This document discusses dissolution testing apparatus and validation. It begins with an introduction to dissolution testing, its importance, and factors that affect dissolution. It then describes the various USP apparatus for dissolution testing and theories of dissolution. The remainder of the document outlines the validation process, including qualification phases, protocols, and maintenance. Validation establishes evidence that a process will consistently produce quality products meeting specifications.

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“ Dissolution Test Apparatus”
Presented By
Sagar Kishor savale
(M.pharm Student)
[Department of Pharmaceutics, North Maharashtra University, college of R.C.Patel Institute
of Pharmaceutical Education and Research, Shirpur, Dist.Dhule, Maharashtra.]
Email: avengersagar16@gmail.com

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INTRODUCTION
The dissolution process started to develop about 100 years ago as a field of
pharmacy and since then important progress has been made.
Interest in drug related dissolution has grown only since the
realization that dissolution is an important factor of drug
bioavailability in the 1950s. Dissolution test is required to study the
drug release from the dosage form and it’s in vivo performance.
Dissolution test is used to assess the lot to lot quality of
drug product. The development and validation of dissolution
procedures isofparamountimportance during development of
new formulation and in quality control.The objective of this project is
to review the Validation Of the Dissolution Apparatus.
Defination - Dissolution is a technique in which a solid substance
solubilizes in a given solvent i.e. mass transfer from the solid surface
to the liquid phase (Brahmankar et al., 1995).
Dissolution examination is a process which is used to measure the
release profile of the drugs from formulations which are commonly
solid oral dosage forms like tablets and capsules.
Dissolution mainly takes place in two steps, 1) Liberation of the drug
from the formulation,2) Dissolution of drug in the liquid medium.
(GowthamarajanK., et al., 2010).Dissolution testing of formulations
was brought out in 1960s and it was recognized through
healthregulatory authorities in 1970s, and then the importance of
dissolution has grown rapidly. Modern researches lead to the
development of in-vitro dissolution tests as an alternate of animal
bioequivalent studies (Rolf Rolli et al., 2003). The dissolution process
needs apparatus, dissolution medium, and test conditions that
provide a method i.e. selective yet sufficiently rugged and
reproducible for every day operation andcapable of being

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transferred between research laboratories. The basic destination of
dissolution testing is to allow the measurement of bioavailability of a
dose in addition to bioequivalence of batch to batch. Hence properly
organized dissolution test is necessary for biopharmaceutical
formulations. The principle for carrying these tests is that, for a
product to be therapeutically efficient, the drug must be discharged
from the product and should broadly be dissolved in the fluids of the
gastrointestinal tract. The API in solution form helps the absorption
of the drug from the gastrointestinal tract into the systemic
circulation to achieve its desired target area to exert its effect. The
data received as a result of dissolution examination guides the
development of novel formulation and product development and
also dissolution isnecessary for regulatory approval for product
marketing. (SaeedA.Qureshi, et al) In these times all solid oral dosage
forms need dissolution testing as a quality control test before
brought in into market.
Dissolution is expressed in terms of a rate process. If the rate
increases, the dissolution process also increases. Dissolution rate
possibly defined as the amount of drug substance that enters
solution per unit time below standardized experimental condition.
Noyes-Whitney’s equation is valuable in estimation of rate of
dissolution (SubrahmanyamC.V.S, et al., 2008).
The rate of dissolution is described as:
dc / dt =KS (CS- C)
… Eq. no. 1
Where K = dissolution rate constant,
S = surface area of the particles,

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CS= equilibrium solubility of drugs,
C = concentration of drug in the bulk of drug.
Physical and Chemical Properties of Drugs
The initiative in the development of a fresh dissolution is the
evaluation of physical and chemical information of drug content.
Knowledge ofthese information will help the selection of dissolution
medium and its volume. Some of the physicochemical properties of
API that determine the dissolution characteristics are:
•Ionization constants (pKa),
•Solubility as a function of pH,
•Solution stability as a function of pH,
•Particle size,
•Crystal form, and
•Common ion, ionic strength, and buffer effects,
•Temperature
•Agitation

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NEED OF DISSOLUTION TESTINGS
Fig 1: Need of dissolution testing
THEORIES OF DISSOLUTION
Several theories have been proposed to explain the process of
dissolution. Some of the important ones are -
A) Diffusion model/film theory
B) Danckwert’s model/ surface renewal theory
C) Interfacial barrier model/limited solvation theory

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A)DIFFUSION LAYER MODEL
Theory states that dissolution process consists of two consecutive
steps-
-Solution of solid to form a thin layer at the solid liquid
interface called stagnant layer

 -Diffusion of soluble solute from the stagnant layer to the
bulk of solution .
The second step is comparatively slower hence the rate limiting
steps-
Equation:- dc/dt= k(Cs-Cb)
…Eq No. 2
Applying fick’s second law of absorption the equation can be
modified as following.
dc/dt = DAkw/o(Cs-Cb)/Vh…Eq No. 3
where,
dc/dt = rate of dissolution
D = diffusion constant
A = surface area exposed , k = partition co efficient
Cs = concentration of drug in stagnant layer
Cb = concentration of drug in bulk of solution.
V = volume of dissolution medium ,
h = thickness of layer

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Noyes-Whitney equation assumes that the surface area of solid
remain constant which is practically not possible to account for the
surface area change Hixon-Crowell cubic root law is used
Wo
1/3
-W
1/3
= Kt
…Eq. No. 4
Where, Wo = initial mass
W = mass after time t
K = dissolution rate constant
B) DANCKWERT’S MODEL
The model assumes no stagnant layer on solid liquid interface.
Instead suggest turbulence in dissolution medium and as a result of
turbulence agitated fluid consisting of macroscopic mass of eddies or
packets reach the interface in a random fashion due to eddy current
as a result absorbs solute and carry it to the bulk of solution.
Equation ,Vdc/dt = dm/dt = A(Cs-Cb)(Dγ)
1/2
…Eq. No.5
Where ,V = volume of dissolution medium
dc/dt = rate of diisolution medium
dm/dt = rate of change in mass
A = surface area,
γ = surface tension of dissolution medium

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C) INTERFICIAL BARRIER MODEL
Above mentioned both theory assumes,
-The rate determining step that control dissolution is mass transfer
-Solid solution equilibrium is achieved at solid liquid
Interface
According to this theory an immediate concentration existatinterface
as a result of solvation mechanism and is function of solubility rather
than diffusion
Such concept can be given by
G = Ki(Cs-Cb)eqn….(6)
where, G = dissolution rate/ unit area ,
Ki = effective interface transport constant
FACTORS AFFECTING DISSOLUTION
Following factors to be considered in dissolution testing of drug are
1) Factors related to drug substance.
a) Particle size
b) Polymorphism
c) Hydrates and solvates
d) Surface area
2) Formulation factors
a) Effects of diluents and disintegrants
b) Effects of binder and granulating agents
c) Effects of lubricants
d) Effect of processing factors.
3) Medium used for dissolution testing
a) Volume
b) Shape of dissolution vessels

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c) Co-solvents added /enzymes, surfactants
4) Temperature of medium
5) Dissolution apparatus
6) Hydrodynamics of dissolution
a) agitation rate
b) shape of dissolution vessel
c) placement of dosage form in vessel
d) sinkers for floating products
FACTORS RELATED TO DRUG SUBSTANCE
a) Particle size
 Particle size and surface area are inversely
proportional to each other in affecting dissolution.
Higher dissolution rate may be achieved by reducing
particle size and hence increasing surface area.
b) Polymorphism
Drug
Amporphous Ploymorphic
Enantiotriphic Monotrophic

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Dissolution Apparatus-
Fig 2: Rotating Basket (USP apparatus 1)
USP APPARATUS 1
Rotating Basket
• Standard 40-mesh basket.
• Other mesh size baskets are
available.
• Volume ranges from 100 mL
to 4L.
• A variety of vessel sizes are
available.

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Fig 3: Paddle apparatus (USP apparatus 2)
USP APPARATUS 2
Paddle
• Standard stainless
steel paddle or Teflon-
coated
stainless steel paddle.
• Special Teflon and
PEEK paddles are
available.
• Volume ranges from
100 mL to 4L.
• A variety of vessel
sizes are available.

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Fig 4: Reciprocating cylinder (USP apparatus 3)
USP APPARATUS 3
Reciprocating Cylinder
• Sequential operation
for pH profiling.
• Volume ranges from
100 mL to 1L.
• 300 mL outer tubes are
standard

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USP APPARATUS 4
Flow throught the cell
 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
per min.
 It must deliver a constant flow(±5%
of the nominal flow rate);the flow
profile is sinusoidal with a pulsation
of 120 ± 10 pulses per m
Fig 5: Flow through the cell (USP apparatus 4)

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USP APPARATUS 5
Paddle over Disk
• Standard stainless steel with
disposable stainless screens.
• Used for transdermal patches
in a standard round bottom
vessel.
• Volume 900 mL.
Fig 6: Paddle over disk (USP apparatus 5)

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Fig 7: Rotating cylinder (USP apparatus 6)
USP APPARATUS 6
Rotating Cylinder
• Two-piece assembly for
testing transdermal patches
using Apparatus 1 and 2
dissolution testers.
• Volume 900 mL.

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USP APPARATUS 7
Reciprocating Holder
•Utilizes sequential
operationand a variety of
dosage holders.
• Volume ranges from 20 mL
to275 mL.
• Useful for transdermal
patches,osmotic pump
delivery systemsas well as
other non-disintegrating
dosage forms.
Fig 8: Reciprocating holder (USP apparatus 7)

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VALIDATION
WHAT IS VALIDATION?
Establishing documented evidence which provides a high degree
ofassurance that a specific process will consistently produce a
product meeting its pre-determined specifications and quality
attributes`
MORE WAYS TO DESCRIBE VALIDATION…
• A state of being, which if unchanged, assures that a pharmaceutical
manufacturing system will consistently produce quality medicines.
• Part of the lifecycle of pharmaceutical manufacturing systems
starting withthe conceptual elements of process design and ending
with the cessationof production.
•A sequence of complementary activities that include verifications,
tests, and documentation.
• An extension of Good Engineering Practices that includes review
and approval by an independent quality organization.
• A mindset that assures that systems are designed, constructed, and
can be robustly operated to produce quality medicines
WHY IS VALIDATION DONE?
We validate the production process because, in part, the process
definesthe product and assures its quality attributes.

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SIDEBAR: WHAT IS THE PRODUCT?
What are the “pre-determined specifications andquality attributes”?
• Safety
• Efficacy
• Identity
• Potency
• Purity
Definition of Validation
“documented
evidence”
If it’s not documented it’s just a rumor
“high degree
of
assurance’’
The risks to product quality have been assessed, the
process has been tested, and the remaining risk has
been found to be acceptable
“specific
process”
Systeminclusions and exclusions are well defined
(hardware, software, procedures, environment).
Critical Attributes are clear and measureable.
“consistently
produce”
Documented evidence of repeatability

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“pre-
determined
specifications
and
quality
attributes”
“In the beginning there was a URS…and on the 6th
day there were test protocols”
EQUIPMENT VALIDATION
 A validation programme involves various components
inpharmaceutical organisation related to process,
equipment and product.
 It is a regulatory requirement for pharmaceutical companies
toperform Instrument Validation on all new instruments.
 Instrument Validation requires detailed knowledge of
theinstrumentation system being validated and is therefore
usuallyperformed by the company supplying the instrument.
Definition (US-FDA):- Validation is the establishment of
documentary evidence which provide a high degreeassurance of
specified processwill consistently produce the product meeting with
predetermined specification and quality attributes.
Validation studies are performed for analytical equipment, tests,
facility systems such as air, water, steam, the manufacturing,
cleaning, sterilization processes

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CYCLE OF VALIDATION
Fig 8: Cycle of validation
VALIDATION STUDY PHASES
Phase 1:
Pre-Validation Phase (Qualification Phase)
Phase 2:
Process Validation Phase (Process Qualification phase)
Phase 3:
Validation Maintenance Phase

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VALIDATION PLAN
Fig 8: Validation plan
PHASE-1(QUALIFICATION)
DESIGN QUALIFICATION:
“A documented review of the design, at an appropriate stageor
stages in the project, for conformance to operational and
regulatory expectations.”
Specification of requirements for facilities, plants andequipment,
mainly in connection with purchase/modificationof equipment.

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DQ REVIEW DOCUMENTS
User Requirement Specification (URS)
Functional Specification (FS)
Tender Specifications and Drawings
Vendor Quality procedures and documents
Purchase Specification
INSTALLATION QUALIFICATION
IQ verifies that the equipment has been installed in accordance
with the manufacturer’s recommendation in a proper manner and
that all of the devices are placed in an environment suitable for
their intended purpose.
COMPUTER AND SOFTWARE IQ
SoftwareRequirements and Specifications should be clear, written
down, and approved by the appropriate personnel prior to creating
the software package.
Software Installation should be recorded, when made, so that
theproper model numbers, serial numbers, installationdateetc.
PHASE2 (Process qualification phase)
OPERATIONAL QUALIFICATION
The documented action of demonstrating that processequipment
and ancillary systems work correctly and operateconsistently in
accordance with established specifications.

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Operation Qualification (OQ) for testing the equipments in
theselected user environment is to ensure that it meets the
previouslydefined functional and performance specifications.
How may runs are to be performed during Operational
Qualification (OQ) testing?
Guidelines stress the importance of equipment qualification
simulating actual production conditions, including 'worst case'
situations and that "tests and challenges should be repeated a
sufficient number of times to assure reliable and meaningfulresults.
Three consecutive batchesare recommended for process validation
rather than for equipment qualification. No specific number of "runs"
for equipment qualification, but multiple tests to simulate actual
operating ranges and to establish consistency are expected.
PERFOMANCE QUALIFICATION
Assurance that the process continues to comply with established
requirements. Performance Qualification (PQ) for testing that
thesystem consistently performs as intended for the selected
application.
Purpose- To define testing requirements in a
product/process/performance/qualification/validation protocol.
Principle- Performance qualification validation testing plan are
usually process or product specific but will include the following
background and result for the plan, testing method used, and a
predetermined and general and/or specific acceptance criteria.

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RE-VALIDATION
Re-validation is required when the operating equipment or system
has been changed in some way.
It is carried out when:
Major mechanical equipment has been replaced
Computer systems have been replaced
New products have to be run on the system.
Critical items have been replaced or repaired.
RETRO-VALIDATIONS
Retrospective validation must be done on equipment that records
have either been lost or validation was not provided for in the initial
life of the machine. Retrospective validations get more difficult the
older the machine.
PHASE-3 (VALIDATION MAINTENANCE PHASE)
It is the maintenance of the validation which has been
alreadyestablished.

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MASTER VALIDATION PROTOCOL
The Master Validation Protocol (MVP) is the outline of the validation
for a facility.
MVP:
Identifies which items are subjects to validation. Defines the nature
and extent of testing expected to be done on each item.Outlines the
test procedures and protocols to be followed to accomplish
validation.
Describes functional responsibilities and requirements to document
the work carried out and the results obtained.
INSTALLATION QUALIFICATION
Installation qualification consists of documented verification that all
key aspects of the dissolution apparatus are in working condition and
have been properly installed in accordance with manufacturer’s
specifications in the proper operating environment.
CALIBRATION
The installation qualification should document that specific devices
contained within the dissolution apparatus (e.g., speed, time, and
temperature displays) have been calibrated to traceable standards.
INSTALLATION QUALIFICATION-
Environmental Conditions
Computerized System
Equipment Information

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Preventive maintenance
SOP
Utilities
DISSOLUTION APPARATUS VALIDATION
 Dissolution is defined as the process by which a known amount of
drug substance goes into solution per unit of time under
standardized conditions.
 The primary goal of dissolution testing is to be used as a qualitative
tool to provide measurements of the bioavailability of a drug as well
as to demonstrate bioequivalence from batch-to-batch.
 Validation is achieved by performing a series of validation activities;
for a dissolution apparatus, validation is obtained through
installation qualification and operational qualification.
APPARATUS 1
Vessel: cylindrical, 160-210 mm height, inside diameter 98-106 mm,
nominal capacity is 1000 mL; sides are flanged at the top. Shaft:
positioned so that its axis is not more than 2 mm at any point from
the vertical axis of the vessel and rotates smoothly and without
significant wobble.
Materials of Construction: Shaft and basket components are
stainless steel, type 316 or equivalent. Basket position: the distance
between the inside bottom of the vessel and the basket is
maintained at 25 +/- 2 mm during the test.
APPARATUS 2
Vessel: cylindrical, 160-210 mm height, inside diameter 98-106 mm,
nominal capacity is 1000 mL; sides are flanged at the top. Shaft:
positioned so that its axis is not more than 2 mm at any point from

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the vertical axis of the vessel and rotates smoothly and without
significant wobble.
MATERIALS OF CONSTRUCTION: Shaft and blade are a single
entity that may be coated with a suitable inert coating.
Blade position:The distance between the inside bottom of the vessel
and the blade is maintained at 25 +/- 2 mm during the test. The
blade passes through the diameter of the shaft so that the bottom of
the blade is flush with the bottom of the shaft
OPERATIONAL QUALIFICATION
Operational Qualification consists of documented evidence that the
equipment operates as intended and is capable of consistent
operation within established specifications.
The operational qualification of a dissolution apparatus should
include the following verifications:
TEMPRATURE DISTRIBUTION STUDY
A temperature distribution study should be conducted during the
operational qualification. The study should include temperature
mapping of each vessel contained within the dissolution apparatus.
Temperature should be mapped using a data system for a minimum
time that is based on the monograph or 1 hour, whichever is greater.
The temperature must remain at 37°C ± 0.5°C;
ROTATIONAL SPEED STUDY
A rotation speed study should be conducted during the operational
qualification. The study should include a measurement of the speed
of the shaft rotation for each vessel contained within the dissolution
apparatus.

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SYSTEM SUITABILITY
A system suitability test using USP calibrators should be conducted
during operational qualification testing. The procedure fordissolution
and sampling is outlined in the Certificates supplied with each USP
Calibrator tablet for each apparatus. The calibrators used for the test
are disintegrating tablets (Prednisone) and non-disintegrating tablets
(Salicylic Acid). The test is successful if the percent of drug released
at 30 minutes falls within a pre-established range.
The ranges for each combination of apparatus and calibrators at 50
or 100 RPM are established by the USP and are different for each lot
of calibrators.
PERFORMANCE QUALIFICATION
In Performance qualification different types of dosage form are used.
CONCLUSION
 Validation provides the good quality product and the
equipment.
 Validation gives the surety that equipment having the good
qualification like design, operation, installation, and
performance qualification which have pre-determined.
 Validation data should be generated for the all types of the
product and the equipment to demonstrate the adequacy of
the manufacturing process.

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REFERENCES
1. PotdarManohar A. “Pharmaceutical quality assurance” 2ndEdition,
NiraliPrakashan, p-8.1-8.7
2. Nash Robert A. “Pharmaceutical Process Validation”3rd Edition,
Marcel Dekker Inc, p-442
3. Cole Graham C. ‘Pharmaceutical Production Facilities” 2nd Edition,
CRC Press, p-199
4. Despautz Joseph F. “Automation And Validation Of Information In
Pharmaceutical Processing” Vol-90, Marcel Dekker Inc, p-221
5. Berry And Harpaz“ Validation Of Active Pharmaceutical
Ingredient”2nd Edition, CRC Press, p-429
6. Sharon M.Averell Frost, “ Introduction to the Validation of a
Dissolution Apparatus.”p-19.
7.http://www.pharmainfo.net/
(equipment-validation-articles)
(laboratory-equipment-qualification)
8. Encyclopedia of pharmaceutical technology; James swarbrick,
James C. Boylan; 2nd edition; volume-I,p-718-724
9. Pharmaceutical dissolution testing,BanakarUmesh V;volume-49,p-
94-96,p-174-179
10. Biopharmaceutics and pharmacokinetics; D.M.Brahmankar, Sunil
B. Jaiswal; vallabh prakashan,p-20-25
11. USP asian edition,2005,p-2303-2310
12. European pharmacopoeia-1997,p-128-132
13. www.dissolutiontech.com
(Need of dissolution testing)
14. The Theory and Practice of Industrial Pharmacy, Leon Lachman,
Herbert A. Lieberman, Joseph L. Kanig, 3rdedition, Varghese
Publishing House, p-303
15. Text Book of Physical Pharmaceutics, C.V.S.Subrahmanyam,p-97