Journal of Dental Research, Vol 68, 1285-1288, Copyright © 1989 by International & American Associations for Dental Research Online Journals
Development and in vitro evaluation of an intra-oral controlled-release delivery system for chlorhexidine
D. B. Mirth, A. Bartkiewicz, R. J. Shern and W. A. Little
Epidemiology and Oral Disease Prevention Program, National Institute of Dental Research, National Institutes of Health, Bethesda, Maryland 20892.
Copolymers of hydroxyethyl methacrylate (HEMA) and methyl methacrylate
(MMA) were prepared and used to fabricate a membrane-controlled
reservoir-type controlled-release delivery system for chlorhexidine that
should be suitable for intra-oral use. The reservoir of the system was
prepared by softening an 80:20 mixture of chlorhexidine diacetate and 50:50
HEMA:MMA copolymer with methyl ethyl ketone (MEK), and pressing standard
amounts of the resulting dough-like mixture into silicone rubber molds. A
membrane was applied to the reservoirs by rotating them through a solution
of 30:70 HEMA:MMA copolymer in MEK. The finished oval-shaped
controlled-release pellets were approximately 4.7 mm wide, 3.3 mm high, and
7.4 mm long, and contained 45.0 +/- 3.7 mg of chlorhexidine diacetate. The
mean in vitro release rate of chlorhexidine diacetate from the pellets into
37 degrees C water was 608 +/- 55 micrograms/24 h for days 2 through 11,
and 389 +/- 50 micrograms/24 h for days 15 to 30 of the test period. The
chlorhexidine released on day 30 was biologically active, as determined by
a serial dilution assay against Streptococcus mutans. The extended release
of biologically active chlorhexidine at a controlled rate from this system
suggests that it is worthy of further evaluation for the intra-oral therapy
of chlorhexidine-treatable oral infections in non-compliant and physically
or mentally compromised individuals.
