Abstract
This study describes the in vitro/ex vivo buccal release of chlorhexidine (CHX) from nine mucoadhesive aqueous gels, as well as their physicochemical and mucoadhesive properties: CHX was present at a constant 1% w/v concentration in the chemical form of digluconate salt. The mucoadhesive/gel forming materials were carboxymethyl- (CMC), hydroxypropylmethyl- (HPMC) and hydroxypropyl- (HPC) cellulose, alone (3% w/w) or in binary mixtures (5% w/w); gels were tested for their mucoadhesion using the mucin method at 1, 2 and 3% w/w concentrations. CHX release from different formulations was assessed using a USP method and newly developed apparatus, combining release/permeation process in which porcine mucosa was placed in a Franz cell. The combination of HPMC or HPC with CMC showed slower drug release when compared to each of the individual polymers. All the systems proved suitable for CHX buccal delivery, being able to guarantee both prolonged release and reduced transmucosal permeation. Gels were compared for the release of previously studied tablets that contained Carbopol and HPMC, alone or in mixture. An accurate selection and combination of the materials allow the design of different pharmaceutical forms suitable for different purposes, by simply modifying the formulation compositions.
Highlights
Many pharmaceutical researchers have focused on formulations enabling drug targeting and prolongation of the therapeutic effect in the oral cavity; protection of the drug from degradation in the adverse biologic environment was an additional focus
These requirements can be fulfilled by a suitable mucoadhesive formulation inside the buccal cavity: conventional dosage forms, maintain their effects in this cavity for a significant period of time with difficulty, because they are very removed by salivation, temperature, tongue movement, and swallowing
Important limitations, concerning the size of mucoadhesive tablets, whose thickness must be limited to about 1 mm and which must be soft enough to be acceptable to patients and not cause irritation [3], suggest the use of mucoadhesive films or gels that represent an alternative to solid forms, since they can offer a larger and softer surface area of release in the buccal area for an extended period of time, due to their viscosity [4,5] and add compliance in terms of flexibility and comfort
Summary
Many pharmaceutical researchers have focused on formulations enabling drug targeting and prolongation of the therapeutic effect in the oral cavity; protection of the drug from degradation in the adverse biologic environment was an additional focus. These requirements can be fulfilled by a suitable mucoadhesive formulation inside the buccal cavity: conventional dosage forms, maintain their effects in this cavity for a significant period of time with difficulty, because they are very removed by salivation, temperature, tongue movement, and swallowing. Adhesive films and laminated patches, used as buccal delivery systems, present some disadvantages associated with the solvent casting method, such as environmental concerns, long processing times, and high costs [6] and appear more useful to deliver drugs directly to a mucosal membrane
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