This document summarizes USP dissolution testing apparatus and procedures. It describes 7 different apparatus for testing dissolution of solid oral dosage forms including baskets, paddles, cylinders and flow-through cells. Key steps are outlined for each apparatus, including preparation of the dosage form sample, equilibrating the dissolution medium, operating conditions, sampling time points and procedures. Temperatures and rotations speeds are specified. The goal is to perform dissolution testing under standardized and reproducible conditions to evaluate drug release characteristics.

1. USP DISSOLUTION STUDIES

2. DISSOLUTIONA process in which a solid substance solubilizes in a given solvent. i.e. mass transfer from the solid surface to the liquid phase.USP DISSOLUTION APPARATUS• Apparatus 1 - Basket (37º)• Apparatus 2 - Paddle (37º)• Apparatus 3 - Reciprocating Cylinder (37º)• Apparatus 4 – Flow-Through Cell (37º)

3. • Apparatus 5 – Paddle over Disk (32º), Transdermal Delivery System, use paddle and vessel from Apparatus 2 with a stainless steel disk assembly to hold the transdermal on the bottom of vessel.• Apparatus 6, Cylinder (32º), Transdermal Delivery System, use Apparatus 1 except replace the basket shaft with a stainless steel cylinder element.• Apparatus 7, Reciprocating Holder, for transdermal delivery systems and also a variety of dosage forms

4. APPARATUS 1:The assembly consists of the following :A covered vessel, Transparent material, A motor,A metallic drive shaft, A cylindrical basket,The water bath permits the holding of temp inside vessel at 37±0.5 ̊C The vessel is a cylindrical with hemispherical bottom with dimension and capacity of.

5. The shaft is positioned so that its axis is not more than 2mm at any point from the vertical axis of the vessel and rotates smoothly and with out significant wobble.

6. Use 40mm mesh cloth.

7. A basket having a gold coating 0.0001 inch thick may be used. The dosage unit is place in a dry basket at the beginning of each test.The distance between the inside bottom of the vessel and the basket is maintained at 25± 2mm.APPARATUS 2The assembly from apparatus 1. Except paddle formed from a blade. a shaft is used as the stirring element The vertical center line of the blade is flush with the bottom of the shaft. The distance of 25±2 mm between the blade and the inside bottom of the vessel.

8. The paddle, blade and shaft may be coated with a suitably inert coating.

9. The dosage unit is allowed to sink to the bottom of the vessel before rotation of the blade.

10. A small, loose piece of nonreactive material such as wire helix may be attached to dosage units in order to prevent floating. DISSOLUTION MEDIUM If the dissolution medium is buffered solution adjust its pH within 0.05 unit of pH specified.TIME: If single time specification is given, the test may be concluded in a shorter period .

11. If two or more times are specified, specimen are to be withdrawn only at the stated times within a tolerance of ±2 % PROCEDURESPlace the stated volume of the dissolution medium in the vessel.

12. Equilibrate the dissolution medium to 37±o.5 ̊c

13. Place 1 tablet or 1 capsule in the apparatus.Operate the apparatus

14. Within the time interval, withdraw a specimen from zone midway between the surface of the dissolution medium and the top of the rotating basket or blade , not less than 1cm from vessel wall.

15. Replace the aliquots withdrawn for analysis with equal volume of dissolution medium at 37 ̊c. INTERPRETATION:

16. APPARATUS 3The assembly consists of: a set of cylindrical, flat-bottomed glass vessels; a set of glass reciprocating cylindrical; stainless steel fitting; screen; a motor and drive. The vessel is immersed in water bath holding temp at 37± 0.5 ̊

17. PROCEDURE:Place the stated volume of the dissolution medium in each vessel .

18. Equilibrate the dissolution medium to 37 + 0.5°

19. Place 1 dosage-form unit in each of the six reciprocating cylinders.

20. Operate the apparatus

21. During the upward and downward stroke, the reciprocating cylinder moves through a total distance of 9.9 to 10.1 cm