Mucoadhesive vaginal tablets as veterinary delivery system for the controlled release of an antimicrobial drug, acriflavine

The aim of the study was the
development of mucoadhesive vaginal tablets
designed for the local controlled release of acriflavine,
an antimicrobial drug used as a model. The tablets
were prepared using drug-loaded chitosan
microspheres and additional excipients
(methylcellulose, sodium alginate, sodium
carboxymethylcellulose, or Carbopol 974). The
microspheres were prepared by a spray-drying
method, using the drug to polymer weight ratios 1:1
and 1:2 and were characterized in terms of
morphology, encapsulation efficiency, and in vitro
release behavior, as MIC (Minimum Inhibitory
Concentration), MBC (Minimum Bacterial
Concentration), and killing time (KT). The tablets were
prepared by direct compression, characterized by in
vitro drug release and in vitro mucoadhesive tests. The
microparticles have sizes of 4 to 12 μm; the mean
encapsulation yields are about 90%. Acriflavine,
encapsulated into the polymer, maintains its
antibacterial activity; killing time of the encapsulated
drug is similar to that of the free drug. In vitro release
profiles of tablets show differences depending on the
excipient used. In particular Carbopol 974, which is
highly cross-linked, is able to determine a drugcontrolled
release from the matrix tablets for more than
8 hours. The in vitro adhesion tests, carried out on the
same formulation, show a good adhesive behavior.
The formulation containing microspheres with drug to
polymer weight ratios of 1:1 and Carbopol 974 is
characterized by the best release behavior and shows
good mucoadhesive properties. These preliminary data
indicate that this formulation can be proposed as a
mucoadhesive vaginal delivery system for the
controlled release of acriflavine.