The document discusses various dissolution testing methods and apparatuses. It describes the need for dissolution testing to estimate the rate of drug release from solid oral dosage forms. Common dissolution testing conditions involve simulating gastric and intestinal fluids at 37°C. Four common apparatuses are described for immediate-release and controlled-release drug products: the basket, paddle, reciprocating cylinder, and flow-through cell apparatuses. Limitations of the basket and paddle apparatuses are noted. Additional apparatuses for transdermal and topical dosage forms as well as the Franz diffusion cell are also summarized.

1. DAYANANDA SAGAR UNIVERSITY
DEPARTMENT OF PHARMACEUTICS
DISSOLUTION METHOD
Rajdulari
M. Pharma 2nd sem

3. NEED FOR DISSOLUTION TESTING DEVICE
 Solid drugs absorbed only from the solution .
 In vitro test – estimate amount of drug released per unit time.
 In vitro disintegration test not sufficient .
 In vitro dissolution test most reliable predictors of in vivo
performance.
 Dissolution - rate limiting factor.

4. COMMON CONDITIONS
 Simulated gastric and intestinal fluids – 37 deg
Celsius
 Fixed speed agitator
 Screen for separation of disintegrated particles
from the bulk

7. APPARATUS FOR CONTROLLED RELEASE
AND SUSPENSIONS
 APPARATUS I II AND III are for controlled release.
 APPARATUS II is for suspensions.
 There is also a Controlled Release Rotating Bottle Apparatus for controlled
release products.

8. Apparatus 1- Basket apparatus
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 .

9.  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.
 Use 40mm mesh cloth.
 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± 2m.
Drug product:
 Solids (mostly floating)
 Monodisperse (tablets)
 Polydisperse (encapsulated beads)

10. Apparatus 2- Paddle apparatus
 The 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.

14. Limitations of USP Apparatus 1and 2
 1. USP 2 (and USP1) Apparatus has plenty of HYDRODYNAMICS.
 2. Complicated 3-dimensional flow generated by the paddle.
 3. Significant impact of convective transport –Conditions used (50 – 100 rpm)
highly exaggerates flow in the GI.
 4. Use of solvents and surfactants non-native to GI.

15. APPARATUS 3- Reciprocating cylinder

18. APPARATUS 4- Flow through cell
 The assembly consists of a reservoir and a pump for the dissolution medium;
a flow-through cell; a water bath.
 The pump forces the dissolution medium upwards through the flow-through
cell.
 The pump has a delivery range between 240 and 960 mL per hour, with
standard flow rates of 4, 8, and 16 mL per minutes.
 The cell is immersed in a water bath and the temperature is maintained at
37 + 0.5°
 The apparatus uses a clamp mechanism and two O-rings for the fixation of
the cell assembly. Apparatus 4- Flow through cell

22. APPARATUS FOR TRANSDERMAL AND
TOPICAL DOSAGE FORM
 APPARATUS V VI AND VII are used for transdermal products.
 APPARATUS V AND VI are used for topical dosage forms.

23. APPARATUS 5- Paddle over disk

25. APPARATUS 6 -Cylinder

27. USP APPARATUS 7- Reciprocating holder

28. FRANZ DIFFUSION CELL
 It is a simple, reproducible test for measuring the drug release from creams,
ointments and gel.
The cell comprises of 2 parts:
 (a) sample holder containing 250 mg or 450 mg of sample.
 (b) reservoir of the diffusion cell.

29. REFERENCE
 1. Banakar V. U. and et. al. , pharmaceutical dissolution testing, markcel
deken, pg 4,16,57,136-137
 2. Remington, the science and practice of pharmacy, Mack pub. Co. , 19th
edition pg 594,601,602
 3. Brahmankar D.M. , Jaiswal S. , biopharmaceutics and pharmacokinetics a
treatise, Vallabh parashan, 2nd edition, pg 29-34
 4. www.dissolutiontech.com
 5. U.S. Pharmacopia,2008