Dissolution study of active pharmaceutical ingredients using the flow through apparatus Usp 4

Abstract

The flow through system has been employed for many years in the testing of different dosage forms such as tablets and capsules.The flow through cell is the method of choice for extended release and poorly soluble products.Thanks to the specific powder cell it is possible to characterize a drug substance with respect to its rate of dissolution. The aim of this work was to compare the biopharmaceutical properties of different batches of a drug substance using the dissolution rate determined using the flow through apparatus. The apparatus consists of a reservoir of dissolution medium,a pump that forces the dissolution medium upwards through the flow through cell and a cell specifically designed for powders,mounted vertically with a filter system preventing escape of undissolved particles. In the flow through method the test sample is located in a small-volume cell through which solvent passes at a temperature of 37 °C. Five batches of theophylline with a mean diameter of 128 μm to 673 μm and two batches of acetylsalicylic acid,either fine particles or needles,were studied.The experiment was conducted using six cells in an open system. Through the results obtained, the relationship between particle size distribution and dissolution rate has been verified.The rate of dissolution is faster for drug with low particle size and a higher surface area.The experimental parameters such as flow rate have been studied and optimized. The overall results demonstrate that it is possible to characterize the biopharmaceutical qualities of active pharmaceutical ingredients using the flow through cell.The method is reliable, reproducible and discriminating. It can easily be used to compare drugs with different particle size distributions.