This document discusses topical routes of drug administration and dosage forms. It defines topical administration as applying a drug formulation to the skin or mucous membranes to treat local disorders. There are two types - external applications spread on the skin, and internal applications to body openings. Dosage forms include solids, liquids, and semi-solids like ointments, creams, gels, and lotions. Factors like drug properties and vehicle composition affect skin absorption rates. Topical formulations provide localized treatment while avoiding first-pass metabolism and other issues of oral medications.

1. Topical Route of Drug
Administration And
Dosage Forms
Dr. Mansij Biswas, FYR
Department of Pharmacology & Therapeutics
Seth G S Medical College & KEM Hospital
1

2.  defined as the application of a drug containing
formulation to the skin or mucous membrane, to treat
specific cutaneous disorders (e.g. acne) or cutaneous
manifestations of a generalised disease (e.g.
psoriasis), with the intent of containing the
pharmacological effect of the drug only to the surface
or within the layers of skin or mucous membrane.
Ansel H.C., Allen L.V., “Pharmaceutical Dosage Forms and Drug Delivery System”, 7th edition, Lippincott
Willlams and Wilkens, Baltimore, 2000, 244-246,249-251, 253-255,264-265
2

3.  Includes two basic types:
A) External- that are spread or dispersed on the cutaneous surface
covering the affected area.
B) Internal- that are applied to the mucous membrane of eye
(conjunctiva), ear, oropharyngeal cavity, nasal cavity, vagina
or anorectal region for local activity.
Classification Based on physical state-
(A) Solid:
Powder, Aerosol, Plaster
(B) Liquid:
Lotion, Liniment, Solution, Emulsion, Suspension, Aerosol
(C) Semi-solid:
Ointment, Cream, Paste, Gel, Jelly, Suppository
3

4. Advantages of Topical Drug
Delivery System:
Avoidance of first pass metabolism
Easy application
Avoidance of the risks and inconveniences of administration and the
varied conditions of absorption, like pH changes, presence of
enzymes, gastric emptying time etc in enteral or parenteral routes
Achievement of efficacy with lower total daily dosage of drug by
continuous drug input
Avoids fluctuation in drug levels, inter- and intra-patient variations
Easy termination of medications, when needed
4

5. Advantages: contd…
Relatively large area of application
Drug can be delivered more selectively to a specific site
Avoidance of gastro-intestinal incompatibility
Provide utilization of drugs with short biological half-life &
narrow therapeutic window
Improved physiological and pharmacological response
Improved patient compliance
Suitable for self-medication
Surver, C. and Davis, F.A., Bioaviability and Bioequivalence, In Walter, K.A..(Ed. ) , Dermatological and Transdermal
Formulation, Marcal Dekker, INC. NewYork , 119,2002,pp. 403,323,326,327,403
5

6. Disadvantages of Topical Drug
Delivery System:
Skin irritation/contact dermatitis due to drug and/or excipients
Poor permeability of some drugs through the skin
Possibility of allergic reactions
Can be used only for those drugs which require low plasma
concentration for action
Enzymes in epidermis may denature the drugs
Drugs with larger particle size are difficult to get absorbed
through the skin
6

7. Cross Section of Human Skin:
7

8. Absorption through skin:
Two principal absorption route are identified:
A) Trans-epidermal absorption:
Principally responsible for diffusion across the skin. The resistance
encountered along this pathway mostly arises in the stratum corneum.
Maybe trans-cellular or inter-cellular.
B) Trans-follicular (shunt pathway) absorption:
The skin’s appendages, mainly sebaceous glands, sweat glands, hair
follicles offer secondary avenues for permeation, which are considered as
shunts bypassing the trans-epidermal route.
 Basic principle of permeation-initial
transient stage- shunt pathway predominates, but when a steady state has been
reached, diffusion through stratum corneum becomes the dominant pathway.
8

9. Factors Affecting the Extent and Rate of
Topical and Percutaneous Drug Absorption
and Transportation:-
 skin physiology & pathology:- hydration, blood flow, lipid content
 physico-chemical properties of drugs and excipients:-
• Partition coefficient
• pH-condition
• Drug solubility
• Concentration
• Particle size
• Polymorphism
• Molecular weight
 fabrication and design of the delivery systems:-
release characteristics, composition, nature of vehicle, presence of penetration
enhancers
The rate of drug transport across the stratum corneum follows Fick’s Law
of Diffusion
9

10. Topical Dosage Forms:-
Ointment:-
Viscous semisolid preparation
Applied externally to skin or mucous membrane (eye, nose,
vagina, rectum)
10

11. Vehicle of an ointment is known as ointment base
1) Hydrocarbon (oleaginous) bases:
Emollient, occlusive, greasy, non water washable, prolonged contact period
E.g.- white/yellow petrolatum
2) Absorption (anhydrous) bases:
Permits the incorporation of additional quantities of aqueous solutions
E.g.- Lanolin
3) Water removable Bases:
Oil in water type, non occlusive, less greasy, creamy in appearance, water-washable.
4) Water soluble Bases:
Do not contain oleaginous components, completely water-washable, greaseless, mostly
used for the incorporation of solid substances.
E.g.- Polyethylene Glycol
5) Simple base:
Wool fat (5%) + hard paraffin (10%) + yellow soft paraffin (85%)
11

12. Evaluation
of ointments
Penetration
Rate of release of
medicaments
Absorption of
medicaments into
blood stream
Irritant effect
12

13. 13
Methods of preparation of ointments:
a) Trituration: finely subdivided insoluble medicaments are
evenly distributed by grinding with a small amount of the
base followed by dilution with gradually increasing amounts
of the base.
b) Fusion: the ingredients are melted together in descending
order of their melting points and then stirred to ensure
homogeneity.
 Difficult to measure precise dose- by weighing the tube before
& after use or measuring the length of the ribbon squeezed.
 Only the medicine that is touching the skin will work, so thin
layer is always preferred to thick layer.

14. Cream:
Viscous semisolid emulsion- medicaments dissolved or suspended in
water removable bases.
Applied to skin or mucous membrane (vagina, rectum)
 Most are O/W (small droplets of oil dispersed in a continuous
aqueous phase), only cold creams and emollients are W/O (small
droplets of water dispersed in a continuous oily phase).
 O/W (vanishing) - water washable, non greasy, non occlusive, more
cosmetically acceptable.
W/O (oily) - for some hydrophobic drugs, more emollient.
14

15. Advantages over ointment:-
1. Less greasy
2. Spreads easily
3. Soothing sensation
4. Easily washable
• Uses:-
1. Physical or chemical barrier to protect the skin e.g. sunscreens
2. Cleansing agent
3. Emollient
4. Retention of moisture (especially water-in-oil creams)
5. Vehicle for drug substances such as local anaesthetics, anti-inflammatory
agents, hormones, steroids, antibiotics,
antifungals or counter-irritants
15

16. 16
Evaluation of
cream
Rheology
Sensitivity
Biological
testing

17. Paste:-
 Pastes are basically ointments into which a high percentage of
insoluble solids have been added
Less greasy than ointments
 Provide protective coating on skin due to it’s stiff consistency
 Poorly occlusive, so suited for application around moist areas
Absorb secretion from the oozing lesions
 Forms an unbroken, water impermeable, opaque film on the skin
17
 Effective sun filter & prevent excessive wind dehydration (windburn)

18. Evaluation of
paste
Abrasiveness
Particle size
Cleansing
property
Consistency
pH of the
product
Foaming
character
Limit test for
arsenic and lead
Volatile matters
and moisture
Effect of special
ingredients
18

19. Gels & Jellies:
Semisolid systems- dispersions of small or large molecules in an
aqueous liquid vehicle by addition of gelling agent
Gelling agents- either Synthetic macromolecules (Carbomer 934) or
Cellulose derivatives (Carboxymethylcellulose)
 Non greasy, moisture rich
Compatible with many substances
 May contain penetration enhancers for anti-inflammatory and some
other medications
19

20. Types:-
·Single phase: macromolecules are uniformly distributed throughout a
liquid with no apparent boundaries between the dispersed macromolecules
and the liquid.
·Double phase: Gel mass consists of floccules of small distinct particles,
often referred to as a magmas.
Gel rich in liquid is called jelly
 Prepared from either natural gums such as pectin, alginate etc. or from
synthetic derivatives of natural substance such as methylcellulose
20

21. Applications:
 sustained-release delivery system
 dressings for healing of burn or other hard-to-heal wounds
 reservoirs in topical drug delivery, particularly ionic drugs,
delivered by iontophoresis
e.g. Diclofenac gel, Lignocaine jelly
21

22. 22
Evaluation
of gel
Drug content
Homogeneity
of drug
content
Measurement
of pH
Viscosity
Spreadability
Extrudability

23. Lotion:
 Clear solution/suspension/emulsion containing 25-50% alcohol
 Low to medium viscosity
May contain extract of witchhazel, menthol, glycerin, boric acid,
alum, chloroform etc but NOT camphor
 Applied without friction
 Can be applied on abraded/wounded skin or on mucous membrane
 Antiseptic, anti inflammatory, astringent, emollient, cooling,
moisturizing or protective actions
e.g. Calamine lotion
23

24. 24
Evaluation
of lotion
Antiseptic
property
Determination of
alcohol content

25. Liniment (Balm):
Low- to medium-viscosity emulsions
 Formulated from quickly evaporating solvents, contain aromatic
chemical compounds
 As a rule contain camphor
 Always applied with friction
 Applied only on unbroken skin, never on mucus membrane
Mechanism of action:
• Rubefacient
• Local irritant
• Counter irritant
Typically used to relieve pain and stiffness such as from sore muscle
cramp or arthritis
 e.g. Turpentine
25

26. Poultices/Cataplasms:-
 Now obsolete
 Heated & spread on dressing & applied as hot as the patient can bear
 Heat is retained, soothing in pain and inflammation
 Ingredients may have counter-irritant/ absorptive properties
 e.g. Kaolin poultice
26

27. Solution:
 Solutions are liquid preparations of soluble chemicals dissolved in
solvents such as water, alcohol or propylene glycol
E.g:
· Tincture of iodine
· Sterile Indian ink for surgical procedures
27

28. Emulsion:
 Two-phase preparations - the dispensed (internal) phase is finely
dispersed in the continuous (external) phase
 Because there are two incompatible phases in close conjunction, a
physical stabilizing system is needed- surfactant (ionic or nonionic),
polymers, polyelectrolytes etc
 Types-
· Water-in-oil emulsion
· Oil-in-water emulsion
· Water-in-oil-in-water emulsion
· Oil-in-water-in-oil emulsion
28

29. 29
Evaluation of
emulsions
Phase separation
Globule size
Rheological
properties
Effect of thermal
stresses

30. Suspension:
 Heterogeneous system consisting of two phases:
1. The continuous or external phase is generally a liquid or semisolid
2. The disperse or internal phase is made up of particulate matter that
is dispersed throughout the continuous phase
 Almost all suspension systems get separated on standing, the rate of
settling and ease of resuspendability is the concern
 A satisfactory suspension must remain sufficiently homogenous for at
least the time necessary to remove and administer the dose after shaking
its container
 Types:
· Flocculated
· Deflocculated
30

31. Evaluation of
suspension
Sedimentation
volume
Rheologic
methods
Electrokinetic
techniques
Particle size
changes
31

32. Medicated shampoos:-
e.g. Selenium sulphide, Cetrimide, Ketoconazole
Paints:-
 Applied to broken skin/mucus membrane
 Applied in throat with an applicator
 e.g. Mandl’s paint
Nail lacquers:-
e.g. Amorolfine (a newer antifungal) for tinea unguium
32

33. 33
Collodion:-
• Protective, occlusive, water repellant film on the skin
surface following evaporation of the solvent
• Seals small cuts and scratches
• Occlusion prolongs contact with active medicaments
• Contains pyroxylone (a nitrocellulose) in an ether alcohol
mixture
• Applied using a brush or applicator
• e.g. Salicylic acid collodion

34. Eye/Ear Drops:-
 Solution/ suspension
 Relatively brief contact time with absorbing surface
 pH, tonicity, viscosity important for local comfort.
 Sterile; require aseptic handling
 Use droppers with attached or separate plastic nozzle, avoid touching
the application surface
 Use: to prevent or treat infections
 E.g. Ciprofloxacin eye/ear drop, Artificial tear
34

35. Ophthalmic strips:-
 Used for delivering diagnostic
dyes topically for eye, by simply
touching the conjunctival surface
 e.g. Fluorescein sodium
Ocular insertion:-
 Continuous release multilayered
polymeric insertion in
conjunctival fornix
 Ocusert (pilocarpine- for
treatment of glaucoma), Lacrisert
(artificial tear substitute- for
treatment of dry eye)
 Not available in India
31

36. Medicated plaster, dressing, sticks:-
36
Belladonna plaster, Keratolytic plaster, neocapsicum plaster
Framycetin dressing

37. Suppository:
Solid dosage forms intended to deliver medicine into rectal,
vaginal or urethral orifice
Prepared by cold compression or fusion technique
An appropriate base is selected for its compatibility, stability,
melting point, and aesthetics. Commonly used bases are cocoa
butter, glycerin, hydrogenated vegetable oils, and polyethylene
glycol
37

38. Advantages:
 Bypasses first pass metabolism
 Suitable when oral route cannot be used (e.g. patient unconscious,
excessive nausea, vomiting, malabsorption disorder)
 Suitable when drug is not suitable for oral use (unstable in GI tract,
degraded by digestive enzymes )
Disadvantages:
 Absorption slower & unpredictable (BA ~50%)
 Inconvenient & embarrassing
 The contained fat often melts at the high temperatures of the tropics
 Used in kids only where controlled delivery possible
38

39. 39
Rectal Suppository:
 Tapered at one or both ends (torpedo shape is most common),
weight= 2g
 They are meant for local (e.g. OTC preparation for hemorrhoids
containing a moisturizer or vasoconstrictor; Glycerin or Bisacodyl
as laxative ) and for systemic (e.g. Paracetamol, Aminophylline,
Promethazine) effects
 Active ingredient(s) usually mixed with a suitable base which is
solid at room temperature to assist insertion, but melts at body
temperature to enable dispersion

40. Vaginal suppositories/pessaries:
 Globose or oviform, weight=5g
 Mostly meant for local effects (clotrimazole, miconazole, metronidazole)
Urethral suppository/bougies:
 Cylindrical, longer for males than for females, obsolete now a days
40

41. 41
Evaluation of
suppository
Melting range
test
Dissolution
test
Liquefaction or
softening time
test

42. Douche:-
 Douche is a device used to rinse any
body cavity but usually applies to
vaginal irrigation
 Vaginal douches may consist of water,
water mixed with vinegar, or even
antiseptic chemicals
 Disadvantage: Can lead to irritation,
pelvic inflammatory disease (PID),
fertility problems
 Use - Treatment of bacterial vaginosis
with a vaginal douche containing a
strain of L. acidophilus
42

43. Medicated Vaginal Rings:-
 Doughnut-shaped polymeric drug delivery devices designed to provide controlled
release of drugs to the vagina over extended periods of time
 Vaginal ring products are used for the treatment of vaginal atrophy, relief of hot
flashes and as a contraceptive
 Vaginal ring technology is currently being developed for the controlled release of
microbicides and vaccines for the prevention of HIV/HPV infection
43

44. Intra uterine Devices:-
 An intrauterine device is a small
contraceptive device, often 'T'-
shaped, containing either copper
(Cu-T) or levonorgestrel (LNG-IUS),
inserted into the uterus
 most effective types of reversible
birth control
44

45. Aerosol:
 A system that depends on the power of compressed or liquefied gas to expel the
contents from the container.
 Topical pharmaceutical aerosols utilize hydrocarbon (propane, butane, and
isobutene) and compressed gases such as nitrogen, carbon dioxide, and nitrous
oxide.
Advantages:
• Rapid onset
• at site delivery
• Less amount of drug required
• Less systemic absorption – less side effects
• No first pass effect
• Dose titration possible
• Acceptable & convenient to patient
45

46. Disadvantages:
• Difficult to maintain particle size ≈ 2-8 microns and moisture content ≈ 100-300
ppm
• Only 10-20% drug is deposited at site
• Aerosol droplets facilitate microbial invasion
• Propellants can cause ADR
• Proper technique is difficult to maintain
Devices:
 MDI ± Spacer
 Nebuliser
 Rotahaler
 Inhaled insulin device
46

47. 47
Evaluation of aerosol
Flame projection
Flash point
Vapor pressure
Density
Moisture
Aerosol valve discharge
rate
Spray patterns
Dosage with metered valves
Net contents
Foam stability
Particle size determination

48. Dusting Powder:-
 Free flowing
 Applied on skin, wounds, ulcers
Very fine particle size produces large surface area per unit weight
 Mechanical protective action against irritation/itching due to friction
 Dries the skin by absorbing water & adsorbs toxic material
 Medicated powders are used for prickly heat or preventing
microbial growth on skin
e.g. Starch, Talc
48

49. 49
Evaluation of powder
Shade control and lighting
Pressure testing
Breakage test
Flow property
Particle size and abrasiveness
Dispersion of color

50. Intranasal Drug Delivery:-
 This route involves administration of drugs directly into the nose
 Agents include nasal decongestants such as xylometazoline &
corticosteroid like mometasone furoate.
 Desmopressin is administered intranasally in the treatment of diabetes
insipidus
 Calcitonin, a peptide hormone used in the treatment of osteoporosis, is
also available as a nasal spray
 Ketorolac nasal spray for pain management
 The abused drug, cocaine, is generally taken by intranasal sniffing
 Applied via drops/sprays/powder or aerosols
 Advantages of nasal delivery
• Lower dose needed
• More rapid attainment of therapeutic blood levels
• Quicker onset of pharmacological activity
• Fewer side effects
50

51. Transdermal Drug Delivery
System (TDDS):-
51

52. 52
Topically administered medicaments in the form of patches or other
techniques, that deliver drugs for systemic effects at a
predetermined and controlled rate.
Transderm Scop® Patch, Novartis,1979- first FDA approved-opened
the door to the current TDDS as a successful alternative to
systemic drug delivery.
TDDS use the percutaneous route for systemic drug delivery, but
the skin is not the primary target organ, active ingredient is moved
across the layers of skin for subsequent systemic distribution.

53. Advantages of TDDS:-

Consistent serum drug levels as IV
 The lack of peaks in plasma concentration
Drugs that require relatively consistent plasma levels are very good
candidates
 Convenience and high adherence
• non invasive
• usually once weekly /once in 15/30 days application
• removal of the patch in case of toxicity
 Avoids FPM and GI irritation
 Great advantage in patients who are nauseated or unconscious
 Useful for drugs that are degraded by the enzymes and acids in the
gastrointestinal system
53

54. Disadvantages:-
 local irritation
• rotation to minimize
• if severe allergic reactions- discontinue
 skin's low permeability limits the number of drugs that can be
delivered
 after removal, most patches contain at least 95% of the total amount
of drug initially in the patch
- patients must exercise care when disposing of patches
Damage to a transdermal patch
• patients should be advised to discard a patch if the outer
packaging or the patch itself appears damaged or altered in any
way
54

55. Design of TDDS:
 Patch design is the first & commonest type
 Factors influencing:-
1. Properties of the drug- Systemic absorption of transdermal is better
with
• low dose
• low molecular weight
• lipid soluble drugs
2. Desired delivery profile
3. Target patient group
-- determine which design is best for a given application
55

56. Components of a TD patch:-
 Liner - protects the patch during storage, removed prior to use
 Drug reservoir- drug solution in direct contact with release liner
 Adhesive - adhere the components of the patch together and to the skin
 Membrane – controls release of the drug from reservoir and multi-layer patches
 Backing - protects the patch from the outer environment
56

57. Types of TD patch:-
 Single layer drug in adhesive
 Multi -layer drug in adhesive
- immediate drug release layer
 Vapour patch
- for releasing of essential oils in decongestion
 Reservoir system
- liquid drug solution containing reservoir is embedded between an impervious
backing layer and a rate controlling semi permeable membrane
 Matrix system
- similar to that of the reservoir, but the drug is instead provided as a semisolid
formulation, and there is no membrane layer
57

58. Evaluation
of patch
21-day
cumulative
irritancy patch
test
Kligman
“maximization”
test
Draize-shelanski
repeat-insult
patch test

59. Advanced designs for TDDS:-
 Jet injectors:-
Jet injectors are hand-held devices that deliver a high-pressure liquid stream
through a small nozzle orifice
59

60. Iontophoresis:-
• Technique involving the transport of ionic or charged molecules into tissue
by the passage of direct or periodic electric current through an electrolyte
solution
• Limitations: Hair follicle damage is possible
• E.g. Pilocarpine Iontophoresis in sweat test for Cystic Fibrosis
60

61. Ultrasound (Phonophoresis / Sonophoresis):-
Skin is made permeable under the influence of ultrasonic waves
• Sonophoresis: involves the usage of the low frequency ultrasound waves. The
ultrasonic energy disturbs the lipid packing in stratum corneum by cavitation
• Phonophoresis: movement of drugs through living intact skin and into soft
tissues under the ultrasound perturbation. The technique involves placing an
ultrasound-coupling agent on the skin over the area to be treated and massaging
the area with an ultrasound source
61

62. Microfabricated Microneedles Technology:-
This technology employs micron-sized needles (10 to 200 μm in height and 10 to
50 μm in width) made of silicon. These microneedles after insertion into the skin
create conduits for transfer of drug through the stratum corneum. The drug after
crossing stratum corneum diffuses rapidly through deeper tissues and are taken up
by capillaries for systemic action
62

63. Penetration or Permeation Enhancers:-
 Chemical penetration enhancers:
• reversibly reduce the barrier resistance of the stratum corneum without
damaging the skin cells
• E.g. Dimethyl sulphoxides, long chain alkanes, pyrrolidone, urea, alcohol,
surfactants
 Skin ablation:
• doubling of the TEWL (Trans Epidermal Water Loss) using surgical tapes
• Microsecond thermal ablation- a promising mechanism to increase
permeability of the skin's outer barrier layer of stratum corneum while
sparing deeper living tissues to aid skin permeation
63

64. Novel Topical Drug Delivery System:
Aerosol Foams:-
• becoming increasingly popular
topical formulation
• vehicle base is of liquid or semi-solid,
sharing the same physicochemical
characteristics of conventional
vehicles
• maintains desirable properties such as
moisturizing/ fast-drying effects,
higher drug bioavailability
• aerosol is dispensed through a gas-pressurized
can
• In acne, foams may be preferred for
application on large hairy surfaces or
on the face as they are easy to apply
64

65. Liposomes:-
• frequently used as vehicle for controlled and optimized delivery to skin layers
• spherical phospholipid vesicles whose membrane consists of amphiphilic lipid
(hydrophilic on outer side and lipophilic on the inner side) that enclose an
aqueous core
• thus they may encapsulate hydrophilic substances in their aqueous core and
lipophilic substances in their lipid bilayer.
• unique dual release capability enables the delivery of two types of substances
simultaneously once they are applied on the skin, which may enhance the
desired therapeutic benefit
65

66. 66

67. Niosomes:-
 Niosomes are microscopic lamellar structures composed of non-ionic surfactants
and cholesterol
Carrier + surfactant = Proniosomes
Proniosomes + water = Niosomes
 Niosomes and liposomes have similar application in drug delivery but chemically
differ in structure units. Niosomes constitute of non-ionic surfactant whereas
liposomes comprise of phospholipids
 Mixture of acorbyl palmitate, cholesterol and highly charged lipid diacetyl
phosphate leads to the construction of vesicles named aspasomes. Aspasomes
are first hydrated with water/aqueous solution and then sonicated to attain the
niosomes
67

68. Nano-emulsions:-
• class of emulsions - water-in-oil or oil-in-water, dispersion of very
small- sized droplets (5-200 nm) when mixed
• require unique thermodynamic conditions, specialized manufacturing
processes, and specific surfactants that can stabilize the nano droplets
• suitable for the transport of lipophilic compounds into the skin- ideal
vehicle for use in acne to increase the penetration of the active
compounds inside the lipophilic environment
• in addition, they do not clog the pores & can produce additional
therapeutic effects, such as increased skin hydration and
viscoelasticity
68

69. Polymers:-
• large molecules consisting of repeating structural units or monomers connected
by covalent chemical bonds
• in pharmaceutical industry, there are new acrylic-acid polymers that turn into a
gel in the presence of water by trapping water into microcells. Inside these
aqueous microcells, hydrophilic compounds can remain in a solution, whereas
hydrophobic compounds may be dispersed in suspension. The result is a stable
gel like formulation that is easy to use and releases the active compound(s) once
they are applied on the skin.
• moreover, these polymer-based gels can be mixed with other excipients, such as
moisturizers and emollients, to provide additional clinical benefits.
• recently introduced anti-acne formulations that combine clindamycin 1% with
benzoyl peroxide 5% utilize this novel polymer-based gel technology that
exhibits efficacy and excellent tolerability.
69

70. Microsponges:-
• biologically inert particles
• made of synthetic polymers with the capacity to store a volume of an active
agent up to their own weight
• the particles serve to protect the entrapped active compound from physical and
environmental degradation
• more frequently manufactured as gels
• once applied on the skin, they slowly release the active agent(s)
70

71. Emulsifier-free Formulations:-
• growing area of development for dermatologic and cosmetic products
• most skin care products are emulsions - mixture of 2 or more materials
that are not miscible with each other, thus requiring addition of
surfactants (emulsifiers) that stabilize the formulation to guarantee an
adequate shelf life
• once these surfactant agents are applied on the skin, they tend to
emulsify and remove the natural lipids of the epidermis
• consequently, the pharmaceutical industry has been developing
surfactant-free emulsions as alternatives by using stabilizers, in order to
yield sufficiently stable products with a cosmetically pleasant appearance
71

72. Fullerenes:-
 molecules composed entirely of carbon that resemble a hollow sphere
 Rouse, et al., showed that once fullerenes come into contact with the skin, they
migrate through the skin intercellularly, as opposed to moving through cells
 therefore, a fullerene could be used to “trap” active compounds and then release
them into the epidermis once they are applied on the skin
 moreover, fullerenes, themselves, are thought to be potentially potent
antioxidants
 they are well tolerated & hold substantial promise in dermatologic and cosmetic
applications.
Rouse JG, Yang J, Ryman-Rasmussen JP, et al. Effects of mechanical flexion on the penetration of fullerene amino acid- derivatized
peptide nanoparticles through skin. Nano Lett 7(1):155-60 (2007 Jan)
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73. 73
Conclusion:-
• Topical preparations are used for the localized effects at the site of their
application by virtue of drug penetration into the underlying layers of skin
or mucous membranes
• The main advantage of topical delivery system is to bypass first pass
metabolism
• Avoidance of the risks and inconveniences of parenteral therapy and of the
varied conditions of absorption, like pH changes, presence of enzymes,
gastric emptying time are other advantage of topical preparations
• Iontophoresis, Electroporation, Sonophoresis, Phonophoresis, Vesicular
concept and Microfabricated microneedles technology are some advanced
technique which are being used to increase delivery through skin
• Semi-solid formulation in all their diversity dominate the system for topical
delivery, but foams, spray, medicated powders, solution, and medicated
adhesive patches are also widely used