Controlled Release of
Ionic Drugs from Complex Micelles
with Charged Channels
- Publication date
- Publisher
Abstract
Oral administration of ionic drugs generally encounters
with significant
fluctuation in plasma concentration due to the large variation of
pH value in the gastrointestinal tract and the pH-dependent solubility
of ionic drugs. Polymeric complex micelles with charged channels on
the surface provided us with an effective way to reduce the difference
in the drug release rate upon change in pH value. The complex micelles
were prepared by self-assembly of PCL-<i>b</i>-PAsp and
PCL-<i>b</i>-PNIPAM in water at room temperature with PCL
as the core and PAsp/PNIPAM as the mixed shell. With an increase in
temperature, PNIPAM collapsed and enclosed the PCL core, while PAsp
penetrated through the PNIPAM shell, leading to the formation of negatively
charged PAsp channels on the micelle surface. Release behavior of
ionic drugs from the complex micelles was remarkably different from
that of usual core–shell micelles where diffusion and solubility
of drugs played a key role. Specifically, it was mainly dependent
on the conformation of the PAsp chains and the electrostatic interaction
between PAsp and drugs, which could partially counteract the influence
of pH-dependent diffusion and solubility of drugs. As a result, the
variation of drug release rate with pH value was suppressed, which
was favorable for acquiring relatively steady plasma drug concentration
