The document discusses the effect of various parameters on drug dissolution. It describes how agitation, pH, viscosity, temperature and other properties of the dissolution medium influence the dissolution rate. The amount of dissolution medium and maintenance of sink conditions are also important. Various dissolution models like Hixson-Crowell are presented.

1. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 1
A seminar as part of curricular requirement for
M.Pharm I semester
Presented by
J. Lokdep Reddy
[Reg.no.20L81S0305]
Under the guidance of
Dr.CH. Pavan kumar M.Pharm, Ph.D.
Associate professor and head
Department of pharmaceutics
Dissolution parameters

2. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 2
• Study of effect of dissolution parameters
• References
CONTENTS

3. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 3
• 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.
Dissolution parameters:
a) Effect of agitation
b) Effect of dissolution fluid
c) Influence of PH of dissolution fluid
d) Effect of surface tension of the dissolution
medium
e) Effect of viscosity of the dissolution
medium
Dissolution parameters

4. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 4
F) Effect of the presence of un reactive and reactive
additives in the dissolution medium
G) Volume of dissolution medium and sink conditions
H) Deareation of the dissolution medium
I) Effect of temperature of the dissolution medium

5. RIPER
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NAAC &
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Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 5
Effect of viscosity of the dissolution medium :
• If the interaction at the interfaces, occurs much faster than the rate of
transport, such as in the case of diffusion controlled dissolution
process, it would be expected that the dissolution rate decreases with
an increase in viscosity.
• The rate of dissolution of zinc in HCL solution containing sucrose
was inversely proportional to the viscosity of solution.
• The stoks Einstein equation express the diffusion coefficient as a
function of viscosity, can be seen from the following formula
D=UKT U = Mobility K= Boltzmann constant

6. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 6
Effect of the presence of unreactive and reactive additives in the
dissolution medium:
• When neutral ionic compounds, such as sodium chloride and sodium
sulphate, or non ionic compounds, such as dextrose, were added to
the dissolution medium, the dissolution of benzoic acid was
dependent linearly upon its solubility in the particular solvent.
• When certain buffer or bases were added to the aqueous solvent, an
increase in the dissolution rate was observed.

7. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 7
Volume of dissolution medium and sink conditions:
• The proper volume of dissolution medium depend mainly on the
solubility of the drug in the selected fluid.
• If the drug is poorly soluble in water, a relatively large amount of fluid
should be used if complete dissolution is to be expected.
• In order to maintain the effect of the concentration gradient and
maintain sink conditions, the concentration of the drug should not
exceed 10-15% of its maximum solubility in the dissolution medium
selected.

8. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721
Deaeration of the dissolution medium:
• Presence of dissolved air or other gases in the dissolution medium
may influence the dissolved rate of certain formulations and lead to
variable and unreliable results.
• Example: the dissolved air in distilled water could significantly lower
its PH and consequently effect the dissolution rate of drugs that are
sensitive of PH changes, eg., weak acids.
• Another serious effect is the tendency of the dissolved air to be
released from the medium in the form of tiny air bubbles that
circulates at random and invariably affect the of the hydrodynamic
flow pattern generated by the stirring mechanism.

9. RIPER
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NAAC &
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Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 9
• The gathering of air bubbles on the solid surface could also leads to a
reduction in the specific gravity to the point where the tablet ,or its
disintegrating powder bed, float to the top of the basket in the liquid
medium with a minimum chance of being wetted efficiently.

10. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
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Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721
Effect of temperature of the dissolution medium:
• Drug solubility in temperature dependent, therefore careful
temperature control during the dissolution process is extremely
important.
• Generally a temperature of 37 degree +_ 0.5 is maintained during
dissolution determination of oral dosage forms and suppositories .
• For topical preparations as low as 30 degree and 25 degree have been
used.

11. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 11
• The effect of temperature variations of the dissolution medium
depends on the temperature/solubility curves of the drug and
excipients in the formulation.
• Carstetensen pointed out that for a diffusion coefficient D is
dependent up on the temperature according to equation D=UKT
• U=mobility(defined as the velocity when exposed to a force of one
dyne)
• K=Boltzmann constant
• T=absolute temperature

12. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 12
• Hixson and crowell described this
w0 1/3-w1/3 =kt
where w0 is the initial amount of drug
wt is the remaining amount of drug at time t.
• plot: Data is to be plotted as cube root of drug percentage remaining
in matrix versus time.
• Application: This expression applies to pharmaceutical dosage form
such as tablets,where the dissolution occurs in planes that are parallel
to the drug surface if the tablet dimensions diminish proportionally in
such a manner that the initial geometrical form keeps constant all the
time.
Hixson-crowells cube root law

13. RIPER
AUTONOMOUS
NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 13
• Theory and practice of industrial pharmacy by Lachmann and
Libermann.
• Dissolution, bioavaibility and bioequivalence by hamed M.Abdou.
• Biopharmaceutics and pharmacokinetics by D.M bhramankar and
sunil b.jaiswal.
REFERENCES:

14. RIPER
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NAAC &
NBA (UG)
SIRO- DSIR
Raghavendra Institute of Pharmaceutical Education and Research - Autonomous
K.R.Palli Cross, Chiyyedu, Anantapuramu, A. P- 515721 14