Dissolution Test (U.S.P.): Two set of apparatus: Apparatus-1: A single tablet is placed in a small wire mesh basket attached to the bottom of the shaft connected to a variable speed motor. The basket is immersed in a dissolution medium (as specified in monograph) contained in a 100 ml flask. The flask is cylindrical with a hemispherical bottom. The flask is maintained at 37±0.5 0 C by a constant temperature bath. The motor is adjusted to turn at the specified speed and sample of the fluid are withdrawn at intervals to determine the amount of drug in solutions.

Apparatus-2: It is same as apparatus-1, except the basket is replaced by a paddle. The dosage form is allowed to sink to the bottom of the flask before stirring. For dissolution test U.S.P. specifies the dissolution test medium and volume, type of apparatus to be used, rpm of the shaft, time limit of the test and assay procedure for. The test tolerance is expressed as a % of the labeled amount of drug dissolved in the time limit.

Procedure: 1. Put one tablet into the cylindrical basket 2. The basket is immersed into dissolution medium (water, simulated gastric or intestinal) at 37 ◦C 3.Operate the apparatus at 50 rpm and take samples from the dissolution medium at interval time (25 ml every 10 minutes for 30 minutes) 4.Pipette 2 ml of the sample and complete up to 50 ml of 0.1 N H2SO4 in a conical flask.

7. Measure the absorbance by using a spectrophotometer at 228 nm and apply the following equations: 6. Plot D% against time C = Ab x K x dilution factor x Dissolution medium C = Ab x 0.02 x 25 x 500 Then find, D% = C mg/ Label content x 100 Where, C = concentration, Ab. = Absorbance, K = Constant, D% = percentage of dissolution, Label content = Amount of active ingredient present in the tablet

Acceptance criteriaNo. of tested tabStage Each unit is not less than Q+5%6 TABS1 Average of 12 units (S1+S2) is equal to or greater than Q, and no unit is less than Q – 15% 6 TABS2 Average of 24 units (S1+S2+S3) is equal to or greater than Q, not more than 2 units are less than Q – 15% and no unit is less than Q – 25% 12 TABS3 Q: It is the amount of dissolved active ingredient, expressed as a percentage of the labeled content (C mg)

Paracetamol … measure at nm Aspirin……………………… nm Indomethacin ……………….578 nm Ibuprofin ……………………. 230 nm