Biomedical Engineering Reference
In-Depth Information
dry powders. h rough these nanoparticles the lungs can be targeted for
the drug delivery to specii c lung cells such as alveolar macrophages for the
treatment of tuberculosis [104].
Signii cant advances in medical aerosol development began in the 1950s
with a focus on the delivering of the asthma drugs directly to the lungs,
the target organ, thereby resulting in reduction in the amount of systemic
drug and their adverse ef ects [105]. Since mid-1800s nebulizers have been
used for delivering solutions of the drugs to target site, by generation of
aerosol droplets from liquid with the help methods such as ultrasonic or
air jet technology.
Recently, nanoscale aerosol vaccines have also been developed which
perfuse more throughout the respiratory tract and also increases the
amount of drug reaching to the target alveoli. Garcia ontreas
et al.
have
recently synthesized a particle system both micrometer and nanometer
dimensions for aerosolized delivery of the attenuated tuberculosis vaccine,
BCG. h e aerosol delivery of BCG encapsulated nanomicroparticles in
guinea pigs increased their resistance to tuberculosis infection, and gen-
eration of better immune protection than a standard parenteral BCG for-
mulation [106]. h e nanoparticulate delivery of aerosolized IFN-gamma
through the pulmonary route has been more ei cient new adjunct treat-
ment for tuberculosis [107].
Para-aminosalicyclic acid (PAS) is a tuberculostatic agent recently being
formulated into large porous particles for direct delivery into the lungs
via inhalation. h ese particles possess some optimized physical properties
for deposition through respiratory tract; the drug was loaded with 95%
by weight over 4 weeks at elevated temperatures. PAS concentrations were
measured in the plasma, lung lining l uid and homogenized whole lung
tissue. As a result the PAS get cleared within 3h from the lung lining l uid
and plasma. h e above experiment led to the conclusion that the inhala-
tion delivery of PAS help in the reduction of total dose delivered [108]. Dry
powder inhalation systems have also come into existence with a potential
of storing the drug in a dry state, which confers long term stability and
sterility. h e i rst type of dry powder inhalation system utilized the patients
breathing system for dispersing and delivering of the milled micron sized
particles. h e large geometric sized particles improved the dispersion
properties and higher lung deposition of the delivered dose (upto 59%)
[109]. Vyas formulated aerosolised liposomes with the incorporation of
RIF through a cast-i lm method. h e liposomes coated with the alveolar
macrophage-specii c ligands resulted in the more accumulation in alveolar
macrophages, thus maintaining high concentrations of RIF in the lungs,
even at er 24h [110].
