic applications.
Get full access to this article
View all access options for this article.