This document provides an overview of transdermal drug delivery systems (TDDS). It defines TDDS and lists their advantages over other delivery methods. The basic components of TDDS are described, including polymer matrices, drugs, permeation enhancers, and other excipients. Several formulation approaches for TDDS are outlined, such as membrane permeation-controlled systems and matrix diffusion-controlled systems. Methods for evaluating TDDS are mentioned, including drug-excipient interaction studies, weight uniformity testing, percentage moisture content testing, drug content analysis, moisture loss testing, and skin irritation testing. The document concludes by citing two review articles on TDDS.

1. WEL
-COME

2. Presented by : Miss . Supriya Wable.
M.Pharm,1st Year
Dept : Pharmaceutics
Dattakala collgege of pharmacy
Date:

3.  Introduction
 Advantages
 Basic components
 Formulation approaches used in TDDS
 Evaluation of TDDS
 Reference

4.  Definition –
Transdermal therapeutic systems are defined as self
contained ,self discrete dosage forms ,which when
applied to the intact skin deliver the drug at a
controlled rate to the systemic circulation.
 A simple patch that you stick onto your skin like an
adhesive bandage, which utilize passive diffusion of
drugs across the skin as the delivery mechanism.

5.  It delivers a steady infusion of the drug over an
extended period of time .
 Adverse effects and therapeutic failures can be
avoided
 It increases the therapeutic value of many drugs by
avoiding specific problems associated with the drug .
 The simplified medication regimen leads to an
improved patient compliance and reduce inter patient
and intra patient variability.
 Self medication is possible with this type of system.

6.  The components of the transdermal drug delivery
system include –
1. Polymer matrix or matrices
2. The drug
3. The permeation enhancers
4. Other excipients

7. 1.Polymer matrix
 It releases the drug from the device and should
satisfy the following criteria-
ii. Molecular weight , chemical functionality of the
polymer should be such that specific drug diffuses
properly and gets released through it.
iii. It should be stable , non reactive with the drug,
easily manufactured and fabricated into the desired
productiv.
The polymer and its degradation products must be non
toxic or non antagonistic to the host .

8. 2.Drug
Biological properties –
 The drug should be potent with a daily dose of order of
a few mg/ day.
 The half life of the drug should be short.
 The drug must not induce a cutaneous irritant or
allergic response.
 Drugs degraded in the GIT or inactivated by the
hepatic first pass are suitable candidates for
transdermal drug delivery.

9. 3.Permeation enhancers
 These are compounds which promote skin
permeability by altering the skin as a barrier to the
flux of the desired penetrant .
 The flux of the drug (J) is given by-
J= dc J D dx
D= diffusion coefficient
C = conc. of the diffusing species
X= spatial coordinate

10. 4. Other excipients
Adhesives –
 The fastening of the transdermal device is usually
done by the adhesive .
 The adhesive should satisfy the following criteria .
 Do not irritate or sensitize the skin.
 Adhere to the skin during the dosing interval.
 It should be easily removed .
 It should not leave any unwashable residue.

11. Backing membrane
 They are flexible and provide a good bond to the drug
reservoir , prevent the drug from leaving the dosage
form through top.
 It is an impermeable membrane that protects the
product during the use on the skin.• Contains
formulation throughout shelf-life and during wear
period• Must be compatible with formulation
(nonadsorptive)
 Printable
 Eg: metallic plastic laminate , plastic backing with
adsorbent .

12. 1. Membrane permeation – controlled systems
2. Adhesive dispersion – type systems.
3. Matrix diffusion – controlled systems.
4. Microreservoir type or Microsealed dissolution –
controlled systems.
5. Poroplastic – type systems.
6.Transdermal delivery of Macromolecules.

13. 1.Membrane permeation – controlled systems
The drug reservoir is totally encapsulated in a
shallow compartment moulded from a drug –
impermeable metallic plastic laminate & a rate
controlling polymeric membrane which may be
microporous or non-porous.
The rate of drug release from this type of TDDS can
be tailored by varying the composition of polymer,
permeability coefficient, thickness of the rate limiting
membrane & adhesive.

15. 2.Adhesive dispersion – type systems
The drug reservoir is formulated by directly
dispersing the drug in an adhesive polymer & then
spreading the medicated adhesive by hot melt, on to a
flat sheet of drug impermeable metallic plastic
backing to form a thin drug reservoir layer.
Example: Isosorbide dinitrate-releasing Transdermal
therapeutic system (Frandol tape) for once a day
medication of angina pectoris.

17. 3. Matrix diffusion – controlled system
i) It is prepared by homogeneously dispersing the drug
particles with a liquid polymer or a highly viscous base
polymer followed by cross linking of the polymer chains or
homogeneously blending the drug solids with a rubbery
polymer at an elevated temp.
ii) It can also be prepared by dissolving the drug & polymer in
a common solvent followed by solvent evaporation in a
mould at an elevated temp. or in a vaccum.
iii) It is then pasted on to an occlusive base plate in a
compartment fabricated from a drug impermeable plastic
backing, the adhesive polymer is then spread along the
circumference to form a strip of adhesive rim around the
medicated disc.

19. 4. Microreservoir type or Microsealed dissolution –
controlled systems
 This is the combination of reservoir & matrix
diffusion type drug delivery systems.
 Drug reservoir is formed by first suspending the drug
solids in an aqueous solution of a water soluble liquid
polymer & then dispersing the drug suspension
homogeneously in a lipophilic polymer such as silicone
elastomers by high dispersion technique.
 Example: Nitroglycerine-releasing Transdermal
system (Nitro disc) for once a day therapy of angina
pectoris.

21. 5. Poroplastic– type systems
 It is made utilizing the concept of the water
coagulation of cellulose triacetate solution in organic
acids at low temp.
 The coagulation is performed under controlled
condition.
 The water may be exchanged subsequently for
another vehicle by a diffusional exchange process, &
hence it is also known as “solid composed mostly of
liquid.”

22. 6. Transdermal delivery of Macromolecules
 Macromolecules such as Hormones, interferons,
bioactive peptides can be deliver by Transdermal
delivery system.
 The devices used for this purpose are divided in to two
categories…. a. Devices based on ethylene vinyl
acetate copolymers (EVAc).
 Devices based on silicone elastomers.
 This both the systems utilize one common concept i.e.
matrix must have channels to facilitate the release of
macromolecules.
 These devices are used as implants.

23. 1.Drug excipient interaction studies
Interaction studies are commonly carried out using
thermal analysis, FT-IR studies, UV and
chromatographic techniques by comparing their
physicochemical characters such as assay, melting
endotherms, characteristic wave numbers and
absorption maxima etc.

24. 2.weight uniformity
The prepared patches are dried at 60o c for 4 hrs
before testing.
A specified area of patch is to be cut in different parts
of the patch and weight in digital balance.
The avg weight and standard deviation values are to
be calculated from the individual weights.

25. 3.percentage moisture content
The prepared patches are cut into strips of specific
size. The strips are then weighed individually and kept
in a dessicator containing activated silica at 300c for 12
hrs. The films are reweighed individually until a
constant weight is obtained.
%moisture content =loss in wt/initial wt ×100

26. 4.drug content
The specified films are to be dissolved in a suitable
solvent in specific volume.
Then the solution is to be filterd through a filter
medium and analyze the drug contain with the suitable
method.
Each value avg of three different samples.

27. 5. Moisture loss
The prepared films are to be weighed individually
and to be kept in a dessicator containing calcium
chloride at 40c .
After 24 hrs the films are to be reweighed and
determine the percentage of moisture loss from the
below formula.
%moisture loss =initial wt -final wt /final wt ×100

28. 6. Skin irritation test
This test can be performed on healthy rabbits.
The dorsal surface of the rabbit is to be cleaned and
remove the hair from the clean dorsal surface by shaving
and clean the surface by using rectified spirit and the
representative formulations can be observed and
classified into 5 grades on the basis of the severity of skin
injury.

29.  Anna M wokovich,suneela proddutari ,willam H
doub; review article on transdermal drug delivery
system by European journal of pharmaceutics and
biopharmaceutics, 2006.
 Mark Road prausnitz; reviews article on
microneedles forum transversal drug delivery by
advanced drug delivery reviews,2004.

30. Thank you