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Pharmacology second lecture

This pharmacology lecture covers topics such as immunomodulators, ectoparasiticides, agents affecting pigmentation, sunscreens, and acne preparations. Learn about the uses and mechanisms of these drugs.

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Pharmacology second lecture

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  1. Pharmacology second lecture • Extra notes were added to the slides and a sheet was not submitted due to the fact that doctor only mentioned minor details and mostly read from the slides without adding any notable information • Two parentheses () will indicate any extra information added to the slides

  2. Immunomodulators • Imiquimod: • For external genital and perianal warts. • Actinic keratosis on the face and scalp. • Primary basal cell carcinoma. • Stimulates peripheral mononuclear cells to release interferon- ά and to stimulate macrophages to produce interleukins-1,-6, and -8 and tumor necrosis factor-ά. • Tacrolimus • Pimecrolimus. • Useful for atopic dermatitis. • Inhibit T-lymphocyte activation and prevent release of inflammatory cytokines and mast cell mediators • ( Tacrolimus and Pimecrolimus are immune suppressant drugs that suppress rejection cases of organ transplant )

  3. Ectoparasiticides(parasites that affects the skin like lice and scabies) • Permethrin: • Toxic to Pediculushumanus(hair lice), Pthirus pubis(pubic lice), and Sarcoptesscabiei (scabies) • Pediculosis(Lice):cream applied for 10 minutes and then rinsed off with warm water. • Scabies: cream applied for the whole body for 8-14 hours. • (Parasite for scabies injures the skin and hides in stratum cornium where it lays its eggs, the eggs hatch to give larvae which start to crawl and this is the cause of itching sensation of scabies disease)

  4. Ectoparasiticides • Lindane (Hexachlorocyclohexane): • (Very toxic drug due its accumulation of in fatty tissues and we don’t use it unless the first drug applied is ineffective) • 10% absorbed and concentrated in fatty tissues. • Can cause neurotoxicity and hematoxicity • Crotamiton: drug that is used both as a scabicidal (for treating scabies) and as a general antipruritic • Sulfur (used to treat lice considered a strong medication) • Malathion (inhibits the acetylcholine esterase, Commonly used as an insecticide but at low concentration can be used for treatment of lice)

  5. Agents affecting Pigmentation • (When it comes to drugs affecting the pigmentation of the skin we have two different approaches the first is when we decrease the color and the second is when we restore the skin back to its normal color) • Hydroquinone: topical application skin whitening to reduce the color of skin (Temporary pigmentation) • Monobenzone Monobenzone may be toxic to melanocytes resulting in permanent depigmentation.

  6. Agents affecting Pigmentation • Mequinol • Topical hydroquinone and mequinol usually result in temporary lightening. • Reduce hyperpigmentation of skin by inhibiting the enzyme tyrosinase which will interfere with biosynthesis of melanin • (Monobenzoneresults in permanent depigmentation by irreversibly inhibiting the enzyme tyrosinase)

  7. Agents affecting Pigmentation • Trioxsalen. • Methoxsalen. • Are psoralens used for the repigmentation of depigmentedmacules of vitiligo(unwanted discoloration of the skin) • Must be photoactivated by long-wave-length ultraviolet light (320-400nm (UVa light)) to produce a beneficial effect( melanocytes produce melanin to recolor the skin) • They intercalate with DNA. • Can cause cataract and skin cancer( espically in light colored patients)

  8. Sunscreens and Sunshades • Sunscreens absorbUV light. • Examples are para amino benzoic acid (PABA) and its esters. • Sunshades are opaque Materials ( don’t absorb light) so instead these materials reflect light, like titanium dioxide. • Useful in polymorphous light eruption, lupus erythematosus, and drug –induced photosensitivity.

  9. Sunscreens and Sunshades • (Lupuserythematosus is a systematic (might affect the skin only) auto immune disease where antibodies disrupt cells of the body, this affects the skin cells and mucous membrane. This disease also has an affect on the kidneys and joints where it cause redness and ulceration)

  10. SPF • (The sun protection factor (SPF) of a given sunscreen is a measure of its effectiveness in absorbing erythrogenic ultraviolet light. It is determined by measuring the minimal erythema (abnormal redness of the skin) dose with and without the sunscreen in a group of normal people. The ratio of the minimal erythema dose with sunscreen to the minimal erythema dose without sunscreen is the SPF.) (the doctor said that we are not to be asked about SPF in the exam)

  11. Acne Preparations(Usually doctors start treating Acne by using tetracycline and topical creams) • Retinoic Acid and Derivatives: • Retinoic Acid ( Vitamin A) • Adapalene (sympathetic retinoic derivative) • Tazarotene. • Retinoic Acid and its derivatives are very strong drugs

  12. Acne Preparations • Retinoic Acid and Derivatives: • Retinoic Acid( Tretinoin): is the acid form of Vitamin A. Stabilizes lysosomes, increases RNA polymerase activity, increases PGE2, cAMP, and cGMP levels, and increases the incorporation of thymidine into DNA. • Decreases cohesion between epidermal cells and increases epidermal cell turnover. This will result in expulsion of open comedones (black heads) and the transformation of closed comedones into open ones. (requires TIME) • Also, promotes dermal collagen synthesis, new blood vessel formation, and thickeningof the epidermis, which helps diminish fine lines and wrinkles. • Can cause erythema and dryness. • Tumerogenic in animals

  13. Acne Preparations • Isotretinoin( Accutane): • Restricted for severe cystic acne resistant to standard treatment. (Isotretinoin affects liver enzymes) • Inhibits sebaceous gland size and function. • Given orally: 1–2 mg/kg, given in two divided doses daily for 4–5 months • Toxic: dryness, itching, headache, corneal opacities, pseudotumorcerebri (Idiopathic intracranial hypertension), inflammatory bowel disease, anorexia, alopecia, and muscle and joint pains. Also lipid abnormalities (increase triglycerides and HDL) • Teratogenicity

  14. Acne Preparations • Benzoyl Peroxide (Topical Drug): • Penetrates the stratum corneum or follicular openings and converted to benzoic acid within the epidermis and dermis. • Has antimicrobial activity against P. acnes and peeling and comedolytic effects. • Can be combined with erythromycin or clindamycin. • Can cause bleaching of hair or colored fabrics. • Azelaic Acid ( Topical Drug): • Has antimicrobial activity.

  15. Drugs for Psoriasis (an autoimmune disease or an allergic reaction) • Psoriasis is a chronic skin disease characterized by dry red patches covered with scales • Acitretin: • Related to isotretinoin. • Given orally. • Hepatotoxic and teratogenic. • Patients should not become pregnant for 3 years after stopping treatment, and also should not donate blood. • (Increases suicidal thoughts and tendency to commit suicide)

  16. Drugs for Psoriasis • Tazarotene (Topical Drug): • Topical. • Anti-inflammatory and antiproliferative actions. • Teratogenic. Also, can cause burning, stinging, peeling, erythema, and localized edema of skin. • Calcipotiene: • Synthetic vitamin D3 derivative

  17. Drugs for Psoriasis • Biologic Agents (The Doctor said that we should skip this slide and read it for our own knowledge): • Alefacept: • Immunosuppressive dimer fusion protein of CD2 linked to the Fc portion of human IgG1. • Efalizumab: • Recombinant humanized IgG1 monoclonal antibody. • Withdrawn :progressive multifocal leukoencephalopathy (PML), • Can cause thrombocytopenia. • Etanercept: • Dimeric fusion protein of TNF receptor linked to the Fc portion of human IgG1.

  18. Anti-inflammatory Agents • Topical Corticosteroids: • Hydrocortisone. • Prednisolone and Methylprednisolone. • Dexamethasone and Betamethasone. • Triamcinolone. • Fluocinonide.

  19. Anti-inflammatory Agents • Topical Cortcosteroids: • Dermatologic disorders very responsive to steroids: • Atopic dermatitis. • Seborrheic dermatitis. • Lichen simplex chronicus. • Pruritus ani. • Allergic contact dermatitis. • Eczematous dermatitis. • Psoriasis

  20. Anti-inflammatory Agents • Topical Cortcosteroids: • Adverse Effects: • Suppression of pituitary-adrenal axis. • Systemic effects. • Skin atrophy. • Erythema. • Pustules. • Acne. • Infections. • Hypopigmentation. • Allergic contact dermatitis.

  21. Anti-inflammatory Agents • Topical Cortcosteroids. • Tar compounds: • Mainly for psoriasis, dermatitis, and lichen simplex chronicus • Can cause irritant folliculitis(inflammation of follicles), phototoxicity, and allergic contact dermatitis.

  22. Keratolytic and Destructive Agents • (These agents dissolve the protein layer of the skin) • Salicylic acid: • Solubilizes cell surface proteins resulting in desquamation of keratotic debris. • Keratolytic in 3-6% concentration, but destructive in higher concentrations (higher concentrations are destructive because they penetrate deep in the skin). • Locally, can cause urticaria, anaphylactic and erythemamultiforme reactions, irritation, inflammation, and ulceration.

  23. Keratolytic and Destructive Agents • Propylene Glycole: • Usually used as a vehicle for organic compounds. • Used alone as a keratolytic agent in concentrations of 40%- 70%, with plastic occlusion, or in gel with 6% salicylic acid. • Minimally absorbed, oxidized in liver to lactic acid and pyruvic acid. • Develops an osmotic gradient through the stratum corneum, thereby increasing hydration of the outer layers of skin.

  24. Keratolytic and Destructive Agents • Urea: • Has a humectant activity, i.e. softening and moisturizing effect on the stratum corneum. • Increases water content as a result of its hygroscopic characteristics. • Decreases the unpleasant oily feel of dermatologic preparations. • When absorbed, it is excreted in urine.

  25. Keratolytic and Destructive Agents • Flurouracil: • Antimetabolite that resembles uracil and inhibits thymidylate synthetase, thus interferes with DNA and may be RNA synthesis. • Used in multiple actinic keratosis.

  26. Keratolytic and Destructive Agents • Nonsteroidal Anti-inflammatory Drugs: • 3% gel formulation diclofenac. • Aminolevulinic Acid: • Used in actinic keratosis. • After topical application(20%) and exposure to light, produces a cytotoxic superoxide and hydroxyl radicals

  27. Antipruritic Agents • Doxepine: • Potent H1 and H2 – receptor antagonist. • Can cause drowsiness and anticholinergic effects. • Pramoxine: • Is a topical local anesthetic agent.

  28. Trichogenic and Antitrichogenic Agents • Trichonegic means hair growth • Antitrichogenic means hair loss • Minoxidil (Rogaine): • Designed as an antihypertensive agent. • Effective in reversing the progressive miniaturization of terminal scalp hairs associated with androgenic alopecia. • Vertex balding is more responsive than frontal balding.

  29. Trichogenic and Antitrichogenic Agents • Minoxidil. • Finasteride (Propecia): • 5ά-reductase inhibitor which blocks the conversion of testosterone to dihydrotestosterne (dihydrotestosterone is responsible for secondary sex characteristics) • Oral tablets. • Can cause decreased libido, ejaculation disorders, and erectile dysfunction.

  30. Trichogenic and Antitrichogenic Agents • Minoxidil. • Finasteride. • Eflornithine: • Is an irreversible inhibitor of ornithine decarboxylase, therefore, inhibits polyamine synthesis. Polyamines are important in cell division and hair growth. • Effective in reducing facial hair growth in 30% of women when used for 6 months.

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