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Drugs acting on Skin and Mucous membrane

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Drugs acting on Skin and Mucous membrane

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Drugs acting on Skin and Mucous membrane

  1. 1. Drugs Acting on Skin & Mucous Membrane Dr. Lokendra Sharma Senior Professor SMS Medical College Jaipur
  2. 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. 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. 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. 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. 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)
  7. 7. 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
  8. 8. 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
  9. 9. 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
  10. 10. Vehicles Shake lotions (lotion +powder) - Cause cooling of skin due to evaporation of water Newer Vehicles - Collodions - Liposomes - Microparticle - Transferosomes
  11. 11. 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
  12. 12. 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
  13. 13. 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
  14. 14. 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
  15. 15. 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
  16. 16. 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
  17. 17. 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
  18. 18. 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
  19. 19. 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
  20. 20. Keratolytic Agents Used to remove warts and corns, calluses & verrucae Mild keratolytic Strong keratolytic Some other keratolytic agents: Lactic, Glycolic & salicylic acid
  21. 21. 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
  22. 22. 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
  23. 23. Acne Vulgaris treatment The treatment aims at:- 1. Correction of follicular abnormality 2. Reducing sebum production 3. Controlling infection 4. Reducing Inflammation
  24. 24. Acne Vulgaris treatment Topical Agents Systemic Agents Antibacterial Agents Hormones & Hormones antagonists
  25. 25. Thank You

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