Dissolution Apparatus: Apparatus 1 & 2

Apparatus: 1 (Basket apparatus)

The assembly consists of the following a covered vessel made up of glass, or other transparent material, a cylindrical basket. The vessel is partially immersed in a suitable water bath of any convenient size that permits holding the temp. Inside the vessel at 37 +- during the test and keeping the bath fluid in constant smooth motion. No part of the assembly including the environment in the assembly is placed, contributes significant motion, agitation, or vibration beyond that due to the smoothly rotating stirring element apparatus that permits observation of rotating stirring element. Apparatus that permits observation of the specimen & stirring element during the test is preferable. The vessel is cylindrical, with a hemispherical bottom, it is 160 – 175 mm high, it’s inside diameter is 98-106 mm, and its nominal capacity is 1000 ml .a fitting cover may be used to retard evaporation. The shaft is positioned so that its axis not more than 2 mm at any point from the vertical axis of the vessel and rotate smoothly. A speed regulatory device is used that allows the shaft rotation speed to be selected and individual monograph the individual monograph, within range of 4%.

• Shaft and basket component of starring elements fabricated of stainless steel, type 316 or equivalent to the specification shown individual monograph figure.
• Unless and otherwise specified in the individual monograph monograph use 40 mesh cloth. A basket having a gold coating 0.0001-inch (2.5micrometer) thick may be used. The dosage unit is placed in a dry basket at beginning of each test, the distance between the inside bottom of the vessel and basket maintained 25 ± 2 mm during test.

Weaknesses of Basket Method

• Poor mechanical stability.
• Hindered visual inspection.
• Disintegration-dissolution interaction (slower disintegration keeps the dosage unit in a site of higher agitation, thus increasing dissolution).
• Poor homogeneity of the bulk fluid due to insufficient stirring or agitation.
• Sensitivity against external vibration, eccentricity, and the presence of baffles such as thermometer or sampling tube.
• Inconvenience for cleaning the set-up after testing. 

Apparatus 2   (Paddle apparatus).

Use the assembly from apparatus 1, except that a paddle formed a blade and a shaft is used as stirring element the shaft is positioned so that its axis is not more than 2mm at any point from the vertical axis of vessel and rotates smoothly without significant wobbling .the blade passes through the diameter of shaft. The paddle conforms to specification shown in the figure .the distance of 25 +2mm between the blade and inside bottom of the vessel is maintained during the test. The metallic blade and shaft comprising single entity. That may be coated with the suitable material. The dosage form is allowed to sink to bottom of vessel before rotation of blade started. A small loose piece of nonreactive material such as not more than few turn of the wire helix may be attach to dosage unit that would otherwise floats.

Weaknesses of Paddle Method

•         Problems with floating dosage form products.

•         Use of spiral for holding capsules is subject to variability with operators.

The phenomenon of cone formation that results from nondispersioning of disintegrated tablets can lead to nonreproducibility of test.

Calibration of the dissolution apparatus

Dissolution Calibrator for USP Apparatus 1 and 2

• Prednisone Tablet
• Prednisone Ref. Std.
• Salicylic Acid Tablets
• Salicylic Acid Ref. Std 

Comparison of Apparatus 1 & 2

	Ph.Eur.2	USP 24	Ph.J.12
VESSEL
Height	168+-8	160-175	160-175
Internal diameter	102+-4	98-106	98-106
Paddle
Shaft diameter	9.75+-0.35	9.4-10.1 (before coating)	9.75+-0.35
BLADES
Upper chord	74+-0.5	74+-0.5	74+-0.5
Lower chord	42	42+-1	42+-1
Height	19	19+-0.5	19+-0.5
Radius of the disk which the blade is cut out	41.5	41.5+-1	41.5+-1
Radius upper corners	1.2	1.2	1.2
Thickness	4.0+-1	4.0+-1	4.0+-1
Positioning of stirring device
Distance between inside of bottom of vessel and blade	25+-2	25+-2	25+-2
Basket
Shaft diameter	9.75±0.35 6.4+-0.1	6.3-6.5 9.4-10.1	9.75±0.35 6.4+-0.1
Screen
Wire diameter	0.254	0.254(0.001inch)or 0.016 inch	No.36 wire gauze
Opening	0.381	0.381	0.425
Height of screen	27+-1	27+-1	27+-1
Total height of basket	36.8+-3	36.8+-3	36.8+-3
Internal diameter of basket	20.2+-1	20.2+-1	20.2+-1
External diameter of ring	25.4+-3	25.4+-3	25.4+-3
Vent hole dia.	2	2	2

Dissolution of Extended release articles

• Apparatus 1 & 2 are used for dissolution testing
• Apparatus, Apparatus Suitability test, Dissolution medium & procedure are same as Apparatus 1 and 2.

Interpretation:- 

• quantities dissolved should conform to acceptance table
• continue testing 3 level unless results conform at either L1 or L2
• limits on the amounts of active ingredients dissolved are expressed in terms of the percentage of labeled content

Level	No.Tested	Criteria
L1	6	No individual value lies outside each of the stated range & no individual value are less then the stated amount at final test time
L2	6	The average value of 12 units (L1+L2) lies within each of the stated ranges & is not less than the stated amount at the final test time, none is more then 10% of labeled content outside each of the stated ranges & none is more than 10% of labeled content below the stated amount at final test time.
L3	12	The average value of 24 units (L1+L2+L3) lies within each of the stated ranges & is not less than the stated amount at final test time, not more than two of the 24 units are more than 10% of the labeled content outside each of the stated ranges, not more than 2 of the 24 units are more than 10% of labeled content below the stated amount at final test time & none of the units is more than 20% of labeled content outside each of the stated ranges or more than 20% of labeled content below the stated amount at final test time.