1. A
Presentation
On
Dissolution study of solids and suspension
By
Mr. Ghodake Chaitanya A.
Under the Supervision of
Mr. N. A. Guajrathi
Assistant Professor
P.S.G.V.P.M’s
DEPARMENT OF PHARMACEUTICS
SHAHADA, DISTRICT- NANDURBAR
MAHARASHTRA.
2011-2012

2. CONTENTS
• Introduction
• Theories of Drug Dissolution
• Dissolution of Solids
• Dissolution of Powder
• Dissolution of Capsules
• Dissolution of Tablets
• Dissolution of Suspension
• Dissolution of Suppositories
• References
2

3. Definition-
• Dissolution is a process in which a solid substance
solubilizes in a given solvent i.e. mass transfer from
the solid surface to the liquid phase.
• Rate of dissolution is the amount of drug substance
that goes in solution per unit time under standardized
conditions of liquid/solid interface, temperature and
solvent composition.
3

4. Theories of Drug Dissolution
I. Diffusion layer model/Film Theory
II. Danckwert’s model/Penetration or surface renewal
Theory
III. Interfacial barrier model/Double barrier or Limited
solvation theory.
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5. I. Diffusion layer model/Film Theory :-
Noyes whitney equation
5
dc/dt = k (Cs- Cb)

6. II. Danckwert’s model/Penetration or surface
renewal Theory :-
6

7. III. Interfacial barrier model/Double barrier or Limited solvation
theory :-
According to the interfacial barrier model, an intermediate
concentration can exist at the interface as a result of solvation
mechanism and is function of solubility. When considering
dissolution of crystal, each face of the crystal will have the
different interfacial barrier.
The concept of this theory is explained by following equation-
G = Ki (Cs - Cb)
Where,
G = dissolution rate per unit area,
Ki = effective interfacial transport constant.
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8. Dissolution of solids
In the dissolution of solids, we have
1.Powders
2.Tablets
3.Capsules
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9. Dissolution of Powders
Wettability and Dissolution Rate of Powders
The first step in the process of dissolution is wetting of the dissolving surface,
which is in contact with the dissolution medium.
The condition for complete wetting of a solid surface is that the contact angle
should be Zero.
This condition is fulfilled only when the forces of attraction between the
liquid and solid are equal to or greater than those between liquid and liquid.
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10. Dissolution of Capsules
Dissolution of
Drug in capsule Drug in capsule mass
Capsule shell
Drug particle in Suspension
Drug in solution
Name of the APPARATUS
dosage
Capsule II (Paddle)
Drug in blood
Capsule I (Basket)
Capsule II (Paddle)
(Extended
Release) 10

11. Dissolution of tablet
Tablet Disintegration Granules Deaggregation drug
particles in suspension
Non - Disintegration
Drug in the solution in GI
fluid
Drug in blood
Name of the APPARATUS
dosage
Tablet II (Paddle)
Tablet I (Basket)
11

12. Dissolution of Sustained Release formulation
The dissolution of sustained or controlled release formulation is done by in vivo
in vitro methods. The USP dissolution testing apparatus are used for in vitro
testing of sustained action formulation , which includes
the rotating bottle
Stationary basket/ rotating filter
Sartious absortion and solubility simulator
Colum-type Flow through assembly
The time of testing may vary from 6 to 12 hours, depending upon specification
of dosage form
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13. Dissolution of suspension
The dissolution of suspension is similar to the post disintegrated form of
tablet and capsule.
Several studies have shown that the absorption of several poorly soluble
drug administered in suspension formulation is dissolution rate limited.
The apparatus used in dissolution studies are as follows
USP apparatus II (Paddle)
Rotation speed is between 25 to 100 RPM
Rotating Filter apparatus
Developed by Shah with the Basket removed
temp 37°+- 2°c
RPM 25 to 100
Dissolution medium 900- 1000 ml
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14. Dissolution of suppositories
The in vitro Dissolution testing for suppositories has always pose a
difficult problem. Early testing was carried out by simple placement in a
beaker containing medium.
Dissolution apparatus which are used for dissolution study of
suppositories
1. Apparatus I (Paddle apparatus with disk)
2. Apparatus II (Basket apparatus)
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15. Acceptance criteria
Acceptance criteria as per Indian Pharmacopoeia for various dosage form
 Conventional-release dosage forms
Level Number Acceptance criteria
tested
S1 6 Each unit is not less than D* + 5 percent**.
S2 6 Average of 12 units (S1 +S2) is equal to or greater than
D, and no unit is less than D –15 per cent**.
S3 12 Average of 24 units (S1+S2+S3)is equal to or greater
than D, not More than 2 units are less than D – 15 per
cent** and no unit is less than D – 25 per cent**.
*D is the amount of dissolved active ingredient specified in the
individual Monograph, expressed as a percentage of the labelled
content.
**Percentages of the labelled content. 15

16. Prolonged-release dosage forms
Level Number Acceptance criteria
tested
L1 6 No individual value lies outside each of the
stated ranges and no individual value is less than
the stated amount at the final test time.
L2 6 The average value of the 12 units (L1 + L2) lies
within each of the stated ranges and is not less
than the stated amount at the final test time; none
is more than 10 per cent of labelled content
outside each of the stated ranges; and none is
more than 10 per cent of labelled amount below
the stated amount at the final test time.
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17. L3 12 The average value of the 24 units (L1 + L2 + L3)
lies within each of the stated ranges, and is not
less than the stated amount at the final test time;
not more than 2 of the 24 units are more than 10
per cent of labelled content outside each of the
stated ranges; not more than 2 of the 24 units are
more than 10 per cent of labelled content below
the stated amount at the final test time; and none
of the units is more than 20 per cent of labelled
content outside each of the stated ranges or more
than 20 per cent of labelled content below the
stated amount at the final test time
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18. Acceptance criteria as per USP
Stage Number tested Acceptance criteria
S1 6 Each unit is not less than Q +5%
S2 6 Average of 12 units (S1+S2) is equal to or greater than
Q, and no unit is ;ess than Q – 15%
S3 12 Average of 24 units (S1+S2+S3) is equal to or greater
than Q, not more than 2units are less than Q- 15%, and
no units are less than Q-25%
Q is the amount of dissolved active ingredient specified in
the individual Monograph, expressed as a percentage
of the labelled content.
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19. REFERENCE
•IP 2007
•USP 2005
•Industrial pharmacy BY Lacchmann
Liebermann
•Umesh v. banakar ,pharmaceutical
dissolution testing, volume 47,marcel
dekkar, inc., new york,410-450.
•Brahmankar D.M., Jaiswal,
Biopharmaceutics and pharmacokinetics,
1997, Vallabh prakashan, Delhi,290-292.
•www.dissolutiontech.com
•www.usp.org
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