title: Preparation of carbamazepine-Soluplus solid dispersions by hot-melt extrusion, and prediction of drug-polymer miscibility by thermodynamic model fitting.
abstract: Hot-melt extrusion (HME) is a dust- and solvent-free continuous process enabling the preparation of a variety of solid dosage forms containing solid dispersions of poorly soluble drugs into thermoplastic polymers. Miscibility of drug and polymer is a prerequisite for stable solid dispersion formation. The present study investigates the feasibility of forming solid dispersions of carbamazepine (CBZ) into polyethyleneglycol-polyvinyl caprolactam-polyvinyl acetate grafted copolymer (Soluplus) by hot-melt extrusion. Physicochemical properties of the raw materials, extrudates, co-melted products, and corresponding physical mixtures were characterized by thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), attenuated total reflectance infrared (ATR-FTIR) spectroscopy and hot stage microscopy (HSM), while miscibility of CBZ and Soluplus was estimated on the basis of the Flory-Huggins theory, Hansen solubility parameters, and solid-liquid equilibrium equation. It was found that hot-melt extrusion of carbamazepine and Soluplus is feasible on a single-screw hot-melt extruder without the addition of plasticizers. DSC analysis and FTIR spectroscopy revealed that a molecular dispersion is formed when the content of CBZ does not exceed ∼5% w/w while higher CBZ content results in a microcrystalline dispersion of CBZ form III crystals, with the molecularly dispersed percentage increasing with extrusion temperature, at the risk of inducing transformation to the undesirable form I of CBZ. Thermodynamic modeling elucidated potential limitations and temperature dependence of solubility/dispersibility of carbamazepine in Soluplus hot-melt extrudates. The results obtained by thermodynamic models are in agreement with the findings of the HME processing, encouraging therefore their further application in the HME process development.
authors: Department of Pharmaceutical Technology and Cosmetology, University of Belgrade, Belgrade, Serbia. jelena.djuris@pharmacy.bg.ac.rs
authors: Jelena
authors: J
authors: Djuris
authors: Ioannis
authors: I
authors: Nikolakakis
authors: Svetlana
authors: S
authors: Ibric
authors: Zorica
authors: Z
authors: Djuric
authors: Kyriakos
authors: K
authors: Kachrimanis
mesh_terms: D002220:Carbamazepine / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D002626:Chemistry, Pharmaceutical / Q000379:methods*; D005544:Forecasting; D006358:Hot Temperature; D011092:Polyethylene Glycols / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D011108:Polymers / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D011145:Polyvinyls / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D013816:Thermodynamics
chemical_list: D011108:Polymers; D011145:Polyvinyls; C572167:polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer; D002220:Carbamazepine; D011092:Polyethylene Glycols