Design and evaluation of an automated system for in vitro dissolution testing utilizing a high-pressure liquid chromatographic multiport switching valve.

An automated system for the simultaneous dissolution testing of six samples was developed consisting of four basic units: dissolution vessels and stirring unit, a peristaltic pump, a rotary stream multiport switching valve and programmer, and a UV spectrophotometer with recorder. Among the major advantages of such a system are: (a) paddle or basket stirring with variable speed is used, (b) the tablet or capsule (wire coil required) locates reproducibly at the bottom of a round-bottom reaction flask when utilizing paddle-type stirring, (c) a USP basket for tablet or capsule dissolution testing can be used, (d) continuous or intermittent sampling is possible, (e) the flow system readily adapts to UV-visible detector or fluorescence spectroscopy, (f) the system readily adapts to automated determination of the intrinsic dissolution of a material, and (g) the cost is low because of the multiport switching valve and inexpensive UV monitor required. Studies were performed using this apparatus to demonstrate the response characteristics of the system, its reproducibility, potential problems, and precautions required. This dissolution system was used to determine the dissolution characteristics of a new steroid tablet formulation, including a formulation and lot demonstrated to be bioavailable.