Evaluation of-semisolid-dosage-forms

EVALUATION OF SEMISOLID
DOSAGE FORMS
PRESENTED BY
SARITHA.T
M.Pharm(I-sem)
Pharmaceutics
U.C.P.SC
K.U

CONTENT
 Introduction
 Ideal properties of semisolids
 Categories of semisolids
 Evaluation of ointments
 Evaluation of creams
 Evaluation of suppositories
 conclusion
 references

INTRODUCTION
 Semisolid pharmaceutical systems comprise a body of
products, which when applied to the skin or accessible
mucous membranes tend to alleviate or treat a pathological
condition or offer protection against a harmful environment.
 They have the property to cling to the skin or mucous
membrane for a protracted period of time to exert their
therapeutic effect through protection and occlusion.
 The adhesion is due to their plastic rheological behavior
which allows semisolid to retain their shape and cling as
film until acted upon by an outside force.

 Semisolid dosage forms usually are intended for localized drug
delivery. In the past few years, however, these forms also have been
explored for the systemic delivery of various drugs.
 Semisolids constitute a significant proportion of pharmaceutical dosage
forms.
 They can be applied topically to the skin, cornea, rectal tissue, nasal
mucosa, vagina, buccal tissue, urethral membrane, and external ear
lining.
DEFINITION
 Semisolid dosage forms are dermatological products of semisolid
consistency which are applied to skin or mucous membrane for
therapeutic or protective action or cosmetic function.

IDEAL PROPERTIES OF SEMISOLIDS
PHYSICAL PROPERTIES
 Smooth texture
 Elegant in appearance
 Non dehydrating
 Non gritty
 Non greasy and non staining
 Non hygroscopic
PHYSIOLOGICAL PROPERTIES
 Non irritating
 Do not alter membrane / skin functioning
 Miscible with skin secretion
 Have low sensitization index
APPLICATION PROPERTIES
 Easily applicable with efficient drug release.
 High aqueous wash ability.

CATEGORIES OF SEMISOLID DOSAGE
FORMS
 Ointments
 Creams
 Pastes
 Jellies / Gels
 Suppositories
 Poultices
 Plasters
 Rigid foams
 Glycero-gelatins

 OINTMENTS
Ointments are semisolid preparations meant for external application
to the skin or mucous membrane.
They usually contain a medicament or medicaments dissolves,
suspended or emulsified in the base.
 CREAMS
Creams are viscous emulsions of semisolid consistency intended for
application to the skin or mucous membrane
 O /W type
 W/O type

 PASTES
Pastes are the preparations contain a large amount of finely
powdered solids such as starch and zinc oxide. These are
generally very thick and stiff.
 JELLIES
These are thin transparent or translucent, non greasy
preparations. They are similar to mucilages because they
are prepared by using gums but they differ from mucilages
in having gelly like consistency.
 SUPPOSITORIES
These are meant for insertion in to the body cavities other
than mouth. They may be inserted in to rectum,vagina or
urethra.

 POULTICES
These are also known as cataplasams.They are soft viscous
wet masses of solid substances.
 PLASTERS
These are solid or semi solid masses adhere to the skin
when spread up on cotton felt line or muslin as a backing
material.
 RIGID FOAMS
These are systems in which air or some other gas is
emulsified in liquid phase to the point of stiffening.

EVALUATION OF OINTMENTS
 Content uniformity of drug
 Penetration
 Rate of release of medicament
 Absorption of medicament in blood stream
 Irritant effect:

 Content uniformity of drug
A known weight of ointment is taken and assayed for
amount of the drug.
 Penetration
A weighed quantity of ointment is rubbed over skin for a
given period of time and unabsorbed ointment is collected
and weighed.
The differences in weights represent the amount absorbed.

In Vitro Skin Penetration
 Flow through cell
 Franz diffusion cell
They mainly have two compartments
1) Donor
2) Receptor
Method:
 mouse skin or human cadaver skin.
 Placed in between the two compartments.
 The passage of semisolid preparation through the
epidermal surface to receptor compartment is measured
by,
 Detector ( Flow through type )
 Sampling ( Franz diffusion cell )

RATE OF RELEASE OF MEDICAMENT
 To assess rate of release of medicament, small amount of
the ointment can be placed on the surface of nutrient agar
contained in a Petri dish or alternately in a small cup cut in
the agar surface.
If the medicament is bactericidal the agar plate is previously
seeded with a suitable organism like s.aureus. After a
suitable period of incubation, the zone of inhibition is
measured and correlated with the rate of release.
 Another method for finding out release rate is to smear
internal surface of test tubes with thin layers of ointment,
fill the tubes with saline/serum and after a gap of time
estimating the amount of drug present in the serum/saline.

ABSORPTION OF MEDICAMENT INTO
BLOOD STREAM
 The diadermatic ointment should be evaluated for
the rate of absorption of drug into the blood
stream. This test can be run in-vivo only.
 Definite amount of ointments should be rubbed
through the skin. Under standard conditions and
medicaments are estimated in the blood plasma or
urine.

IRRITANT EFFECT
 In general no ointment should possess irritant effect on the
skin or mucous membranes the tests for irritancy can be
carried out on the skin and eyes of rabbits or the skin of
human beings.
 The irritant effect can also be judged to a certain extent by
injecting the ointment into thigh muscles and under the
abdominal skin of rats. Reaction are noted at intervals of
24,48,72 and 96 hours. Lesions on cornea, iris, conjunctiva
are used for judging the irritancy to the eyes. Presence of
patches on the skin within 2 weeks indicate irritancy to
pressing skin.

DRAIZE TEST
 Draize skin irritation test:
 A known amount of test substance is introduced
under a one square inch gauge patch,
 The patch is applied to skin of 12 albino rabbits,
(6 with intact skin) and (6 with abraded skin),
 The patch is secured in place with adhesive
tape and the entire trunk of the animal is
wrapped with an impervious material for a 24
hour period,
 After 24 hours the patches are removed and
resulting reaction is evaluated for erythema and
edema formation.
 The reaction is again scored at the end of 72
hours and the two readings are averaged.

CONCLUSION FROM DRAIZE TEST
CATEGORY
DRAIZE
CODE SKIN REACTION
Mild MLD Well defined erythema and slight
edema ( edges of area well defined
by definite raising)
Moderate MOD Moderate to severe erythema and
moderate edema (area raised
approximately 1 mm)
Severe SEV Severe erythema (beet redness to
slight eschar formation (injuries in
depth ) and severe edema ( raised
more than the 1 mm and extending
beyond area of exposure.

DRAIZE EYE IRRITATION TEST
 A known amount of test material is placed in one eye
of each of 6 albino rabbits the other eye remains
untreated, serving as a control.
 The eyes are not washed after instillation and are
examined at 24,48 and 72 hours for ocular reaction.
 The test is considered positive if ulceration, opacity of
the cornea , inflammation of the iris, swelling of the
conjunctiva occurs.
 A substance is an eye irritant if,
 4 of six rabbits score positive
 it is considered a non irritant if none or only one of the
6 animals exhibit irritation.

CONSISTENCY TEST
 PENETROMETRY:
 PROCEDURE:
Preparation of test sample: 3 methods (A,B,C)
 A: Carefully and completely fill three containers without
forming air bubbles. Level if necessary to obtain a flat
surface.
 B: Apply a suitable shear to the samples for 5 min
carefully and completely fill three containers without
forming air bubbles. Level if necessary to obtain a flat
surface.
 C: melt 3 samples carefully and completely fill three
containers without forming air bubbles. Level if
necessary to obtain a flat surface.
CAUTION: Store the samples at 25 ± 0.5oC foe 24 h0urs
unless otherwise prescribed.

Determination Of Penetration :
Place the test sample on the basis of the
penetrometer. Verify that its surface is
perpendicular to the vertical axis of the
penetrating object. Bring the temperature of
the penetrating object to 25 ± 0.5oC and then
adjust its position such that its tip just touches
the surface of the sample . Release the
penetrating object and hold it free for 5 sec.
clam the penetrating object and measure the
depth of penetration. Repeat the test with 2
remaining containers.

RESULT:
The penetration is expressed in
terms of mm as the arithmetic mean
of the three measurements. If any of
the individual results differ from the
mean by more than 3%,repeat the
test and express the results of the 6
measurements as the mean

EVALUATION OF CREAMS
As these products are used widely and for various parts of the
body, stringent evaluation and quality control is essential.
Appearance spread ability, wash ability.
 Rheology
Rheology is very important as these creams are marketed in
tubes or containers. The rheology or viscosity should remain
constant. As these products are normally non-Newtonian in
nature, the viscosity can be measured using viscometers
used for such liquids.

Rheologic measurements are utilized to characterize the
ease of pouring from a bottle, squeezing from a tube or
other deformable container, maintaining product shape in a
jar or after extrusion rubbing the product onto and into the
skin and pumping the product from mixing and storage to
filling equipment.

 Sensitivity
As various types of ingredients are used with occasional use
of antiseptics hormones etc. there is a possibility of
sensitization or photosensitization of the skin. This should
be tested before hand. This test is normally done by patch
test on and can be either open or occlusive. The test sample
is applied along with a standard market product at different
places and effect is compared after a period of time.

EVALUATION OF SUPPOSITORIES
 Appearance
 Uniformity of weight
test
 Melting rang test
 Liquefaction test
 Breaking test
 Dissolution test

Appearance
 The suppository when cut longitudinally and examined with
the naked eye the internal and external surfaces of the
suppository should be uniform in appearance.
 Compliance with the standard indicates satisfactory
subdivision and dispersion of suspended material.
 Surface appearance and colour can be verified usually to
assess absence of fissuring, absence of fissuring, absence of
pitting, absence of exudation, absence of migration of the
active ingredients

Uniformity of weight test
 To perform this 20 suppositories are weighed and average
weight is calculated.
 Then each suppository is weighed individually and weight
noted.
 No suppository should deviate from the average weight by
more than 5%except that two should not deviate by more
than 7.5%.
 The weight variation may result if some cavities are under
filled and other are overfilled.

Melting Range Test
 This test is also called the macro melting range test and is a
measure of the time it takes for the entire suppository to
melt when immersed in a constant-temperature (37oC)
water bath.
 In contrast, the micro melting range test in the melting
range measured in capillary tubes for the fat base only. The
apparatus commonly used for measuring the melting range
of the entire suppository is a USP Tablet Disintegration
Apparatus.
 The suppository is completely immersed in the constant
water bath, and the time for the entire suppository to melt or
disperse in the surrounding water is measured.

 The in vitro drug release pattern is measured by using the
same melting range apparatus. If the volume of the water
surrounding the suppository is known, then by measuring
aliquots of the water for drug content at various intervals
within the melting period, a time-versus-drug content curve
(in vitro drug release pattern) can be plotted.

Liquefaction or Softening Time Tests of Rectal
Suppositories.
 A Modification of the method developed by krowcynski is
another useful test of finished suppositories. It consists of a
U-tube partially submersed in a constant- temperature water
bath.
 A constriction on one side hold the suppository in place in
the tube. A glass rod is placed on top of the suppository,
and the time for the rod to pass through to the constriction
is recorded as the softening time.
 This can be carried out at various temperatures from 35.5 to
37oc, as a quality control chek and can also be studied as a
measure of physical stability over time. A water bath with
both cooling and heating elements should be used to assure
control with 0.1oc.

Breaking test
 Brittleness of suppositories is a problem for which various
solutions have already been described. The breaking test is
designed as a method for measuring the fragility or
brittleness of suppositories.
 The apparatus used for the test consists of a double-wall
chamber in which the test suppository is placed. Water at
37oc is pumped through the double walls of the chamber,
and the suppository contained in the dry inner chamber,
supports a disc to which a rod is attached.
 The other end of the rod consists of another disc to which
weights are applied. The test is conducted by placing 600 g
on the platform.

 At 1-min intervals, 200-g weights are added, and the weight
at which the suppository collapses is the breaking point, or
the force that determines the fragility or brittleness
characteristics of the suppository.
 Differently shaped suppositories have different breaking
points. The desired breaking point of each of these
variously shaped suppositories is established as the level
that withstands the break forces caused by various types of
handling i.e., production, packaging etc.

Dissolution Testing
 Testing for the rate of in vitro release of drug substances from
suppositories has always posed a difficult problem, owing to
melting deformation, and dispersion in the dissolution
medium. Early testing was carried out by simple placement in
a beaker containing a medium.
 In an effort to control the variation in mass or medium
interface, various means have been employed, including a wire
mesh basket, or a membrane, to separate the sample chamber
from the reservoir.
 Samples sealed in dialysis tubing or natural membranes have
also been studied. Flow cell apparatus have been used, holding
the sample in place with cotton, wire screening and most
recently with glass beads.

CONCLUSION
 Most of the semisolid preparations are
applied to the skin or mucous membranes
such as rectal,urethral,vaginal,nasal mucosa
and cornea.So,semisolid preparations must
be evaluated.

REFERENCES
 James swarbrick ,James C.Boglan Encyclopedia of
Pharmaceutical Technology,volume 6.
 B.M.Mithal,Pharmaceutical formulations.
 S.J.Carter.Dispensing for Pharmaceutical Students.
 Gilbert S Banker and Christopher T.Rhodes-
Modren Pharmaceutics 3rd Edition.
 European pharmacopoeia

 Herbert A.Lieberman,Martin M.Riger and Gilbert
S.Banker’Pharmaceutical Dosage forms Volume-2.
 www.bepex.com
 Cooper and Guns,Dispensing and Community Pharmacy
12th Edition
 www.pharmaceutical-equipment.com
 www.pharmainfo.net
 www.biteba.com

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