Dermatological Pharmacology — MCQs

Dermatological Pharmacology Indian Medical PG Practice Questions and MCQs

Question 41: Which of the following treatments would you recommend for this patient?

A. Topical antibiotic ointment
B. Apply hydrogen peroxide
C. Compression stockings (Correct Answer)
D. Oral antibiotics

Explanation: ***Compression stockings*** - **Compression therapy** is the cornerstone treatment for **chronic venous insufficiency** and **venous leg ulcers**, improving venous return and reducing edema. - **Graduated compression** (30-40 mmHg) promotes wound healing by reducing **venous hypertension** and improving tissue oxygenation. *Topical antibiotic ointment* - Not indicated for **uncomplicated venous ulcers** as they are typically not infected and may lead to **antibiotic resistance**. - Can cause **contact dermatitis** and **sensitization** in patients with chronic wounds and compromised skin barrier. *Apply hydrogen peroxide* - **Cytotoxic** to healthy tissue and **impairs wound healing** by damaging fibroblasts and granulation tissue. - Creates **oxygen radicals** that can delay epithelialization and worsen the wound bed environment. *Oral antibiotics* - Only indicated if there are **clinical signs of infection** (increased pain, purulent discharge, erythema, warmth). - **Inappropriate** for clean venous ulcers as it promotes **antibiotic resistance** without addressing the underlying **venous pathophysiology**.

Question 42: Steroids are contraindicated in all of the following conditions, EXCEPT:

A. Diabetes mellitus
B. Hypertension
C. Eczematous skin disease (Correct Answer)
D. Peptic ulcer disease

Explanation: **Explanation:** The correct answer is **Eczematous skin disease**. This question tests your knowledge of the systemic side effects of corticosteroids and their primary therapeutic indications in dermatology. **1. Why Eczematous skin disease is correct:** Corticosteroids are the **mainstay of treatment** for eczematous skin diseases (such as Atopic Dermatitis or Contact Dermatitis). They work through potent anti-inflammatory and immunosuppressive mechanisms, inhibiting cytokine production and stabilizing lysosomal membranes. In these conditions, steroids are an indication, not a contraindication. **2. Why the other options are wrong (Contraindications):** Systemic steroids are generally contraindicated (or must be used with extreme caution) in the following conditions due to their metabolic and physiological effects: * **Diabetes Mellitus:** Steroids promote gluconeogenesis and decrease peripheral glucose uptake, leading to hyperglycemia and worsening of glycemic control. * **Hypertension:** Steroids cause sodium and water retention (mineralocorticoid effect), which can exacerbate high blood pressure and lead to edema. * **Peptic Ulcer Disease:** Steroids inhibit prostaglandin synthesis in the gastric mucosa and can mask signs of perforation, increasing the risk of gastrointestinal bleeding and ulceration. **High-Yield Clinical Pearls for NEET-PG:** * **Absolute Contraindications:** Systemic fungal infections and hypersensitivity. * **Relative Contraindications:** Psychosis, Osteoporosis, and Active Tuberculosis (steroids can cause reactivation). * **Side Effect Profile:** Remember the mnemonic **CUSHINGOID** (Cataracts, Ulcers, Skin thinning/Striae, Hypertension/Hirsutism, Immunosuppression, Necrosis of femoral head, Glucose elevation, Osteoporosis, Impaired growth, Depression/Psychosis). * **Topical Steroid Side Effects:** Atrophy, telangiectasia, and tachyphylaxis (diminished response over time).

Question 43: Which drug is known to cause non-pigmenting fixed drug reactions?

A. Sulphonamides
B. Ampicillin
C. Pseudoephedrine (Correct Answer)
D. Carbamazepine

Explanation: **Explanation:** **Fixed Drug Eruption (FDE)** is a cutaneous drug reaction characterized by recurrent lesions appearing at the same anatomical site upon re-exposure to the offending agent. While most FDEs leave behind significant post-inflammatory hyperpigmentation (PIH), a specific subtype called **Non-pigmenting Fixed Drug Eruption (NPFDE)** resolves without any residual staining. **1. Why Pseudoephedrine is Correct:** Pseudoephedrine is the classic and most common cause of non-pigmenting FDE. Unlike typical FDEs where there is extensive basal cell degeneration and pigmentary incontinence (melanin dropping into the dermis), NPFDE involves more superficial dermal edema and less melanocyte damage. Clinically, it presents as large, symmetrical, erythematous, and edematous plaques that fade completely within weeks. **2. Analysis of Incorrect Options:** * **A. Sulphonamides:** These are the **most common cause of classic (pigmenting) FDE**. They typically leave behind a characteristic slate-gray or dusky brown hyperpigmentation. * **B. Ampicillin:** A common cause of morbilliform (exanthematous) rashes and can cause classic FDE, but it is not specifically associated with the non-pigmenting variant. * **C. Carbamazepine:** Frequently associated with severe cutaneous adverse reactions (SCARs) like Stevens-Johnson Syndrome (SJS) and DRESS syndrome, as well as classic FDE, but not NPFDE. **3. NEET-PG High-Yield Pearls:** * **Most common site for FDE:** Glans penis (overall, genitalia and lips are common). * **Most common drug for FDE (Overall):** Sulphonamides (specifically Cotrimoxazole). * **Other drugs causing NPFDE:** Piroxicam, Diflunisal, and Tadalafil (though Pseudoephedrine is the top examiner favorite). * **Pathology:** FDE is a **Type IV (Delayed) Hypersensitivity** reaction mediated by CD8+ T-cells.

Question 44: What is the treatment of choice for Sweet's syndrome?

A. Antibiotics
B. Antifungals
C. Corticosteroids (Correct Answer)
D. UV light

Explanation: **Explanation:** **Sweet’s Syndrome**, also known as **Acute Febrile Neutrophilic Dermatosis**, is a reactive skin condition characterized by the sudden onset of fever, leukocytosis, and painful, erythematous plaques or nodules. Histologically, it is defined by a dense infiltration of neutrophils in the upper dermis without evidence of vasculitis. **Why Corticosteroids are the Correct Choice:** Systemic **Corticosteroids** (e.g., Prednisolone) are the **gold standard and first-line treatment**. They work by rapidly suppressing the intense inflammatory response and neutrophilic infiltration. Patients typically show a dramatic response, with fever and skin lesions often improving within 48 to 72 hours. **Why Other Options are Incorrect:** * **Antibiotics:** Although the clinical presentation (fever, high WBC count, and red skin lesions) mimics a bacterial infection like cellulitis, Sweet’s syndrome is an inflammatory, non-infectious process. Antibiotics are ineffective. * **Antifungals:** There is no fungal etiology involved; this is an autoinflammatory reaction. * **UV Light:** Phototherapy is generally not used in the acute phase of Sweet’s syndrome and may even trigger lesions in some patients (pathergy-like phenomenon). **High-Yield Clinical Pearls for NEET-PG:** 1. **Associations:** Often associated with **Malignancy** (most commonly **AML**), infections (URTI), or inflammatory bowel disease (IBD). 2. **Pathergy Sign:** Like Pyoderma Gangrenosum and Behçet’s disease, Sweet’s syndrome can exhibit pathergy (skin lesions at sites of minor trauma). 3. **Histology:** Look for "Edema of the papillary dermis" and "Diffuse neutrophilic infiltrate" (Neutrophilic Dermatosis). 4. **Second-line agents:** If steroids are contraindicated, **Potassium Iodide**, **Colchicine**, or **Dapsone** can be used.

Question 45: What is the most common drug-induced skin reaction?

A. Maculopapular rash
B. Morbilliform rash (Correct Answer)
C. Fixed drug eruption
D. Photosensitivity reaction

Explanation: **Explanation:** **Morbilliform rash** (also known as exanthematous drug eruption) is the most common type of cutaneous adverse drug reaction, accounting for approximately **90-95%** of all drug-induced skin eruptions. 1. **Why Morbilliform Rash is Correct:** The term "morbilliform" refers to a measles-like appearance, characterized by symmetric, erythematous macules and papules that often coalesce. It typically develops **1 to 2 weeks** after starting a new medication (or within 1–3 days in previously sensitized individuals). It is a **Type IV (delayed) hypersensitivity reaction** mediated by T-cells. Common culprits include beta-lactams, sulfonamides, and anticonvulsants. 2. **Analysis of Incorrect Options:** * **Maculopapular rash:** While often used interchangeably with morbilliform in clinical practice, "morbilliform" is the more specific dermatological term preferred in exams to describe the classic drug-induced exanthem. * **Fixed Drug Eruption (FDE):** This is the **second most common** drug reaction. It is characterized by recurrent lesions (usually dusky red plaques) that appear in the exact same anatomical location every time the drug is ingested. * **Photosensitivity reaction:** These are common but significantly less frequent than exanthematous eruptions. They are categorized into phototoxic (more common) and photoallergic reactions. **High-Yield Clinical Pearls for NEET-PG:** * **Most common site:** Usually starts on the trunk and spreads symmetrically to the extremities. * **Mucosal involvement:** Typically absent in morbilliform rashes; if present, consider progression to more severe forms like Stevens-Johnson Syndrome (SJS). * **Management:** The most important step is the immediate withdrawal of the offending drug. * **Commonest drug causing FDE in India:** NSAIDs and Cotrimoxazole.

Question 46: Which drug is known to cause acanthosis nigricans?

A. Amphotericin-B
B. Ketoconazole
C. Nicotinic acid (Correct Answer)
D. Nalidixic acid

Explanation: **Explanation:** **Nicotinic acid (Niacin)** is a well-recognized pharmacological cause of **Acanthosis Nigricans (AN)**. The underlying mechanism involves the drug’s ability to induce insulin resistance and interfere with glucose metabolism. High doses of nicotinic acid can lead to an increase in insulin levels, which subsequently binds to **Insulin-like Growth Factor-1 (IGF-1) receptors** on keratinocytes and dermal fibroblasts. This stimulates the proliferation of these cells, resulting in the characteristic velvety, hyperpigmented plaques seen in AN. **Analysis of Incorrect Options:** * **Amphotericin-B:** This antifungal is primarily known for its systemic toxicities, such as nephrotoxicity, infusion-related reactions (chills/rigors), and hypokalemia. It does not cause acanthosis nigricans. * **Ketoconazole:** An imidazole antifungal that can cause hepatotoxicity and gynecomastia (due to inhibition of testosterone synthesis). While it has various side effects, AN is not one of them. * **Nalidixic acid:** A quinolone antibiotic known for causing **pseudoporphyria** and cutaneous photosensitivity, but it is not associated with insulin-mediated skin changes. **Clinical Pearls for NEET-PG:** * **Drug-induced AN:** Other common culprits include **systemic glucocorticoids**, oral contraceptives, protease inhibitors, and growth hormone therapy. * **Malignant AN:** If AN appears suddenly, is very extensive, or involves the palms/soles (Tripe palms), it is often a paraneoplastic sign of internal malignancy, most commonly **Gastric Adenocarcinoma**. * **Commonest Association:** In clinical practice, AN is most frequently associated with **obesity and Type 2 Diabetes Mellitus**.

Question 47: Chloroquine is used in the treatment of which of the following dermatological conditions?

A. Discoid Lupus Erythematosus (DLE) (Correct Answer)
B. Pemphigus
C. Psoriasis
D. Nummular eczema

Explanation: **Explanation:** **Chloroquine** and its derivative, Hydroxychloroquine, are **Antimalarials** that serve as the first-line systemic therapy for various forms of Cutaneous Lupus Erythematosus, including **Discoid Lupus Erythematosus (DLE)**. **1. Why Option A is Correct:** The mechanism of action in DLE involves the inhibition of antigen presentation to T-cells, stabilization of lysosomal membranes, and interference with Toll-like receptor (TLR) signaling. These actions reduce the inflammatory response and protect the skin from UV-induced damage, which is a primary trigger for DLE lesions. **2. Why the Other Options are Incorrect:** * **B. Pemphigus:** This is an autoimmune blistering disease treated primarily with systemic corticosteroids and immunosuppressants (e.g., Azathioprine, Rituximab). Antimalarials have no proven efficacy here. * **C. Psoriasis:** Antimalarials are generally **contraindicated** in psoriasis as they can trigger or exacerbate the condition, potentially leading to exfoliative dermatitis or erythrodermic psoriasis. * **D. Nummular Eczema:** This is a form of dermatitis treated with topical steroids, emollients, and occasionally phototherapy. Antimalarials do not play a role in its management. **High-Yield Clinical Pearls for NEET-PG:** * **Ocular Toxicity:** The most significant side effect of long-term Chloroquine use is **"Bull’s eye maculopathy"** (retinopathy). Baseline and periodic ophthalmological screening are mandatory. * **Other Indications:** Antimalarials are also used in Polymorphous Light Eruption (PMLE), Porphyria Cutanea Tarda (PCT), and Sarcoidosis. * **Smoking:** It is a high-yield fact that smoking significantly **decreases the efficacy** of antimalarials in patients with DLE.

Question 48: Which of the following conditions is treated with systemic corticosteroids?

A. Systemic antifungal therapy
B. Systemic antiviral therapy
C. Systemic corticosteroids (Correct Answer)
D. Systemic antibiotics

Explanation: **Explanation:** The question focuses on the therapeutic application of **Systemic Corticosteroids** in dermatology. Systemic corticosteroids (e.g., Prednisolone, Dexamethasone) are the mainstay of treatment for **immunologically mediated, inflammatory, and bullous dermatoses**. They work by suppressing the immune response and inhibiting the release of pro-inflammatory cytokines. **Why Systemic Corticosteroids are correct:** In dermatology, systemic steroids are indicated for life-threatening or severe conditions where rapid immunosuppression is required. Key indications include: * **Immunobullous disorders:** Pemphigus vulgaris (Drug of choice) and Bullous pemphigoid. * **Connective Tissue Diseases:** Systemic Lupus Erythematosus (SLE) and Dermatomyositis. * **Severe Drug Reactions:** Stevens-Johnson Syndrome (SJS) / Toxic Epidermal Necrolysis (TEN) (though controversial, often used early) and DRESS syndrome. * **Acute Inflammatory states:** Severe Erythema Nodosum Leprosum (ENL) and Type 2 Lepra reactions. **Why other options are incorrect:** * **Systemic Antifungals:** Used for fungal infections like Tinea capitis, Onychomycosis, or deep mycoses. Steroids are generally contraindicated here as they can worsen infections (e.g., Tinea incognito). * **Systemic Antivirals:** Used for viral infections like Herpes Zoster or Varicella. * **Systemic Antibiotics:** Used for bacterial pyodermas (Impetigo, Cellulitis) or Acne vulgaris. **NEET-PG High-Yield Pearls:** * **Pulse Therapy:** High-dose intravenous Methylprednisolone (Dexamethasone-Cyclophosphamide Pulse or DCP) is a classic regimen used for Pemphigus Vulgaris to achieve rapid remission. * **Side Effects:** Long-term use leads to Cushingoid features, osteoporosis, avascular necrosis of the femoral head, and secondary infections. * **Contraindication:** Never use systemic steroids in **Psoriasis**, as withdrawal can precipitate life-threatening **Generalized Pustular Psoriasis**.

Question 49: Which of the following steroids is not used topically?

A. Hydrocortisone
B. Fluticasone
C. Triamcinolone
D. Prednisolone (Correct Answer)

Explanation: **Explanation:** The correct answer is **Prednisolone**. The fundamental pharmacological principle here is the distinction between **prodrugs** and **active metabolites**. Topical steroids must be biologically active upon application because the skin lacks the specific enzymes required to convert certain systemic prodrugs into their active forms. * **Prednisolone (Option D):** This is primarily an oral or parenteral steroid. While its derivative, *Prednicarbate*, is used topically, pure Prednisolone is not used on the skin because it has poor lipophilicity and suboptimal topical potency compared to halogenated steroids. More importantly, its precursor, **Prednisone**, is a prodrug that requires hepatic conversion (via 11β-HSD1) to become active Prednisolone, making it ineffective for topical use. **Why other options are incorrect:** * **Hydrocortisone (Option A):** A low-potency (Group VII) topical steroid, often considered the "gold standard" for mild inflammatory conditions and use on delicate areas like the face. * **Fluticasone (Option B):** A potent (Group III/IV) fluorinated corticosteroid commonly used topically for eczema and psoriasis due to its high affinity for glucocorticoid receptors. * **Triamcinolone (Option C):** A mid-to-high potency steroid available in various topical formulations (acetonide) and also used for intralesional injections (e.g., in keloids). **High-Yield NEET-PG Pearls:** 1. **Potency Classification:** Topical steroids are classified using the **Stoughton-Cornell classification** (Groups I to VII). Clobetasol propionate (0.05%) is the most potent (Group I). 2. **Side Effects:** Chronic use leads to skin atrophy, telangiectasia, and striae due to inhibition of fibroblast proliferation and collagen synthesis. 3. **Absorption:** Absorption is highest through the **mucous membranes > scrotum > eyelids > face**, and lowest through the palms and soles. 4. **Finger Tip Unit (FTU):** One FTU (0.5g) is the amount of cream squeezed from a 5mm nozzle from the tip of the finger to the first joint, enough to cover two adult palms.

Question 50: What is the most effective treatment for pruritus in uremia?

A. Ultraviolet light (Correct Answer)
B. Cholestyramine
C. Eskazine
D. Topical benzocaine

Explanation: **Explanation:** **Uremic pruritus** is a common and distressing complication of chronic kidney disease (CKD). While its exact pathogenesis is multifactorial—involving uremic toxins, systemic inflammation, and opioid receptor imbalances—**Ultraviolet (UV) light therapy**, specifically **Narrowband UVB (NB-UVB)**, is considered the most effective and first-line non-pharmacological treatment. * **Why Ultraviolet Light is Correct:** UV radiation (especially UVB) reduces the number of pro-inflammatory cytokines and mast cells in the skin. It also induces apoptosis of dermal mast cells and alters the cutaneous nerve endings, significantly reducing the itch sensation. It is highly effective in patients who do not respond to emollients or systemic antihistamines. **Analysis of Incorrect Options:** * **Cholestyramine (B):** This bile acid sequestrant is primarily used for pruritus associated with **cholestatic liver disease**. While it has been tried in uremia, its efficacy is inconsistent and inferior to phototherapy. * **Eskazine (C):** Also known as Trifluoperazine (an antipsychotic), it has no established role in treating uremic pruritus. * **Topical Benzocaine (D):** This is a local anesthetic. While it may provide transient numbing, it does not address the systemic cause of uremic itch and carries a high risk of **allergic contact dermatitis**. **High-Yield Clinical Pearls for NEET-PG:** 1. **First-line treatment:** Emollients and optimizing dialysis. 2. **Most effective/Gold standard:** NB-UVB phototherapy. 3. **Pharmacological options:** Gabapentin or Pregabalin (very effective, but requires dose adjustment for renal failure). 4. **Newer Drug:** **Difelikefalin** (a peripheral kappa-opioid receptor agonist) is now FDA-approved specifically for uremic pruritus. 5. **Key Association:** Uremic pruritus is often associated with secondary hyperparathyroidism and elevated calcium-phosphate product.

Practice by Chapter

Topical Corticosteroids

Practice Questions

Topical Antibiotics

Practice Questions

Topical Antifungals

Practice Questions

Topical Antivirals

Practice Questions

Topical Retinoids

Practice Questions

Systemic Retinoids

Practice Questions

Immunosuppressive Agents

Practice Questions

Antihistamines in Dermatology

Practice Questions

Biological Agents in Dermatology

Practice Questions

Dermatological Vehicles and Delivery Systems

Practice Questions

Phototherapeutic Agents

Practice Questions

Adverse Cutaneous Drug Reactions

Practice Questions

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