Abstract
Oral lichen planus (OLP) is an ongoing and chronic inflammatory disease affecting the mucous membrane of the oral cavity. Currently, the treatment of choice consists in the direct application into the buccal cavity of semisolid formulations containing a corticosteroid molecule to decrease inflammatory signs and symptoms. However, this administration route has shown various disadvantages limiting its clinical use and efficacy. Indeed, the frequency of application and the incorrect use of the preparation may lead to a poor efficacy and limit the treatment compliance. Furthermore, the saliva clearance and the mechanical stress present in the buccal cavity also involve a decrease in the mucosal exposure to the drug. In this context, the design of a new pharmaceutical formulation, containing a steroidal anti-inflammatory, mucoadhesive, sprayable and exhibiting a sustained and controlled release seems to be suitable to overcome the main limitations of the existing pharmaceutical dosage forms. The present work reports the formulation, optimization and evaluation of the mucoadhesive and release properties of a poloxamer 407 thermosensitive hydrogel containing a poorly water-soluble corticosteroid, dexamethasone acetate (DMA), threaded into hydroxypropyl-beta-cyclodextrin (HP-β-CD) molecules. Firstly, physicochemical properties were assessed to ensure suitable complexation of DMA into HP-β-CD cavities. Then, rheological properties, in the presence and absence of various mucoadhesive agents, were determined and optimized. The hydration ratio (0.218–0.191), the poloxamer 407 (15–17 wt%) percentage and liquid-cyclodextrin state were optimized as a function of the gelation transition temperature, viscoelastic behavior and dynamic flow viscosity. Deformation and resistance properties were evaluated in the presence of various mucoadhesive compounds, being the sodium alginate and xanthan gum the most suitable to improve adhesion and mucoadhesion properties. Xanthan gum was shown as the best agent prolonging the hydrogel retention time up to 45 min. Furthermore, xanthan gum has been found as a relevant polymer matrix controlling drug release by diffusion and swelling processes in order to achieve therapeutic concentration for prolonged periods of time.
Highlights
Lichen planus (LP) is a chronic inflammatory dermato-mucosal disease affecting most frequently the skin and oral mucosa areas, and involving the buccal mucous membrane
This paper describes for the first time the design of a novel thermosensitive hydrogel for buccal drug delivery intended to be sprayable, and exhibiting an optimized sol–gel transition temperature (30–32 ◦ C) that could allow the in situ gelation once administered in the oral cavity for the treatment of inflammatory diseases
We focused on the formulation process of hydrogels and the mechanism of dexamethasone acetate (DMA) encapsulation into HP-β-cyclodextrin molecules (CD) molecules and the rheological characterization of hydrogels and sustained-release
Summary
Lichen planus (LP) is a chronic inflammatory dermato-mucosal disease affecting most frequently the skin and oral mucosa areas, and involving the buccal mucous membrane. The pathology is called buccal or oral lichen planus (BLP or OLP). Pharmaceutics 2021, 13, 117 and origin of OLP are still unknown but various theories concerning its etiology have been proposed in the past [1,2]. That includes bacteria [3] or viral origin [4], neurogenic theories [5], environment or life-style factors [6] and other hypothesis associated with other diseases. The treatment of choice for the OLP consists of the use of topical steroids. The use of many topical steroid compounds is widely described in the scientific literature
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