APresentation

On

Dissolution study of solids and suspension

ByMr. Ghodake Chaitanya A.

Under the Supervision ofMr. N. A. GuajrathiAssistant Professor

P.S.G.V.P.M’s

DEPARMENT OF PHARMACEUTICSSHAHADA, DISTRICT- NANDURBAR

MAHARASHTRA.2011-2012

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

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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.

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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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I. Diffusion layer model/Film Theory :-

5Noyes whitney equation dc/dt = k (Cs- Cb)

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

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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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Dissolution of solids

In the dissolution of solids, we have

1.Powders

2.Tablets

3.Capsules

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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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Dissolution of Capsules

Drug in capsule massDrug in capsule

Drug particle in Suspension

Drug in solution

Drug in blood

Dissolution of Capsule shell

Name of the dosage

 APPARATUS

Capsule  II (Paddle) 

Capsule  I (Basket) 

Capsule (Extended Release) 

II (Paddle) 

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Dissolution of tablet

Tablet Disintegration Granules

Non - Disintegration

Drug in the solution in GI fluid

Drug in blood

Deaggregation drug particles in suspension

Name of the dosage

 APPARATUS

Tablet  II (Paddle) 

Tablet I (Basket) 

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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 filterSartious absortion and solubility simulatorColum-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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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 followsUSP apparatus II (Paddle)

Rotation speed is between 25 to 100 RPMRotating Filter apparatus

Developed by Shah with the Basket removed temp 37°+- 2°cRPM 25 to 100 Dissolution medium 900- 1000 ml

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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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Acceptance criteriaAcceptance criteria as per Indian Pharmacopoeia for various dosage form

Conventional-release dosage forms

Level Number

tested

Acceptance criteria

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.

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Prolonged-release dosage forms

Level Number

tested

Acceptance criteria

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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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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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.

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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