ABSTRACT
Encapsulation of amoxicillin (AMC) with ethyl cellulose (EC) by a supercritical antisolvent process (SAS) was investigated. AMC microparticles obtained previously by an SAS process were used as host particles and EC, a biodegradable polymer used for the controlled release of drugs, was chosen as the coating material. In this work, a suspension of AMC microparticles in a solution of ethyl cellulose in dichloromethane (DCM) was sprayed through a nozzle into supercritical CO2. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and HPLC analyses were carried out. The effects of AMC:EC ratio, the initial polymer concentration of the solution, temperature and pressure on the encapsulation process were investigated. Although all the experiments led to powder precipitation, the AMC encapsulation was achieved in only half of the cases, particularly when the lower drug:polymer ratios were assayed. In general, it was observed that the percentages of AMC present in the precipitates were higher on increasing the AMC:EC ratio. In these cases composites rather than encapsulates were obtained. The in vitro release profiles of the resulting materials were evaluated in order to ascertain whether composites can be used as encapsulated systems for drug delivery systems.
Subject(s)
Amoxicillin/chemistry , Cellulose/analogs & derivatives , Drug Delivery Systems/methods , Cellulose/chemistry , Drug Delivery Systems/instrumentation , Particle SizeABSTRACT
The supercritical antisolvent (SAS) technique was used to prepare ethyl cellulose/methyl cellulose blends, two biocompatible polymers commonly used as drug carriers in controlled delivery systems. Ethyl cellulose is widely used as a drug carrier. The drug release of the delivery devices can be controlled to some extent by addition of a water-soluble or water swellable polymer, such as methyl cellulose. This leads to the solubility enhancement of poorly water-soluble molecules. SAS experiments were carried out at different operational conditions and microspheres with mean diameters ranging from 5 to 30 microm were obtained. The effect of CO(2) and liquid flow, temperature and pressure on particle size and particle size distribution was evaluated. The microspheres were precipitated from a mixture of dichloromethane (DCM) and dimethylsulfoxide (DMSO) (4:1 ratio). The best process conditions for this mixture were according to our study 40 degrees C and 80 bar.
Subject(s)
Cellulose/analogs & derivatives , Chromatography, Supercritical Fluid , Methylcellulose/chemistry , Polymers/chemical synthesis , Cellulose/chemistry , Chemical Precipitation , Dimethyl Sulfoxide/chemistry , Drug Carriers , Methylene Chloride/chemistry , Microspheres , Pressure , Solvents/chemistry , Surface Properties , Technology, Pharmaceutical/methods , TemperatureABSTRACT
The extraction of bioactive compounds from sunflowers (Helianthus annuus L.) with supercritical carbon dioxide has been studied. The samples were treated in four different ways and the effects of two factors (pressure and temperature) were investigated at 100, 500 bar and 35, 50 degrees C. The best yields were obtained using a high temperature and a high pressure (50 degrees C and 500 bar). The dry samples produced better extraction yields than the moist samples. The bioactivities of the extracts were compared for the samples treated in different ways. The best activity profiles were obtained for the moist samples extracted at 35 degrees C and 500 bar.
