Adopted in 1970 the rotating basket method of dissolution testing was the first official method. It essentially consists of an approximately 1 inch (25.4mm) x 1 3/8 inch (34.925mm) stainless steel, 40-mesh wire basket rotated at a constant speed between 25 and 150rpm. This method is now called Apparatus 1 (or method 1). The apparatus consists of a metallic drive shaft connected to the cylindrical basket. The basket is positioned inside s vessel made of glass or other inert, transparent material. The vessel contents are kept at a constant temperature by being placed inside a water bath or heating jacket. The solution in the vessel is stirred smoothly by the rotating basket. The USP Apparatus 1 requires a 40-mesh screen unless otherwise specified in the monograph. Other meshes can be used to solve individual problems.

Useful for

Advantages

Standard Volume

Gold Plated Basket

Pure gold plating up to 2.5um thickness is allowed by the USP for use in acid media or where the active drug reacts with the plain steel basket. If gold is used, the shaft as well as the basket should be coated. Uncoated baskets deteriorate from contact with acid and they become less rugged and are more likely to distort during assembly on the drive rod.

Unique Identification

All baskets and shafts should be unique identified, documented, and kept in the same position in the same test assembly for all dissolution runs.