Page 276 - Pharmaceutics IV (02-06-01305)
P. 276
3/30/24
Particle size
Particle size is a critical quality control parameter in case of
powder aerosols, why?
To solve this problem powder the particle size of powder inhalations should be
inhalers usually incorporate a sufficiently small to maximize administration to the
deeper regions of the lungs.
means of breaking up any
aggregates that form; either a Small particles however, are associated
mesh or propeller driven by with a large surface area. To minimize the
resulting large surface free energy,
air flow particles tend to aggregate and adhere to
surface with which they come in contact.
• Hygroscopic particles will increase in
size when water vapour is absorbed.
• For this reason, powder inhalations are
less efficient than pressurized aerosols.
Prof Alyaa Ramadan, ceutics, AU
59
Aerosol deposition in the
patient’s airways by p size
Particles >10 μm Particles with sizes While particles <5
settle in the upper ranging from 5 to μm penetrate the
respiratory tract 10 μm reach the
(i.E. Nose, mouth, trachea, bronchi alveoli.
throat and larynx), and bronchioles,
Accordingly, the control of the particle or
droplet size of the generated aerosol is
necessary to produce medicaments with the
desired and specific properties
Prof Alyaa Ramadan, ceutics, AU
60
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