title: Delivery of glucocorticoids by jet nebulization: aerosol characteristics and output.
abstract: BACKGROUND
  Since inflammation has been identified as a critical factor in the pathogenesis of asthma, use of inhaled glucocorticoids has increased. Because young children are often unable to coordinate properly the use of metered-dose inhalers and no glucocorticoids preparations for nebulization have been approved in the United States, parenteral and intranasal glucocorticoids preparations are occasionally administered by nebulization.
  
  
  METHODS
  We examined whether a parenteral preparation (triamcinolone acetonide [TAA]; Kenalog) could be delivered by nebulization. TAA, 1000 micrograms (0.1 ml), was placed in the nebulizer bowl (MB5 [MeFar, Brescia, Italy] or Pari-Jet [Dura Pharmaceuticals, San Diego, Calif.]), then diluted with 2.9 ml normal saline solution for a total volume fill of 3 ml. Using a laser particle analyzer, high-performance liquid chromatography, and cascade impactor, we examined the percentage of aerosol volume produced with particles in the respirable range of 1 to 5 microns in diameter, actual TAA output (in micrograms) and concentration of TAA contained in the particles within the respirable range.
  
  
  RESULTS
  Laser particle analysis indicated that 34% +/- 3% (mean +/- SEM) (MB5) and 47 +/- 3% (Pari-Jet) of the total aerosol volume produced were within the respirable range of 1 to 5 microns in diameter, and this remained consistent throughout nebulization. The nebulizer was stopped serially for determination of TAA output with high-performance liquid chromatography. TAA output (1000 micrograms less the amount in micrograms remaining after nebulization) was essentially complete after 2 minutes with the Pari-Jet and within 4 minutes with the MB5 and totaled 352 +/- 19 micrograms and 367 +/- 9 micrograms, respectively. Finally, cascade impactor studies confirmed that 33.4% of the TAA aerosol generated by the MB5 nebulizer was contained in particles in the respirable range.
  
  
  CONCLUSIONS
  Approximately 35% (Pari-Jet) and 37% (MB5) of the initial 1000 micrograms of TAA was delivered with the two nebulizers tested. The particles generated within the respirable range were limited to 34% (MB5) and 47% (Pari-Jet) of the amount delivered. TAA was equally distributed in the particles generated. The theoretic amount delivered in the respirable range was approximately 12.5% for the MB5 nebulizer on the basis of the cascade impactor and 16.5% for the Pari-Jet (assuming TAA distribution equivalence) of the TAA placed in each of the nebulizers. Additional clinical studies are needed to define efficacy and safety in view of the excipients used in preparing the parenteral preparation.
authors.affiliation: Department of Pediatrics, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206, USA.
authors.forename: J
authors.initials: J
authors.lastname: Leflein
authors.forename: E
authors.initials: E
authors.lastname: Brown
authors.forename: M
authors.initials: M
authors.lastname: Hill
authors.forename: H W
authors.initials: HW
authors.lastname: Kelly
authors.forename: D T
authors.initials: DT
authors.lastname: Loffert
authors.forename: H S
authors.initials: HS
authors.lastname: Nelson
authors.forename: S J
authors.initials: SJ
authors.lastname: Szefler
mesh_terms: D000336:Aerosols / Q000737:chemistry*; D001507:Beclomethasone / Q000737:chemistry; D004304:Dosage Forms; D005079:Excipients / Q000737:chemistry; D005446:Fluocinolone Acetonide / Q000031:analogs & derivatives / Q000737:chemistry; D009330:Nebulizers and Vaporizers; D010316:Particle Size; D014222:Triamcinolone Acetonide / Q000008:administration & dosage* / Q000737:chemistry
chemical_list: D000336:Aerosols; D004304:Dosage Forms; D005079:Excipients; D005446:Fluocinolone Acetonide; C007734:flunisolide; D014222:Triamcinolone Acetonide; D001507:Beclomethasone