These documents discuss stability testing of pharmaceutical products. Stability testing aims to assess the quality of drug products over time under various environmental conditions and helps determine shelf life. It seeks to ensure drug products remain safe and effective and within approved specifications. Degradation can occur through physical changes like loss of volatile components or water, or chemical changes such as hydrolysis, oxidation, or isomerization. Proper packaging and storage conditions can help prevent degradation and extend a drug's shelf life.

3. These studies provide information about the packaging in that it
is not reactive, additive, or absorptive so that the identity,
strength, quality and purity of the drug product is not affected,
also to provide clearance on stability process flow.
To assessment of the stability characteristics of all
drug products manufactured / packaged and/or
repacked by Pharmaceuticals companies.
To establish and extend the shelf life for products

4. STABILITY
 Stability of a pharmaceutical product may be
defined as the capability of a particular
formulation in a specific container/closure
system to remain within its
 Physical
 Chemical
 Microbiological
 Therapeutic
 Toxicological Specifications

5.  There are various mechanisms by which drug
products may degrade & lead to
 Loss of active
 Increase in concentration of active
 Alteration in bioavailability
 Loss of content uniformity
 Decline of microbiological status
 Loss of content uniformity
 Decline of microbiological status

6.  Loss of pharmaceutical elegance and patient acceptability
 Formation of toxic degradation products
 Loss of package integrity
 Reduction of label quality
 Modification of any factor of functional relevance.
REASONS FOR STABILITY TESTING
 Our concerns for patients welfare
 To protect the reputation of the producer
 Requirements of regulatory agencies
 To provide a database that may be of value in the formation of
other products

7. What is kinetics?
 Kinetics is a rate of reaction which takes place in a particular compound.
 It may be change in parent compound either physical or chemical.
 Physical change includes biotransformation.
 Chemical change include degradation
Application of kinetics in stability:
 To understand the mechanism of what kind of change.
 To estimate the degradation time.
 Some time half life or shelf life may be determined by the kinetic.
 For prediction of process mean by keeping the compound, what kind of change
and how much time will be taken for that change will be estimated.

10.  The incapacity or incapability of a
particular formulation in a specific
container to remain within a particular
chemical, microbiological, therapeutical,
physical & toxicological specification.

11. Pharmaceutical degradation is of following
type.
It can be divided into three major types:
1. Physical degradation
2. Chemical degradation
3. Microbiological degradation

12.  It is the degradation which results into the
change of physical nature of drug.
The formulation is totally changed by way of
appearance, organoleptic properties, hardness,
brittleness, particle size.

13.  Factors effecting physical
degradation are as under:
1. Loss of volatile components
2. Loss of H2O
3. Absorption of H2O
4. Crystal growth
5. Polymorphic changes
6. Colour changes

14. 1) Loss Of Volatile Components:
Many drugs and excipients may be lost from
pharmaceutical products at ambient
temperature through vaporization. These
Volatile components such as
Alcohol ,ether,Iodine, volatile oils,Camphor
menthol etc escape from the formulations
rendering them degraded.

15.  EXAMPLE:
Aromatic waters
Elixirs
Some types of tablets which contain
aromatic water (Nitroglycerine tablets)
PREVENTION:
Such product should be placed in well
closed container
Temperature should be proper.

16. 2) LOSS OF H20:
 Evaporation of water from liquid preparations
will cause concentration of the drug to change
with the possibility of crystilization occurring if
the solubility of the drug in the solvent is
exceeded. Water loss from oil- in – water
creams may result in a decrease in volume
and a surface rubbery feel. Further
evaporation of the water will cause the
emulsion to crack.

17.  Some drugs are efflorescent, which mean
they will lose water to the atmosphere
resulting in a concentration of the drug and
overall weight loss.
 Water loss to the atmosphere can be
prevented by storing the pharmaceutical
product in a well closed container.

18.  Saturated solution: by loss of water they become
supersaturated and precipitate as crystals are
formed .
 Emulsions: Loss of water lead to separation of the
two phases and change to other type
 Creams: especially oil/water, they become dry by
loss of water

19. Hygroscopic drugs absorb the water from external
atmosphere causing the physical degradation.
For example, some drugs are delisquent (calcium
chloride and potassium citrate), whereas others are
hygroscopic (glycerol and dry plant extracts).
Effervescent powders and tablets will deteriorate if
stored in a moist atmosphere..

20.  Powders: Liquification and degradation may occur as a
result of absorption of water
Suppositories which base made from hydrophilic
substances as Glycerin, Gelatin, polyethylene glycol.
The consistency of these forms becomes jelly-like
appearance.
Products should be placed in well-closed container and
in dry place.

21.  Polymorphs are different crystal forms of the
same compound .Polymorphs differs from one
another in the crystal energies, the more
energetic ones converting to the least energetic
or most stable one to least stable one. Different
polymorphs of the same drug may exhibit
different solubility and melting points.

22.  In polymorphic changes crystal forms are
changed. A stable crystal form loosens.
This may cause alteration in solubility and
possibly crystalline growth in aqueous
suspensions.
 Ex Chloremphenicol Palmitate
 Cocoa Butter

23.  Drugs when loose water,become saturated and
crystal growth occurs.Molecules in the crystal
are not static, they can grow in size and move
when there is a medium to travel.
 Crystallization is enhanced in porous tablets.

24.  Carbamazepine tablets containing
stearic acid form column shaped
crystals on tablet surface during
storage at high temperature.

25. Colour changes are of two types.
Loss of colour
Development of colour
1) Loss of colour is due to
· PH change
2) Development of colour is due to
· Exposure to light

26.  EXAMPLE:
 Phenolphthalein color changes as the Ph changes.It is
colorless in acidic solution and pink in basic.
 PREVENTION:
PH should be adjusted
Exposure to light should be avoided
An attempt has been made to prevent the fading by
incorporating UV light absorbing material.

27. Formulation Likely physical
instability problems
Effects
Oral solutions 1- Loss of flavour
2- Change in taste
3- Presence of off flavours
due to interaction with
plastic bottle
4- Loss of dye
5- Precipitation
6- discoloration
Change in
smell or
feel or
taste

28. Formulation Likely physical
instability problems
Effects
Suspensions 1- settling
2- caking
3- crystal growth
1-Loss of drug
content
uniformity in
different doses
from the bottle
2- loss of
elegance.

29. Formulation Likely physical
instability problems
Effects
Emulsions 1- Creaming
2- coalescence
1- Loss of
drug content
uniformity in
different doses
from the bottle
2- loss of
elegance

30. Coalescence

31. Formulation Likely physical
instability problems
Effects
Tablets Change in:
a) Disintegration time
b) Dissolution profile
c) Hardness
d) Appearance (soft and
ugly or become
very hard)
Change in
drug release

32. Formulation Likely physical
instability problems
Effects
Capsules Change in:
a) Appearance
b) Dissolution
c) Strength
Change in
drug release

33. Formulation Likely physical
instability problems
Effects
Semisolids
(Ointments
and
suppositories)
1. Changes in:
a) Particle size
b) Consistency
2. Caking or
coalescence
3. Bleeding
1-Loss of drug
content
uniformity
2- loss of
elegance
3-change in
drug release
rate.

34. It is the separation of chemical
compound into elements or simpler
compounds. Change in the chemical
nature of the drug is called as
chemical degradation.

35.  Types of chemical degradation are
1. Hydrolysis
2. Oxidation
3. Decarboxylation
4. Isomerization
5. Polymerization

36.  Splitting by water.
 Drugs with functional groups such as esters,
amides, lactones or lactams may be susceptible
to hydrolytic degradation.
 It is probably the most commonly encountered
mode of drug degradation because of the
prevalence of such groups in medicinal agents
and the ubiquitous nature of water.

37.  Example ASPIRIN:
Aspirin degrade into salicylic acid
and acetic acid giving vinegar like
odour.

38.  Removal of an electropositive atom,
radical or electron, or the addition of
an electronegative atom or radical.
 Types:
Oxidation has two types
· Auto-oxidation
· Photo-oxidation

39. Oxidation in which the oxygen present in
the air is involved.
This process proceeds slowly under the
influence of atmospheric oxygen
e.g. Oil, fats & unsaturated compound can
undergo auto- oxidation

40. Oxidation in which removal of the electron
is involved with out presence of O2.
This type is less frequently encountered
e.g. It occurs in adrenaline, riboflavin &
ascorbic acid etc.

41. Elimination of CO2 from a compound.Drug
substances having a carboxylic acid group are
sometimes susceptible to decarboxylation,
 4-Aminosalicylic acid is a good example.

42. It is the process by which one molecule is transformed
into another molecule which has exactly the same
atoms, but the atoms are rearranged e.g. A-B-C → B-
A-C
Conversion of an active drug into a less active or
inactive isomer having same structural formula but
different stereochemical configuration

43.  Types of Isomerization:
1) Optical Isomerization
2) Geometrical Isomerization
OPTICAL ISOMERIZATION:
A change in the optical activity of a drug may result as
a change in its biological activity.
It is further divided into:
(i)RACEMIZATION
(ii) EPIMERIZATION

44. RACEMIZATION:
It involves the optically active form of a
drug into its enantiomorph.
E.X : By the action of heat (-)
hyoscyamine is readily converted to
atropine which is the racemic mixture
of (+) & (-) hyoscyamine.

45.  Epimerization:
It occur with the compound having more
than one asymetric carbon atom in the
molecule.
E.X: Under prolonged storage solution
containing ergometrine is decomposed
by hydrolysis and isomerized to
ergometrinine.

46. GEOMETRICAL ISOMERIZATION:
 Loss of activity due to the difference in potency
exhibited by CIS & TRANS isomers of some organic
compounds.
EX: Active form of VITAMIN A molecule has all trans
configuration.In aqueous solution as a component of
multivitamin preparation,in addition to oxidation
VITAMIN A PALMITATE isomerizes and form 6-mono
cis and 2,6 di-cis isomers,both have low potency.

47.  Combination of two or more identical molecules
to form a much larger and more complex
molecule.
e.g. Degradation of antiseptic formulations and
aldehydes is due to
polymerization. Formaldehyde solution may
result into formation of white deposit when
stand in cold.

48. Photodegradation is the process by which light-
sensitive drugs or excipient molecules are
chemically degraded by light, room light or
sunlight.
PHOTOLYSIS:
It is defined as decomposition of a drug by light.

49. Photodegradation of Primaquine & chloroquine give
different products by various pathways.
Sodium nitropruside stable for 1 year if protected
otherwise may degrade after 4 hours.
It can be prevented by :
Suitable packing in amber coloured bottles.
Cardboard outers
Aluminium foil over wraps.

50. Stabilization of drugs against
hydrolysis, oxidation and
photolysis:
TEMPERATURE:
All the drug products are stored at suitable
temperatures to avoid thermal acceleration of
decomposition.
LIGHT:
Light sensitive materials are stored in ambered
colour bottles

51. Humidity
Packing materials are chosen (usually glass
and plastic) to prevent exposure of drug
products to high humid condition.
Oxygen
Proper packing keeping the oxygen content of
the solution less and leaving very little head
space in the bottle above the drug products
are methods to fight against oxidation

52.  Contamination of a product may sometimes
cause a lot of damage and sometimes may not
be anything at all. Thus it is dependent on the
type of microbe and its level of toxicity it may
produce.
If parenterals or opthalmic formulations are
contaminated, it may cause serious harm.

53.  Pyrogens which are the metabolic products
of bacterial growth are usually lipo
polysaccharides and they represent a
particularly hazardous product released by
gram negative bacteria. If administered
inadvertently to a patient they may cause
chills and fever.

54.  suitably designing the containers
 usually using single dose containers
 sticking to proper storage conditions
 adding an antimicrobial substance as
preservative.

55.  THERMAL ANALYSIS:
Following methods can be used for
detection,
DIFFERENTIAL SCANNING CALORIMETRY
(DSC)
DIFFERENTIAL THERMAL ANALYSIS (DTA)
DIFFERENTIAL THERMOGRAVIMETRY
(DTG)

57. For products stored at room temperature.
For products stored at refrigerator.
for products stored at room temperature (for long term conditions at 25
°C 60 % RH).
For products stored at room temperature in climatic zone III and IV.
For products stored at room temperature in climatic zone I and II.
For products stored at refrigerator.

58. Station 1: (40
°C  2 & 75 %
RH  5).
Station 2: (30 °C
 2 & 65 % RH 
5).
Station 5: (30 °C
 2 & 35 % RH 
5).
Station 4: (2 - 8) °C.
Station 3: (25 °C
 2 & 60 % RH 
5).
Storage Conditions

59. Stability
condition
Zone
Product
storage
conditions
Station
Storage
condition
Temperature/Hu
midity
Testing
stations
(Month)
Accelerated
all
Room
temperature
1
40°C2°C / 75% 
5%RH 0, 1, 2,3
and 6
all
Refrigerator
storage
3
25°C2°C / 60%5
%RH
Long-Term
III, IV
Room
temperature
2
30°C 2°C /
65%5%RH
30°C 2°C /
35%5%RH
0, 3, 6, 9,
12, 18, 24,
36, 48 and
60
I, II
Room
temperature
3
25°C2°C / 60%5
%RH
all Refrigerator 4 (2 – 8)°C
Intermediate I, II
Room
temperature
2
30°C 2°C /
65%5%RH
0, 3, 6, 9
and 12

60.  Drug liquid preparation stored at
50,60,70,85,100 and 121 0C
 Also study performed at refrigerator temp.
 Sampling: First year- 3 month interval second
year-6 month interval
Four climatic zones:
 Temperature zone 210C/45% RH
 Mediterranean zone 250C/60% RH
 Tropical zone 300C/70% RH
 Desert zone 300C/35% RH

61.  Drug substances fade or darken on exposing to
light can be controlled by using amber glass or
opaque container.
 By exposing drug substances to 400 & 900 (FC) of
illumination for 4 & 2 weeks to light and another
sample examined protected from light.
 Results found on appearance and chemical loss
may be recorded.
 Comparing color or using diffused reflectance
spectroscopy for examination.
 E.g. cycloprofen becomes very yellow after five
days under 900 foot candles of light.

62.  Sensitivity of the drugs to atmospheric oxygen
must be evaluated from which it should be
evaluated from which it should be packed in
inert atmosphere condition with antioxidants is
decided.
 Here high oxygen tension plays important role
to investigate stability usually 40 % of oxygen
atmosphere allows for rapid evaluation.
 Results were correlated with inert & without
inert condition.

63.  Presence of moisture may cause hydrolysis
and oxidation.
 These reactions may accelerated by
exposing the drug to different relative
humidities.
 Control humidity by lab desiccators.
 Closed desiccators are placed in an oven to
provide constant temperature.

64.  It is useful when degradation is due to:
› Microbial contamination
› Photochemical reaction
› Diffusion
› Excessive agitation
 When the product losses its integrity at
high temperatures.
 When the order changes at elevated
temperature.

66. Chemical stability
Oxidation
 Cholesterol and phospholipids containing unsaturated fatty acids undergo
oxidation. One
 solution to this problem is to use phospholipids which contain saturated fatty
acids.
 The peroxidation of lipids can be minimized by use of antioxidants such as
Vitamin E
Hydrolysis
 Lecithin undergoes hydrolysis to give lyso-lecithin and other degradation
products. Therefore, it is important to start with phospholipids which are free of
lysolecithin (also of any phospholipases).
Crystallization
 The formation of ice crystals in liposomes (for example when liposomes are
partially frozen and thawed), the subsequent instability of bilayers leads to the
leakage of entraped material.
 When liposomes are subjected to a freeze thaw cycle and freeze drying in the
absence of a cryoprotectant such as lactose, they lose the entraped
compounds on reconstitution.

67. Physical stability
The physical stability of liposomes on storage can be studied by monitoring the amount of
leaked material from liposomes and by the size of liposomes. types are
• leakage
• aggregation
• coalescence
• Fusion
Aggregation
Aggregation is the formation of larger units of liposomal material; these units are
still composed of individual liposomes. In principle, this process is reversible e.g. by applying mild
shears forces, by changing the temperature or by binding metal ions that
initially induced aggregation.
Coalescence
coalescence of liposomes, which indicates that new colloidal structures are formed. As coalescence
is an irreversible process; the original liposomes cannot be retrieved.
Remedy:
An increase in physical stability of liposomes can be achieved by increasing amount of charge on
liposomes. An increase in physical stability against aggregation and fusion can be
increase by increasing surface charge density of liposomes consisting of phosphatidylcholine
and phospholidylserine.

68. Biological
Biological stability of liposomes, depends on the presence of agents such
as proteins that interact with liposomes upon application and depends
on the administration route. Strategies used to enhance biological
Stability tests for parenterals
1. Leakage test
a. Dye test: it is used for ampules. Ampule is entirely submerged in dye
solution(0.5-1%methylene blue)negative pressure will cause the dye
penetrate into the ampule. This will visible after the ampule has been
washed externally to clear whole of its dye.
b. Bubble test: air through syringe is injected into vials then these are
submerged into water. Incompletely sealed vials will eject air into water
in the form of bubbles.
2. Clarity test:
Ampules and vials are checked against black background for light
particles and against white background for dark colored particles.
3.PYROGEN TESTS:
1.invivo…..tests for rabbits
2.invitro…..LAL test

69. › Test for rabbits.
Healthy rabbits of either sex, weight not less than 1.5kg test dose is
selected acc. to their wt keep them in noise free area and temp
equal to the body temp.
Rabbits should be used once in 48hrs if they don’t show temp rise
otherwise they should be used after 2 weeks
PROCEDURE:
1. Take 3 rabbits .fasted over 24 hrs
2. Insert pyrometer in the rectum of rabbit and note temp. This will be
the initial temp.
3. Insert the test sample in the marginal ear vein of rabbit
4. Take consecutive reading of temp. After 30 min for 3 hrs.
INTERPRETATION OF RESULT:
If no individual rabbit show an individual rises in temp of 0.5 C or the
sum of 3 rabbits does not exceed than 1.4 C, the sample is passed
,but if any rabbit show an individual rise in temp of 0.5 C than test 5
other rabbits
Of not more than 3 out of 8 rabbits show individual rise in temp. of 0.5
C or the sum of 8 rabbits temp rise does not exceed 3.4 C the
material under examination meet the requirement.

70. › LAL TEST
 Basis: The lysate reagent reacts wit
endotoxin and turns the blood pf horse
shoe crab into semi solid mass. Because
amebocyte contains granules with a
clotting factor known as coagulate that is
released when it comes in contact with
endotoxin.

71. STERLITY TEST:
This test is used to check the presence of microorganism in sample
METHOD: MEMBRANE FILTRATION METHOD
1. Two types of media are used
a. Fluidthioglycolate medium(FTM)
b. Tripticase soy broth(TSB)
2. Three controls are made
a. Sample flask
b. Positive control flask
c. Negative control flask
3. Incubate them (FTM at 32C and TSB at 22C) for 14 days.
INTERPRETATION OF RESULTS:
If no microorganism is observed after incubation period then the product
meets the requirement stability of liposomes will improve circulation
time in the blood.

72. Stability study Storage conditions Testing frequency
(Months)
Accelerated
(6 months)
40 + 2C & 75 + 5%
RH
0,1,2,3 & 6
Intermediate
(3 years)
30 + 2C & 65 +5%
RH
0,3,6,9,12,18,24 &
36
Long term
(5 years)
25 + 2C & 60 + 5%
RH
0,3,6,9,12,18,22,24,2
6,36,48 & 60

73. 1.PHYSICAL APPEARANCE OF TABLET
Colour, surface, sticking, cracks etc.
2.TABLET HARDNESS:
It is the load required to crush the tablet when placed on its
edge. Hardness can affect the disintegration. So if the
tablet is too hard, it may not disintegrate in the required
period of time. And if the tablet is too soft, it will not
withstand the handling during subsequent processing such
as coating and packaging.
MONSANTO TESTER: The apparatus consists of 2 jaws
facing each other.
PROCEDURE Measurements is carried out on 10 tabets
taking care to remove all the fragments of the broken
tablets before each determination
LIMITS ranges from 4 – 6 Kg (1 Kg = 10 Newton)

74. 3.Content Uniformity Test:
Randomly select 30 tablets. 10 of these assayed individually. The
Tablet pass the test if 9 of the 10 tablets must contain not less than
85% and not more than 115% of the labeled drug content and
the 10th tablet may not contain less than 75% and more than
125% of the labeled content.
If these conditions are not met, remaining 20 tablet assayed
individually and none may fall out side of the 85 to 115% range.
4.Loss on drying:
Take sample of 10 tablets .crush them and weigh them.this will be there initial
weight.then dry them ,drying will decrease there weight.dry them until the
weight becomes constant .this will be there final weight after drying.then
calculate percentage of moisture content that is lost on drying by following
formula
Initial wt – final wt / initial wt ×100
5.Assay of active ingredient:
Assay of active ingredient is carried out following the method given in
individual monograph for each specific drug.

75. 6. Disintegration Test
 Soluble/effervescence tablets…………………..3-5 min
 Compressed tablets……………………………..15 min
 Film coated………………………………………30 min
 Sugar coated……………………………………..1 hr.
 Enteric coated …………………………………….3hrs
7. Dissolution test:
 The release of drug from the tablet into solution per unit
time under standardize condition is called dissolution test.
mostly 2 types of apparatus are used.
 Apparatus-1 (Basket Type)
 Apparatus -2(paddle type)

76. A substance enclosed under pressure and able to be
released as a fine spray, typically by means of a propellant
gas is called aerosol.
Official Test :
Content uniformity, Uniformity of delivered dose ,Particle size
and Leak test.
Net content :
Weight of empty container =W1 gm Weight of the filled
container = W2gm Difference in the weight = W1-W2gm
net content. Distractive method: weight the filled container,
dispensing the content and then contents are weighed.

77. Dosage With Metered Valve:
 It is tested to ensure reproducibility of dosage each time
the valve is depressed and the amount of medication
actually received by the patient. It is done by assay
method either by spraying the content into the solvent or
on the material which absorb the API, which is then
assayed for the content uniformity.
Particle Size Determination:
 Cascade impector, operates on the principle that a stream
of particles projected through a series of nozzles and glass
slides at high velocity, larger particles became impacted
first on the lower velocity stages and the smaller particles
pass on and are collected at higher velocity stages.
Particle size = 2-8µ.

78.  Leakage test :
Select 12 pressurized containers at random, and record the date and time
to the nearest half-hour. Weigh each container to the nearest mg, and
record the weight, in mg, of each as W1. Allow the container to stand
in an upright position at room temperature for not less than 3 days,
and again weigh each container, recording the weight, in mg, of each
as W2, recording the date and time to the nearest half-hour. Determine
the time, T, in hours, during which the containers were under test.
Calculate the leakage rate, in mg per year, of each container from the
expression. 365 x 24/T x (W1 - W2).
 Flame Projection : Flame projection effect of an aerosol formulation is
tested on an open flame. The product is sprayed for about 4 sec into a
flame. Depending on the nature of the formulation, the flame is
extended, the exact length is measured with a ruler.
 Flash Point : Flash point is determined by using the Standard Tag
Open Cup Apparatus. The aerosol product is allowed to chill to a temp
of about -250F & transferred to test apparatus. The test liquid is
allowed to increase slowly in a temperature & the temp. at which the
vapour ignites is taken as the flash point. It is calculated for flammable
components, mostly in case of topical hydrocarbons.

79.  Aerosol Valve Discharge Rate:
This is determine by taking an aerosol product of known weight and discharge
the content for a given period of time using standard apparatus. By
reweighing the container after the time limit has expired, the change in
weight per time dispensed is the discharge rate, which can then be
expressed as grams per second.
 Spray pattern :
This method is based on the impingement of the spray on a piece of paper that
has been treated with a dye-talc mixture. Depending on the nature of the
aerosol, an oil-soluble or water-soluble dye is used. The particles that
strike the paper cause the dye to go into solution and to be absorbed onto
the paper. These gives the record of the spray, which can then be used for
comparison.
 Foam Stability :
Foam Stability Visual evaluation Time for a given mass is performed to
penetrate the foam. The time for a given rod that is inserted into the foam
to fall Rotational viscometer is determined.
 Light Scatter Decay :
As the aerosol settles under turbulent conditions, the change in the light
intensity of a Tindal beam is measured.

80. Taste (flavour): Mostly combinations of flavouring agents are used in industries. Apart
from this, methanol and chloroform also used as desensitizing agent because they
provide the odour to preparation along with some local anesthetic effect. In food
industries, the monosodium glutamate is mainly used. The change flavoring agent
can be determined by vapour phase chromatography.
Colour: Colour is measured by spectrophotometrically.
Turbidity: Turbidity is measured by using an instrument called a nephelometer with
the detector setup to the side of the light beam. More light reaches the detector if
there are lots of small particles scattering the source beam than if there are few. The
units of turbidity from a calibrated nephelometer are called Nephelometric Turbidity
Units (NTU).
Viscosity: Viscosity of solution serve the palatability or improve portability. This can be
achieved by increasing the sugar content in the syrup or adding viscosity controlling
agents , such as polyvinylpyrolidone and various cellulose derivative like methyl
cellulose or carboxy methyl cellulose.

81. Clarity Test: This test is performed to detect
the particulate matter.
 Visual method
 Microscopic count method
 Light obstruction method
 Coulter counter method
Temperature: Solutions should remain clear at
a relatively wide temperature range such as
4-47c°.

82.  Swirly precipitation
Often a parenteral solution will develop a swirly precipitate upon
storage. vials are placed, then the vials can be examined from
time to time, and one may establish how many vials have
become swirly. The occurrence of swirls is usually a container
interaction, and a change in the stopper or the glass may often
eliminate the problem. Vials should always be stored (a)
upright, (b) on the side, and (c) upside down to check the
interaction with the stopper. In this way primary evidence can be
established as to the culpability of the closure.
 Integrity of container: Some plastic container may shrink when
contact with the preparation or may cause corrosion of cap.
Sometime the glass container may change the pH of solution
and may affect the stability of preparation.