Dissolution Testing of Acetaminophen Suspension Using Dialysis Adapter in Flow-Through Apparatus: A Technical Note

Dissolution testing is an important tool during drug development, characterization, and quality control of both immediate- and controlled-release formulations. It has been used for evaluating candidate formulations and for understanding possible risks related to specific gastrointestinal factors, potential for dose dumping, food effects on bioavailability, and interaction with excipients (1,2). Recently, dissolution testing has been increasingly used to test dosage forms such as suspensions, soft gelatin capsules, creams and transdermal systems. To test these special dosage forms, special accessories are sometimes required. SOTAX Inc. recently introduced a dialysis adapter for release testing of solution and semisolid formulations. This device, as shown in Fig. 1, facilitates the use of dialysis tubing to sequester a sample in the center of the USP 4 standard 22.6 mm flow cell. The applications with this dialysis adapter are mainly for in vitro release testing of dispersed dosage forms. One publication by Burgess’ group using this method compared dexamethasone release from extruded and non-extruded liposomes (3). Results showed that the USP apparatus 4 method with this dialysis adapter could discriminate between solution, suspension, and liposome formulations of dexamethasone. Fig. 1 Dialysis adapter from Sotax Inc The objective of this study was to evaluate this new dialysis adapter. An acetaminophen suspension drug product and various concentration acetaminophen solution samples were used to compare the flow-through method with and without the dialysis adapter, as well as to compare two different sizes of dialysis membranes. Other parameters such as flow rate, dissolution media, and medium ionic strengths were also studied.