Preparation and in vitro characterization of carvacrol pellets by combination of liquisolid technique and extrusion-spheronization

Carvacrol is one of the main pharmacologically active components of Thymus vulgaris essential oil, which has shown several therapeutic effects. Because of liquid nature of the carvacrol, the formulation of the drug is challenging. Liquisolid technique is a method for converting a liquid drug into a solid system. The aim of this study is to combine the liquisolid approach and extrusion-spheronization technique to produce pellets with desirable physico-mechanical, stability and release properties. Three different methods were used for preparation of liquisolid matrix of carvacrol using PVP K30, stearic acid and Aerosil. The matrices were utilized for preparation of pellets by extrusion-spheronization method. The pellets were characterized for size (sieve analysis), shape factors (image analysis), mechanical strength, chemical interactions (FTIR), thermal behavior (DSC), carvacrol content, release rate (dissolution test) and stability. The results showed that by using suitable composition of liquisolid matrix and granulation fluid, pellets with desirable size and shape and mechanical properties could be produced. PVP-based pellets had higher mechanical strength, slower release rate and improved content and stability compared to stearic acid or Aerosil-based pellets. The carvacrol ratio has considerable effect on release properties of the pellets. Overall results revealed the feasibility of preparing desirable pellets containing carvacrol with acceptable content, stability and release properties, which can be administered as hard gelatin capsules. PVP-based pellets were the most appropriate formulation according to evaluation tests. [Display omitted]