Formulation and in-vitro characterization of herbal licorice gel for periodontal therapy

Abstract

Periodontal diseases are inflammations of the periodontium caused by certain microorganisms, leading to progressive destruction of the periodontal ligament and alveolar bone. Conventional medications have limitations such as extrinsic tooth discoloration, altered taste sensation, and the development of bacterial resistance. Licorice is an herb with glycyrrhetinic acid (GA) as its main active component. GA has antimicrobial, anti-inflammatory and antioxidant activity. There is limited evidence for the preparation and in vitro evaluation of licorice extract as a topical drug in periodontology. The aim of this study was the formulation and in vitro characterization of a controlled-release gel containing licorice extract that can be used as a topical agent in periodontal therapy. An in vitro study was conducted in which an ethanolic extract of licorice was prepared. The local drug delivery gel was formulated with the specified minimum inhibitory concentration of Glycyrrhiza glabra using Carbopol 940 polymer. In vitro characterization of the formulated gel was done in terms of physical appearance, determination of pH, squirtability, drug content, gelation temperature and time, viscosity, mucoadhesive force, in vitro drug release, thermodynamic stability and X-ray diffraction analysis. The licorice gel formulation was thermodynamically stable, mucoadhesive, and sprayable. It also released the drug slowly for up to 48 hours. The incorporation of licorice extract into a polymeric gel base exhibits good physicochemical properties, adequate mucoadhesiveness, and controlled drug release. Thus, it is a potential herbal extract for local drug delivery that can be used to improve the therapeutic results of scaling and root planning.