Abstract
Drug-containing polymer nanoparticles are submicron-sized
particles consisting of drug and stabilising or
functional polymer. In this experimental study,
methacrylic polymer nanoparticles with and without
incorporated model drug were prepared using a novel
method, namely, aerosol flow reactor method. This method
involves first preparing a solution containing the drug
and the polymer, followed by spraying the solution as
nanosized droplets into a carrier gas stream, then drying
the nanoparticles in a tubular laminar flow reactor tube,
and finally collecting the nanoparticles. Model polymers
used in this study were Eudragit L, Eudragit E, and
Eudragit RS, which are commonly used methacrylic polymers
in the pharmaceutical industry. Model drugs studied were
beclomethasone dipropionate, ketoprofen, and naproxen.
Various properties of the prepared nanoparticles were
studied, such as particle size and size distribution,
morphology, crystallinity, thermal properties, drug
content, and drug release. It was found that this method
could be used to produce amorphous, spherical,
homogeneous matrix-type drug-polymer nanoparticles. The
size of the particles was adjusted between 90 and 200 nm
by the concentration of the solution. The morphology of
the particles varied as a function of the properties and
composition of the starting solution.
The nanoparticles were collected as dry powders, but the
stability of the powders in an amorphous form was found
to be dependent on the interactions between the drug and
the polymer. When the amount of the drug in the
nanoparticles was below the solubility limit of the drug
in the polymer, the amorphous nanoparticles were found to
be stable and no crystallisation of the drug took place.
When the amount of the drug was larger than the
solubility limit, large crystalline structures were
formed due to crystallisation of the drug. The
crystallisation was also dependent on the thermal
properties of the drug, as amorphous nanoparticles
consisting of a drug having a high glass transition
temperature could be collected at room temperature. A low
glass transition temperature of the drug led to
crystallisation of the drug at ambient conditions, when
the drug amount in the nanoparticles was larger than the
solubility limit. Drug release from the nanoparticles
could be modified by using polymers having specific
solubility properties.
Original language | English |
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Qualification | Doctor Degree |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 3 Jun 2005 |
Place of Publication | Espoo |
Publisher | |
Print ISBNs | 951-38-6443-X |
Electronic ISBNs | 951-38-6444-8 |
Publication status | Published - 2005 |
MoE publication type | G5 Doctoral dissertation (article) |
Keywords
- methacrylic polymer nanoparticles
- preparation of drug nanoparticles
- aerosol flow reactor method
- drug release
- solubility properties
- particle size
- morphology
- crystallinity
- thermal properties
- drug content