Improved Method for Evaluating Encapsulated Drug Delivery

摘要

The current United States Pharmacopeia (USP) test for evaluating encapsulated drug disintegrationis limited and does not specify the initial disintegration time. This national test gives limited information onthe disintegration process of encapsulated drugs. Thermal Mechanical Analysis (TMA) has been developedto measure the rate and initial time of drug capsule disintegration. The TMA monitors the physicaldimension of the formulated drug capsule as a function of time;temperature;applied stress and pH. Theresult of this test will meet USP specifications. This method can be used to measure the expansion;swelling;shrinking or disintegration of the encapsulated drug in a specified fluid.The focus of this study is to improve the Isothermal Thermal Mechanical Analysis (IsoTMA)method to measure the drug delivery of encapsulated drugs. The precision of the method along with theeffect of pH and temperature on the rate of delivery was determined. A new sample holder for securing thecapsule was developed. A quartz probe with a 6mm outer diameter was employed in this study to bettermeasure a larger sampling of the capsule. The repeatability of the IsoTMA was assessed. A new timelapsedphotomacrography test with thermal control in a Pyrex beaker was developed based on visual andmacroscopic variations in the capsule. The drug used for this study was the 500mg Amoxicillin capsule.Both the IsoTMA and the macro-visual methods measure dimensional stability of the drug capsule as it isimmersed in various solutions. The temperature was varied from 25oC to 37oC and the pH from 3 to 7.Graphical representations of these dimensional changes as determined by both methods were created andcompared.