AIM Step 10
Student Memory Support
Topic 19 — Pharmacotherapy of Inflammatory, Pruritic, Pigmentary and Appendageal Skin Disorders
3rd Year MBBS • MSK • High-yield memory reinforcement and last-minute revision
1. High-Yield Flashcards
Tap each question to reveal the answer.
Which acne drug is most useful for normalizing abnormal follicular keratinization?
Topical retinoids such as tretinoin, adapalene and tazarotene.
Why is benzoyl peroxide useful with topical antibiotics in acne?
It provides antibacterial activity and helps reduce development of bacterial resistance.
Which oral acne drug markedly reduces sebum but has major teratogenic risk?
Isotretinoin.
What is the main immune target of imiquimod?
Toll-like receptor 7, causing increased local cytokine-mediated immunity.
How does topical tacrolimus reduce inflammation?
It inhibits calcineurin, reducing IL-2 production and T-cell activation.
Which ectoparasiticide is important for both scabies and pediculosis?
Permethrin.
What is the mechanism of permethrin against mites and lice?
It alters parasite voltage-gated sodium channel function, causing prolonged depolarization and paralysis.
Which depigmenting agent may cause exogenous ochronosis with prolonged misuse?
Hydroquinone.
Which drug can produce permanent depigmentation by damaging melanocytes?
Monobenzone.
Which vitamin D analogue is used topically in plaque psoriasis?
Calcipotriol.
Which psoriasis drug is strongly associated with nephrotoxicity and hypertension?
Cyclosporine.
Which adverse effects are characteristic of prolonged potent topical corticosteroid use?
Skin atrophy, striae and telangiectasia.
Which keratolytic reduces cohesion between cells of the stratum corneum?
Salicylic acid.
Which drug promotes hair growth in androgenetic alopecia without reducing DHT formation?
Minoxidil.
Which topical antineoplastic drug inhibits thymidylate synthase?
5-Fluorouracil.
2. Mnemonics
Mnemonic Title: Major Acne Targets
Mnemonic Word: S-F-B-I
Meaning: Sebum – Follicular obstruction – Bacteria – Inflammation.
Mnemonic Word: S-F-B-I
Meaning: Sebum – Follicular obstruction – Bacteria – Inflammation.
Mnemonic Title: Potent Topical Steroid Skin Toxicity
Mnemonic Word: AST
Meaning: Atrophy – Striae – Telangiectasia.
Mnemonic Word: AST
Meaning: Atrophy – Striae – Telangiectasia.
Mnemonic Title: Hair-Modifying Drugs
Mnemonic Word: M-F-E
Meaning: Minoxidil promotes growth – Finasteride reduces DHT – Eflornithine slows unwanted growth.
Mnemonic Word: M-F-E
Meaning: Minoxidil promotes growth – Finasteride reduces DHT – Eflornithine slows unwanted growth.
3. Memory Tables
Imiquimod vs Tacrolimus
| Feature | Imiquimod | Tacrolimus |
|---|---|---|
| Target | TLR7 | Calcineurin |
| Immune effect | Stimulates local immunity | Suppresses T-cell activity |
| Typical use | Warts, actinic keratoses | Atopic dermatitis |
| Key adverse effect | Local inflammation | Burning or stinging |
Permethrin vs Ivermectin
| Feature | Permethrin | Ivermectin |
|---|---|---|
| Main target | Parasite sodium channels | Ligand-gated chloride channels |
| Result | Prolonged depolarization and paralysis | Hyperpolarization and paralysis |
| Use | Scabies and pediculosis | Scabies and pediculosis |
4. Rapid Revision Points — Last-Minute Revision
Must Remember:
- Topical retinoids reduce comedone formation by normalizing follicular keratinization.
- Benzoyl peroxide has antibacterial activity without the same resistance problem as conventional antibiotics.
- Minocycline may produce vestibular adverse effects.
- Tacrolimus is useful as a steroid-sparing agent on sensitive skin sites.
- Permethrin may cause local burning, stinging or erythema.
- Psoralens increase UVA sensitivity and can cause phototoxic injury.
- Calcipotriol reduces keratinocyte proliferation and promotes differentiation.
- Methotrexate may cause hepatotoxicity and bone marrow suppression.
- Cyclosporine toxicity classically includes nephrotoxicity and hypertension.
- Occlusion increases absorption and toxicity of topical corticosteroids.
- Finasteride inhibits 5-alpha-reductase and reduces DHT formation.
5. Clinical Memory Hooks
Severe acne with marked mucocutaneous dryness → think systemic isotretinoin and remember teratogenicity.
Facial atopic dermatitis needing a steroid-sparing agent → tacrolimus suppresses T-cell activation without characteristic skin atrophy.
Nocturnal pruritus in several close contacts → treat scabies pharmacologically and address contacts and contaminated bedding.
Blue-black pigmentation after prolonged skin-lightening treatment → consider hydroquinone-associated exogenous ochronosis.
Thick scaly plaque limiting topical drug penetration → a keratolytic such as salicylic acid can reduce excess stratum corneum.
6. Starred High-Yield Exam Points
- ⭐ Isotretinoin is highly effective in severe acne but is strongly teratogenic.
- ⭐ Imiquimod activates TLR7; tacrolimus inhibits calcineurin.
- ⭐ Permethrin acts mainly on parasite sodium channels and is used in both scabies and pediculosis.
- ⭐ Hydroquinone misuse may produce exogenous ochronosis.
- ⭐ Cyclosporine in psoriasis is linked to nephrotoxicity and hypertension.
- ⭐ Potent topical corticosteroids can cause skin atrophy, striae and telangiectasia.
- ⭐ 5-Fluorouracil inhibits thymidylate synthase and damages rapidly proliferating abnormal epidermal cells.