Nanoparticles for controlled delivery and sustained release of chlorhexidine in the oral environment

Chlorhexidine (CHX) is in widespread use as a topical antimicrobial agent. Within the field of oral medicine, it is used in the prevention of ventilator-associated pneumonia as well as in the treatment of oral candidosis and microbial-associated lichenoid reactions. The objective of this study was to develop a strategy for controlled, sustained topical delivery of CHX using nanoparticle technology.

Chlorhexidine was applied to hydroxyapatite, selected as a tooth analogue, as conventional CHX digluconate solutions and as aqueous suspensions of CHX hexametaphosphate nanoparticles with total CHX concentrations of 1, 2.2 and 5 mM. Soluble CHX release from the treated hydroxyapatite was monitored over a period of 7 days.

A repeated-measures ANOVA with post hoc LSD test indicated that CHX release was 2-3× greater, and sustained for longer, when CHX was delivered as CHX hexametaphosphate nanoparticles than in aqueous solution with 2.2 and 5 mM CHX (P = 0.020 and 0.013, respectively), but there was no statistically significant difference at 1 mM CHX (P = 0.172).

Chlorhexidine hexametaphosphate nanoparticles increased both the local dose and duration of soluble CHX delivery when applied to hydroxyapatite surfaces. This may provide a means to deliver a sustained dose of CHX with less frequent interventions.