The Application of Mechanical Aerosol Delivery Systems in an in vitro Model of Mechanically Ventilated Neonates
Touraj Ehtezazi and Mark. A. Turner
Affiliation: School of Pharmacy and Biomolecular Sciences, Liverpool John Moores University, Liverpool; UK.
Delivery of medication to the neonatal lung using current methods is inefficient. Aerosols offer one way to improve
delivery to small airways. In this in vitro work, aerosol delivery by using a micropump or a rotary valve has been
evaluated in a model of the neonatal setting with a pressurised metered dose inhaler plus spacer outside of the inspiratory
limb. Drug depositions were assessed by spectrophotometric analyses. Drug lung deposition was increased by adjusting
the rotary valve for co-ordination between the inhalation and aerosol delivery, but this intermittent mode decreased the
aerosol delivery by using the micropump. Also, decreasing the volume of spacer decreased drug deposition in test lungs
by using the micropump system. At the optimum conditions, the rotary valve aerosol delivery system delivered
3.68±0.91% of the Qvar nominal dose to the test lungs, and this was 2.34±0.01% for the micropump system. In conclusion,
the rotary valve aerosol delivery system provided higher amounts of drug particles to the test lungs compared to the
micropump system. The advantages of these methods were that the humidity in the ventilation circuit did not affect the
aerosol particles in the spacer. Further optimisation is required to improve aerosol deposition in the test lungs. The article
has also a short section of recent patents relevant to aerosol delivery.
Keywords: Aerosol Delivery, humidity, neonates, pressurised metered dose inhalers, spacer.
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