This document discusses quality control testing for semisolid and transdermal drug delivery systems. It describes tests for characteristics like physical appearance, viscosity, homogeneity, pH, weight variation, drug content, and microbial limits for semisolid dosage forms. For transdermal patches, tests include thickness, mechanical strength, moisture content, drug release and permeation. The key quality control tests ensure the products meet specifications for identity, purity, strength and stability.

1. QUALITYCONTROLOFDOSAGE FORMS
Semisolid &
Transdermal Delivery
Systems

2. Introduction
Topical Preparations
• Local action on site of
application e.g. skin, nasal
mucosa
• Semisolid Formulations:
ointments, creams, Gels
Pastes
• Others: Lotions, sprays.
liniments, aerosols etc.
Transdermal
Preparations
• Show systematic effect i.e.
absorbed through skin
into blood and show effect
on other parts of body
• Transdermal Delivery
Systems (TDS): Patches
• Others: Any formulation
applied topically for
systematic action

3. Semisolid Dosage Forms
Semisolid Dosage Forms:
• Semisolid dosage forms are products of semisolid
consistency and applied to skin or mucous membranes for
therapeutic or protective action or cosmetic function
Semisolid Dosage Forms
Ointments Creams Gels Pastes

4. Semisolid Dosage Forms
1. Ointments:
 Ointments are semisolids intended for external application to
the skin or mucous membranes.
 They usually contain less than 20% water and volatiles and
more than 50% hydrocarbons, waxes, or polyols as the
vehicle.
2. Creams
 Creams are semisolid emulsion systems with opaque
appearance compared with the translucent ointments.
 Creams can be w/o or o/w type

5. Semisolid Dosage Forms
3. Gels:
 Gels (sometimes called Jellies) are semisolid systems
consisting of either small inorganic particles or large organic
molecules interpenetrated by a liquid.
 These are transparent, translucent, non-greasy semi solid
preparations
4. Pastes:
 Pastes are semisolid dosage forms intended for topical
application, that contain a high percentage (often > 50%) of
finely dispersed solids with a stiff consistency

6. QC Test of Semisolid Dosage Forms
QC
of
Semisolid
Dosage
Forms
1. Physical appearance
2. Rheological studies
3. Homogeneity Test
4. pH determination
5. Average filling weight
6. Content uniformity
7. Microbial Content
8. Drug Release Test
9. Stability testing
10. Special evaluation tests

7. QC of Semisolid Dosage Forms
1. Physical Appearance
 Examination of the color, odor and other
physical properties of the product e.g. cracking
of creams (separation of oil and water)
2. Rheological Studies
Purpose: to measure the viscosity of the
semisolid preparation
Method: As specified in official monograph
Apparatus: Brookfield viscometer
Brookfield Viscometer

8. QC of Semisolid Dosage Forms
3. Homogeneity Test/ Particle Size
Purpose: To ensure the absence of gritty particles
Procedure:
1. Dilute preparation with glycerol
2. Place on a glass slide and examine under light
microscope
3. Count the number of particles with diameter above or
below than that specified in monograph
4. Compare the percentage with official limits

9. QC of Semisolid Dosage Forms
4. pH determination
Purpose: measured to avoid irritation upon its application to
the skin.
Procedure: Mix one gm of the preparation is mixed with
9mL distilled water & determine the pH
pH Meter

10. QC of Semisolid Dosage Forms
5. Average filling weight
Purpose: To ensure that the product contains the labeled amount
of contents
Procedure:
1. Select 10 filled containers, remove label and weigh
individually
2. Remove the contents of containers and wash.
3. Dry and again weigh each empty and take difference as weight
of contents

11. QC of Semisolid Dosage Forms
5. Average filling weight
Limits:
 For less than 60 g: The net weight of contents of any single
container should not be less than 90% of the labeled amount.
 For 60 to 150g: The net weight of contents of any single
container should not be less than 95% of the labeled amount
 If one container is outside limit repeat test with 20 containers.
The average net weight of contents of 30 containers should
not be less than labeled amount

12. QC of Semisolid Dosage Forms
6. Content Uniformity Test
Purpose:
 To ensure that labelled amount of active ingredient is
present
Procedure:
Assay of active ingredients is performed according to
monograph
Percentage contents should be within the official limits

13. QC of Semisolid Dosage Forms
7. Microbial Contents:
Why Microbial Contents Should be Determined?
 Microorganisms can grow, if no preservative is added
 Even if preservatives are added, its efficiency is reduced due
to interaction with other ingredients
 Therefore, microbial contents should be determined
Methods:
Antimicrobial assay should be performed according to
official monograph, usually
• Direct inoculation method
• Membrane filtration method

14. QC of Semisolid Dosage Forms
8. Drug Release Test (Dissolution):
Purpose: To understand the drug release from preparation
Procedure:
1. A dialysis bag is loaded with 2 gm of semisolid preparation,
suspended in a beaker containing 100 ml of the dissolution at
temperature 37°C & stirred at 100 rpm.
2. Samples are withdrawn at time specified intervals to
determine the amount of the drug in solution.
3. The release results are plotted as concentration versus time
to determine the release profile.

15. QC of Semisolid Dosage Forms
9. Accelerated stability
Purpose:
 It is based on stressing the system, either by temperature
variations or centrifugation to assess its physical stability
(creaming, cracking or separation).
Two tests are mainly performed
1. Freeze-thaw cycling.
Semisolids are stored in an incubator at 50°C for 48 hours &
then transferred to freezer at -5°C for 48 hours, test is
performed for three consecutive cycles

16. QC of Semisolid Dosage Forms
9. Accelerated Stability
2. Centrifugation test.
Used to predict long term
behavior of semisolids.
Centrifugation at 3750 rpm for
5 hours is equivalent to the
effect of gravity for one year.
The centrifuge

17. QC of Semisolid Dosage Forms
10. Special evaluation tests
For ophthalmic ointments:
Sterility testing
 Metal Particle
For creams:
 Determination of the emulsion type (w/o, o/w, w/o/w,
o/w/o.)

18. Transdermal Patches / Films:
 Designed to support the passage of drug substances from the
surface of the skin, through its various layers, and even into
the systemic circulation.
Advantage of TDS:
 The patches provides a controlled release of medication into
the patient
Disadvantage of TDS:
Only used for small molecules which can easily penetrate
because skin in skin has very effective barrier that do not
allow the entry of large molecules.
Transdermal Delivery Systems

19. Components of Transdermal Patches
1. Drug: Drug is in direct contact with release liner
2. Liners: Protects the patch during storage
3. Adhesive: Serves to adhere the patch to the skin
4. Beckoning: Protect patch from outer environment
5. Silicon rubber.
6. Polymer matrix: The polymer controls the release of
the drug from patch
Transdermal Delivery Systems

20. Types of of Transdermal Patches
Transdermal Delivery Systems
Video Link:
https://www.youtube.com/watch?v=HJ1bKtUzeL4

21. 1. Thickness:
Purpose: Transdermal Films should be uniform
in thickness
Apparatus: Thickness is determined by using
screw gauge or micrometer at different points.
QC of Transdermal Delivery Systems
Screw Gauge
2. Folding Endurance:
Purpose: To ensure that film do not break due to folding during
handling
Methods: Films is folded at same place till it break. The No. of
times film can be folded without breaking gives folding.

22. 3. Mechanical Strength Test:
Purpose: To ensure TDS do not break after
application on skin due to stretching or peeling
Apparatus: Universal Testing Machine (UTM)
Procedure:
1. One end of the films is kept fixed and other end
is connected to a moveable shaft
2. The weights are added gradually to moving
shaft until film break
3. The weight required to break film indicates
mechanical strength and percent increase in
strength before breaking indicate flexibility
QC of Transdermal Delivery Systems
Universal Testing
Machine

23. 4. Moisture Content:
 The films are weighed individually and kept in a desiccators
containing calcium chloride at room temperature.
 The films are weighed again after a specified interval until they
show a constant weight and % moisture contents are calculated:
% Moisture content = (Initial weight – Final weight) X 100
5. Uniformity of Weight:
 Weight variation is studied by individually weighing 10 patches
and taking average. The individual weight should not deviate
significantly from the average weight
QC of Transdermal Delivery Systems

24. 6. Content Uniformity Test:
Purpose: To ensure that patch contain labelled amount of drug
Method: assay of the drug is performed according to
monograph. Drug content should be within the official limits
7. Drug Release (Dissolution) Test:
Purpose: To study the drug release behavior from TDS
Apparatus: The Paddle over Disc apparatus is mostly used. It
is similar to USP paddle dissolution apparatus, except that the
TDS is attached to a disc resting at the bottom of the vessel
which contains medium at 37 ±5°C.
QC of Transdermal Delivery Systems

25. 8. In-vitro Drug Permeation Test:
Purpose: To determine the absorption of drug through skin
Apparatus:
 Franz Diffusion Cell (Vertical Diffusion Cell)is used
 Franz Diffusion cell composed of two compartments
1. Donor Compartment:
Contain at membrane (or skin) at the bottom.
2. Receptor Compartment:
Filled with buffer (5-12ml). Buffer is continuously stirred at
600rpm by and temperature is maintained at 37C
QC of Transdermal Delivery Systems

26. QC of Transdermal Delivery Systems
Video Link:
https://www.youtube.com/watch?v=rRDM1qdrBiw

27. 8. In-vitro Drug Permeation Test:
Procedure of Franz Diffusion Cell:
1. Receptor compartment is filled with buffer and temperature is
set at 37C
2. TDS (Patch, film) is applied on membrane
3. Samples are drawn from the receptor compartment after some
time and drug concentration is determined
4. The drug concentration indicate the amount of drug permeated
through membrane (skin) in specified time
QC of Transdermal Delivery Systems