ABSTRACT
Orlistat is locally acting inhibitor of gastrointestinal lipases which has been developed for the treatment of obesity. The present study was designed with the intent to formulate orlistat in a different way compared to the current practice and investigate its inhibition of gastrointestinal lipases. Orlistat is considered as a technologically problematic and unmanageable substance because of waxy nature, low melting point and low chemical stability. The manuscript presents the critical issues regarding engineering of its nanosuspension with controlled particle size by melt emulsification and high pressure homogenization. In order to formulate dry product, lactose was dissolved in nanosuspension as filler and spray drying has been performed for obtaining the final powder product. Laser diffraction, scanning electron microscopy and atomic force microscopy have been used for orlistat nanosuspension characterization, dissolution studies and lipase inhibition studies were performed to characterize the in vitro efficacy of formulated orlistat. The advantage of selected technological procedures is nanosized orlistat with elevated in vitro dissolution rate in comparison to raw drug, physical mixture and marketed product. Furthermore, nanosuspension demonstrated significantly higher in vitro lipase inhibition in comparison to references. To conclude, the results show new technological solution and remarkable increase of pharmacological effect which could potentially lead to decreasing the dose and consequently dose dependent side effects.
Subject(s)
Anti-Obesity Agents/chemistry , Anti-Obesity Agents/pharmacology , Enzyme Inhibitors/chemistry , Enzyme Inhibitors/pharmacology , Lactones/chemistry , Lactones/pharmacology , Lipase/antagonists & inhibitors , Chemistry, Pharmaceutical , Drug Compounding , Kinetics , Lactose/chemistry , Microscopy, Atomic Force , Microscopy, Electron, Scanning , Nanoparticles , Nanotechnology , Orlistat , Powders , Solubility , Surface Properties , Technology, Pharmaceutical/methodsABSTRACT
Drugs with low aqueous solubility and high permeability (BCS class II) present a high proportion of all drugs. This study examines the critical issues regarding engineering of a nanosuspension tailored to increase drug dissolution rate and its transformation into dry powder suitable for tabletting. Nanosuspensions of celecoxib, a selective COX-2 inhibitor with low water solubility, were produced by the emulsion-diffusion method using three different stabilizers (Tween) 80, PVP K-30 and SDS) and characterized by particle size analysis, dissolution testing, scanning electron microscopy imaging, differential scanning calorimetry and X-ray powder diffraction. Spray-dried nanosuspension was blended with microcrystalline cellulose, and compressed to tablets, and their tensile strength, porosity and elastic recovery of tablets were investigated. The selection of solvent and stabilizers is critical, firstly to achieve controlled crystallization and size, and secondly to increase the wettability of the hydrophobic drug. The crystalline nano-sized celecoxib alone or in tablets showed a dramatic increase of dissolution rate and extent compared to micronized. SEM images showed that the nanoparticle morphology was influenced by the choice of stabilizers. Celecoxib nanosuspension stabilized with PVP K-30 and SDS showed advantages over Tween 80 due to sticking of the dried product and unexpected changes observed on DSC curves. Markedly lower compaction forces are needed for nano-sized compared to micro-sized celecoxib to produce tablets of equal tensile strength.
