Drugs acting on Skin and Mucous membrane

1. Drugs Acting on Skin &
Mucous Membrane
Dr. Lokendra Sharma
Senior Professor SMS Medical
College Jaipur

2. Facts About Skin
The largest organ of the body
Very important protective layer of the body
Also important for:
 Thermoregulation
Immunity
Biochemical synthesis
 Sensory functions

3. Structure & function of skin
Skin has two layers:
- Epidermis
- Dermis: beneath dermis
there is fatty tissue
- Epidermis, the outer layer
- Keratin → present in all the
layers of epidermis
- Abnormal keratin production →
psoriasis & icthyotic disorders

4. Structure & Functions of Skin
Superficial keratin layer → stratum corneum
Main function of epidermis → to form
stratum corneum
Stratum corneum (horny layer) is important
→ reducing water loss and prevention of
absorption of noxious substances
 Stratum corneum main barrier for absorption of drugs by
topical route Structure & function of skin

5. Modes of treatment of skin disorders
Topical
Systemic
 Intralesional
 Controlled ultraviolet (UV)
radiations
 UV radiations are toxic &
can cause sunburn even
cancer of skin

6. Factors Governing Rate Of Absorption
Of Topical Drugs
Thickness of skin
Conc. of drug in vehicle
Degree of hydration
 Absorption varies in normal skin, damaged skin &
exfoliation of skin
 Transdermal patches → Clonidine (HT), hyoscine
 (motion sickness) & nitroglycerine (angina pectoris)

8. Vehicles
 Are inert substances
 They also contain some preservatives
 Monophasic e.g. powders, greases & liquids
 Biphasic e.g. pastes, creams and shake lotions
 Triphasic e.g. cream pastes & cooling pastes
 Vehicle should be non-irritant & cosmetically
suitable
 First pass metabolism in epidermis & dermis also
affects the
 systemic effect

9. Vehicles
Powders
• Because of soothing & cooling effect
→ reduce friction by absorbing
moisture
• Adhere poorly to skin → reduces their
usefulness
Greases
• Petroleum jelly & polyethylene glycol
are protective
Ointment
• Maintain the hydration of stratum
corneum Vehicles

10. Vehicles
Liquids
 Clean and keep the lesion/skin cool
 High water content of lotions are also
called wet dressings e.g. KMNO4,
normal saline
Gel & jellies
 They are semisolid due to addition of
polymers despite containing liquid phase
Creams
 Oil in water (o/w) type eg.
Vanishing/aqueous cream
 Water in oil (w/o) type eg. Cold cream

11. Vehicles
Shake lotions (lotion +powder)
- Cause cooling of skin due to evaporation of
water
Newer Vehicles
- Collodions
- Liposomes
- Microparticle
- Transferosomes

12. Skin Preparations
Topical preparations are
used for local effect
However, TD patches are
used for systemic effects
 Adsorbants and protectives
Bind to noxious and irritant
substances on their surface –
adsorbant action
 Dusting powder, Zinc oxide,
Calamine, Talc, Boric acid, polyvinyl
polymer, Sucralfate

13. Skin Preparations
Astringents
Tannic Acid
- Present in tea, catechu, nutmeg etc. → denaturation of
proteins & forms coating
- Can be used for bleeding gums (with glycerin) &
bleeding piles (as suppository)
Ethanol & methanol
- Cause precipitation of proteins and are applied locally
for prevention of bed sores and after shave lotion

14. Skin Preparations
Escharotics (chemical cauterizers)
- Cause tissue destruction, sloughing &
precipitation of proteins
- Used to remove warts, moles, papilloma etc.
Phenol, Trichloroacetic acid, silver nitrate,
podophyllum

15. Skin Preparations
Demulcents:
- Glycerine & propylene glycol
- Produce soothing effect on denuded mucosa or
inflammed skin
- Protect the mucous membrane and skin
Emollients:
-wax – hard & soft, paraffin, olive oil etc.
-Produce soothing effect & hydrate the skin
-Useful for dry scaly

16. Skin Preparations
Irritants and counterirritants
- Nicotinate, salicylate, menthol, camphor, capsaicin
- Produce local inflammation, tingling, numbness,
cooling or feeling of warmth, hyperaesthesia and
vasodilatation
Counterirritants
-Produce local irritation and relieve pain &
inflammation
arising from deeper structures
-Used for headache, myalgia, neuralgia, joint pain etc

17. Chemotherapeutic Agents
Antibacterial Agents
- Common bacterial infections affecting skin: -
Furuncle, boil, folluculitis, pyoderma, impetigo,
cellulitis etc
Antifungal Agents (Benzoic acid)
- Common fungal infections- ring worm, oral thrush,
dandruff, athlete’s foot
Antiviral Agents
Herpes simplex, herpes zoster

18. UV rays and effects on the skin
Three types of UV rays:
UVA (Long wave):
UVB (medium wave):
UVC (short wave):
Protection against UV rays:
Avoid exposure to UV
rays
Use sunscreens

19. Sunscreens
Required to prevent sun burn, aging and skin
cancer
Classification of sunscreens based on:
1. Physical Action:
2. Chemical structure:
3. Effectiveness against radiation

20. Photosensitivity due to drugs
Systemic use:
- BZDs, thiazides, hydralazine, sulfonamides,
sulfonylurea, NSAIDs, tetracycline, chloramiphenic
Topical use:
PABA as sunscreen, musk ambrette (used in perfumes),
6 methyl coumarin (after shave lotion)
Phototoxicity causes severe sun burn
Photoallergy: reaction persists years after the drug
withdrawal

21. Keratolytic Agents
Used to remove warts and corns,
calluses & verrucae
Mild keratolytic
Strong keratolytic
Some other keratolytic agents:
Lactic, Glycolic & salicylic acid

24. Drugs Based On Disease/Symptoms
Pruritus
•Itching – symptom of many skin
diseases
• Treatment depends upon cause of
pruritus
Drugs
Systemic
Antihistaminics
Glucocorticoids
Topical - Corticosteroids e.g. in eczema
- Emollient cream, menthol,camphor,
phenol, calamine, tar & others

30. Acne Vulgaris
A common skin disorder seen in adolescents
(boys & girls)
Is due infection of pilosebaceous unit by the
bacteria Propionibacium acnes
Changes in acne
1. Plugging of hair follicle
2. Accumulation of sebum
3. Growth of Propionibacium acnes
4. Inflammation

31. Acne Vulgaris treatment
The treatment aims at:-
1. Correction of follicular abnormality
2. Reducing sebum production
3. Controlling infection
4. Reducing Inflammation

32. Acne Vulgaris treatment
Topical Agents
Systemic Agents
Antibacterial Agents
Hormones & Hormones
antagonists

34. Thank You