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Topical drug delivery

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Viable epidermis/dermis -- antiinflammation, anesthetics, antihistamine, antipruritic ... Hapten contacts skin epidermis. Hapten complexes with protein ... – PowerPoint PPT presentation

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Title: Topical drug delivery


1
Topical drug delivery
  • Skin anatomy
  • Functions of skin
  • Five main target regions in dermatological
    therapy
  • Sunscreen on skin surface
  • Acne to target hair follicles and pilosebaceous
    unites
  • Delivery of macromolecules via the hair
    follicles
  • Contact dermatitis and viable epidermis and
    dermis

2
Skin anatomy
  • Epidermis
  • --0.8 to 0.006 mm.
  • --stratum corneum 10 mm when dry, horny layer
    (10-20 moisture)
  • Dermis
  • --3-5 mm
  • --a matrix of connective tissues woven
    fibrous proteins
  • --Nerves, blood vessels (lt 0.2 mm deep),
    lymphatics
  • Subcutaneous tissue
  • --mechanical cushion, thermal barrier, energy
    storage
  • Appendages
  • --Sweat glands
  • --hair follicles
  • --Sebaceous glands
  • --Nails

3
Functions of skin
  • Mechanical function
  • -- mainly from the dermis and s.c. tissues
  • -- epidermis (minor)
  • Protective function
  • -- Microbiological barrier
  • -- Chemical barrier
  • -- Radiation barrier
  • -- Heat barrier/temperature regulation
  • -- Immune response

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5
Stages on percutaneous absorption from a
suspension ointment
6
Five main target regions in dermatology
  • Surface treatment
  • -- Camouflage, protective layer, insect
    repellent, antimicrobial/antifungal, Sunscreen
  • Stratum corneum
  • -- Emollient, keratosis
  • Skin appendage
  • -- Acne, antibiotics, depilatory,
    antiperspirant, vaccine
  • Viable epidermis/dermis
  • -- antiinflammation, anesthetics,
    antihistamine, antipruritic
  • Systemic treatment
  • -- transdermal

7
Sunlight, sunscreen, suntan
UVA suntan, and PUVA treatment of psoriasis
(psoralen UVA), photosensitivity, photoaging,
photodermatoses, and augment cancerous effects of
UVB. UVB Vitamin D synthesis Cause sunburn,
skin cancers UVC
8
UV spectrum
Factors affecting exposure to UVR Time of the
day, Altitude, environmental factors, and
predisposed factors.
9
Suntan and sunburn
  • Sun tanning a result of two processes
  • -- Oxidation of melanin/immediate darkening
  • -- Stimulation of melanocytes/delayed
    tanning
  • Tanning increases tolerance to
    additional sun light.
  • Sunburn a superficial burn involving the
    epidermis.
  • -- Normal sequence
  • -- Erythema, 20-30 min, oxidation of melanin
    and dilation of dermal venules
  • -- True sunburn erythema, 2-8 h
  • -- Localized edema and pain, 14-20 h, last
    1-3 days
  • Other reactions to UVR
  • -- actinic keratosis, squamous cell
    carcinoma, basal cell carcinoma, melanoma.

10
Sunscreen agents
  • SPF Minimal, 2-12 Moderate, 12-30
  • high, gt 30
  • SPF is the minimal erythema dose (MED) of
    protected skin over the MED of unprotected skin.
    MED is the amount of solar radiation needed to
    produce minimal skin redness.
  • Types of sunscreens
  • Physical sun blockers
  • Titanium dioxide, Zinc oxide, Red
    petrolatum
  • Chemical sun absorbers
  • (1) PABA
  • (2) Cinnamates
  • (3) Salicylates
  • (4) Benzophenones
  • (5) Avobenzone (Parsol 1789)

Physical blockers are opaque formulations that
reflect and scatter up to 99 of light in both VR
and vis ranges. Less cosmetically
acceptable/greasy.
Sunscreens just need to bind and remain on the
skin for sufficient time.
11
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12
Dihydroxyacetone (DHA)
Coppertone
Erythrulose
DHA is a chemical agent that darkens the skin by
reacting with keratin in the stratum corneum to
produce artificial suntan. It provides no
protection against UV rays, and may not be
natural looking. The Eryhtrulose is also in some
products. It can be in lotion, gel, spray,
solution, etc.
13
Acne
  • Acne vulgaris is a disorder of the pilosebaceous
    units.
  • A plug of the pilosebaceous duct and follicle
    opening.
  • Drugs have to get into the hair follicles and
    pilosabaceous units

http//www.skincarephysicians.com/acnenet/acne.htm
l
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15
Etiology
  • Increased sebum production
  • Androgens regulate sebum production.
    Testosterone converted to DHT, which induces
    sebaceous glands to increase in size and
    activity, resulting in increased amount of sebum.
  • Abnormal clumping of epithelial horny cells in
    the pilosebaceous unit
  • Horny cells usually sloughed off from
    epithelial lining of the pilosebaceous duct.
  • Retention hyperkeratosis (increased
    adherence and production of follicular epithelial
    cells)
  • Presence of Propionibacterium acnes
  • P. acnes lipases break triglyceride to fatty
    acids, which are irritating, cause comedones, and
    result in inflammation.

16
Assessment of acne severity
Self treatment with OTC agents is only OK for
grade I.
17
Approaches for treatment
  • Increased sebum production
  • Testosterone converted to DHT, which induces
    sebaceous glands size and activity.
  • Abnormal clumping of epithelial horny cells in
    the pilosebaceous unit
  • Retenion hyperkeratosis
  • Presence of Propionibacterium acnes
  • P. acnes lipases break triglyceride to fatty
    acids, which are irritating, causing comedones.

Decreasing the amount of sebum produced Unblocki
ng the sebaceous ducts Kill the bacteria
18
OTC acne product
  • Benzoyl peroxide
  • -- 2.5 to 10
  • -- Most effective OTC
  • -- Kill P. acnes and irritant to increase
    epithelial cell turnover rate.
  • -- gel, cream, or lotion
  • Salicylic acid
  • -- 0.5-2, irritant keratolytic agent,
    lotion, creams
  • Sulfur, 3-8 combined with resorcinol 2, or
    resorcinol monacetate 3.
  • keratolytic and antibacteria, color/odor
  • Resorcinol
  • -- 1-4, keratolytic when combined with sulfur

19
Prescription
  • Tretinoin (retin-A)
  • increase the turnover rate of nonadhering horny
    cells in follicles.
  • Cream, gel, topical solution
  • More effective agent for acne
  • Increase hair growth
  • Others Adapalene (Differin), Tazarotene gel and
    cream (Tazorac), antibiotics (tetracyline,
    erythromycin, clindamycin, etc)
  • Isotretinoin (Accutane)
  • For severe racalcitrant nodulocytic acnes
  • Decrease sebum and keratinization
  • Reduce population of P. acnes
  • Birth defect

20
Tretinoin is very effective
21
Hair follicular cycle
Human Normally up to 90 of the hair follicles
are in anagen phase while, 1014 are in telogen
and 12 in catagen. Rodent hair follicles are
synchronized in the first two cycles.
22
Hair follicles as a route for drug/vaccine
delivery
23
Macromolecules access skin via hair follicles
24
Contact dermatitisInflammation of the skin
  • Irritant contact dermatitis
  • Caused by direct contact with the irritant
  • Absolute primary irritants acids, alkalis,
    industrial chemicals,
  • Relative primary irritants soaps,
    detergent, benzoyl peroxide, etc)
  • Allergic contact dermatitis
  • The result of direct contact with a contact
    allergen, such as poison ivy and nickel.
    Allergic contact dermatitis is considered a
    T-cell mediated delayed-response immune reaction,
    because elicitation of an allergic reaction
    typically takes 48 to 72 hours to occur after
    reexposure to the same allergen.

25
Allergic contact dermatitis
  • Hapten contacts skin epidermis
  • Hapten complexes with protein
  • Hapten-protein enters lymphatic systems
  • Generation of specific Th1 CD4 and CD8 T cells.
  • Re-exposure
  • Dermatitis responses
  • Urushiol from poison ivy, poison oak, and sumac.

Hapten small molecules that are only antigenic
when combined with a carrier protein.
http//www.poison-ivy.org/
26
Treatments
  • Severe eruptions systemic corticosteriods
  • Less severe eruptions
  • Relieve itching
  • Local anesthetics (benzocaine)
  • Antihistamines (oral or topical, mainly
    sedative effect)
  • Topical hydrocortisone
  • Treatment
  • Topical hydrocortisone.

27
Topical corticosteriod preparations
28
Some brand names of hydrocortisone
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