Drugs Used in Skin Disorders — MCQs

Drugs Used in Skin Disorders Indian Medical PG Practice Questions and MCQs

Question 21: All of the following drugs are approved for the treatment of Psoriasis except?

A. Methotrexate
B. Alefacept
C. Infliximab
D. Tofacitinib (Correct Answer)

Explanation: **Explanation:** The correct answer is **Tofacitinib**. **1. Why Tofacitinib is the correct answer:** Tofacitinib is a **Janus Kinase (JAK) inhibitor** (specifically JAK1 and JAK3). While it is FDA-approved for Rheumatoid Arthritis, Psoriatic Arthritis, and Ulcerative Colitis, it is **not currently approved** for the treatment of Plaque Psoriasis. Clinical trials for its topical and oral use in psoriasis have been conducted, but safety concerns and regulatory hurdles have prevented its formal approval for skin-limited disease. **2. Analysis of Incorrect Options:** * **Methotrexate (Option A):** A folate antagonist that inhibits dihydrofolate reductase. It is a "gold standard" systemic therapy for moderate-to-severe psoriasis due to its anti-inflammatory and antiproliferative effects on keratinocytes. * **Alefacept (Option B):** A fusion protein that binds to CD2 on T-cells, inhibiting their activation. It was the first biologic approved for moderate-to-severe plaque psoriasis (though it has been voluntarily withdrawn from the US market by the manufacturer for business reasons, it remains a classic "approved" drug in pharmacology textbooks). * **Infliximab (Option C):** A chimeric monoclonal antibody against **TNF-α**. It is highly effective and approved for the treatment of chronic severe plaque psoriasis. **3. NEET-PG High-Yield Pearls:** * **First-line for mild psoriasis:** Topical Corticosteroids and Vitamin D3 analogues (Calcipotriol). * **Biologics for Psoriasis:** * **TNF-α inhibitors:** Infliximab, Etanercept, Adalimumab. * **IL-12/23 inhibitor:** Ustekinumab. * **IL-17 inhibitors:** Secukinumab, Ixekizumab. * **IL-23 inhibitors:** Guselkumab, Risankizumab. * **Apremilast:** An oral **PDE-4 inhibitor** approved for psoriasis; it increases intracellular cAMP. * **PUVA:** Psoralen + UVA radiation is a classic treatment for extensive disease.

Question 22: Which among the following is an antibiotic agent that penetrates burn eschar to reach the interface with the patient's underlying tissue?

A. Mafenide acetate (Correct Answer)
B. Neomycin
C. Silver nitrate
D. Silver sulfadiazine

Explanation: **Explanation:** The correct answer is **Mafenide acetate**. **1. Why Mafenide Acetate is Correct:** In severe burn injuries, the formation of **eschar** (dead, necrotic tissue) creates a barrier that most topical antibiotics cannot penetrate. Mafenide acetate is a sulfonamide derivative unique for its ability to **diffuse rapidly through thick burn eschar**. This allows it to reach the interface between the eschar and the underlying viable tissue, effectively preventing and treating bacterial colonization (especially *Pseudomonas aeruginosa*) in deep or infected burns. **2. Why Other Options are Incorrect:** * **Silver Sulfadiazine:** While it is the most commonly used topical agent for burns due to its broad-spectrum activity and painless application, it **does not penetrate eschar** effectively. It acts primarily on the surface. * **Silver Nitrate:** This agent is used as a 0.5% solution. It has poor penetrative power, can cause electrolyte imbalances (hyponatremia, hypochloremia), and stains the skin/dressings black. * **Neomycin:** This is an aminoglycoside used for superficial skin infections but is not a standard treatment for deep burn eschar due to its lack of penetration and potential for nephrotoxicity/ototoxicity if absorbed systemically. **3. High-Yield Clinical Pearls for NEET-PG:** * **Adverse Effect:** Mafenide acetate is a potent inhibitor of **carbonic anhydrase**. Its use over large surface areas can lead to **metabolic acidosis** and compensatory hyperventilation. * **Application Pain:** Unlike silver sulfadiazine, mafenide acetate application is often painful (burning sensation), which may limit its use in conscious patients. * **Spectrum:** It is highly effective against *Pseudomonas* and *Clostridia*. * **Silver Sulfadiazine Side Effect:** Watch for **transient leukopenia** (neutropenia) during the first few days of therapy.

Question 23: Which of the following is NOT true regarding silver sulfadiazine used in burns?

A. Diffuses well through eschar (Correct Answer)
B. Causes wound maceration
C. Causes hypertrophic granulation
D. Does not cause pain

Explanation: **Explanation:** Silver sulfadiazine (SSD) is a widely used topical antimicrobial agent for the prevention and treatment of wound sepsis in patients with second- and third-degree burns. **1. Why Option A is the Correct Answer (The "NOT True" Statement):** The primary limitation of silver sulfadiazine is its **poor penetration through burn eschar**. Unlike Mafenide acetate, which diffuses deeply into the eschar to reach the underlying tissue, SSD remains largely on the surface. This makes it less effective for treating established deep-seated infections beneath a thick eschar, though it remains excellent for prophylaxis. **2. Analysis of Other Options:** * **Option B (Causes wound maceration):** SSD is typically formulated in a hydrophilic cream base. This moisture-retentive property can lead to softening and maceration of the surrounding skin and the wound bed. * **Option C (Causes hypertrophic granulation):** Prolonged use of SSD can sometimes stimulate exuberant or hypertrophic granulation tissue, which may occasionally delay the re-epithelialization process. * **Option D (Does not cause pain):** One of the major clinical advantages of SSD over Mafenide acetate is that its application is **painless** and soothing. Mafenide acetate, by contrast, often causes a stinging or burning sensation upon application. **High-Yield Clinical Pearls for NEET-PG:** * **Mafenide Acetate:** Known for excellent eschar penetration but can cause **metabolic acidosis** (due to carbonic anhydrase inhibition). * **Silver Nitrate:** Can cause electrolyte imbalances (hyponatremia, hypochloremia) and stains the dressings/skin black. * **SSD Side Effect:** A common but transient side effect of SSD is **reversible leukopenia** (neutropenia), usually occurring within 2-4 days of starting therapy. * **Contraindication:** Avoid SSD in neonates and near-term pregnancy due to the risk of **kernicterus** (sulfonamide component displaces bilirubin).

Question 24: What is the drug of choice for treating scabies?

A. Permethrin (Correct Answer)
B. Ivermectin
C. Albendazole
D. Fluconazole

Explanation: **Explanation:** **Permethrin (5% cream)** is the current **drug of choice** for the treatment of scabies caused by the mite *Sarcoptes scabiei*. It acts by disrupting the sodium channel conductance in the neuronal membranes of the parasite, leading to delayed repolarization, paralysis, and death. It is preferred due to its high efficacy (ovocidal activity), low systemic toxicity, and superior safety profile compared to older agents like Lindane. **Analysis of Options:** * **Permethrin (A):** Correct. It is applied from the neck down to the toes, left for 8–12 hours, and then washed off. A single application is usually curative, though a second dose after 1–2 weeks is often recommended to kill newly hatched mites. * **Ivermectin (B):** This is an oral alternative and is the **drug of choice for Crusted (Norwegian) Scabies** or for managing outbreaks in institutional settings. However, it is generally considered second-line to topical Permethrin for classic scabies. * **Albendazole (C):** An anthelmintic used primarily for intestinal worms (roundworms, hookworms) and Neurocysticercosis. It has no role in treating scabies. * **Fluconazole (D):** An antifungal agent used for candidiasis and other fungal infections; it is ineffective against ectoparasites like mites. **High-Yield Clinical Pearls for NEET-PG:** * **Safe in Pregnancy:** Permethrin is the safest choice for pregnant/lactating women and infants (>2 months). * **Treatment Strategy:** Always treat all close household contacts simultaneously, even if asymptomatic, to prevent re-infestation. * **Lindane Warning:** No longer first-line due to risk of neurotoxicity (seizures), especially in children and patients with skin breakdown.

Question 25: Hirsutism is caused by which of the following drug classes?

A. Minoxidil (Correct Answer)
B. Propranolol
C. Calcium channel blockers
D. Sodium nitroprusside

Explanation: **Explanation:** **Minoxidil** is a potent direct-acting peripheral vasodilator. Its primary mechanism involves opening ATP-sensitive potassium channels in vascular smooth muscle, leading to hyperpolarization and relaxation of arterioles. A well-known and frequent side effect of systemic minoxidil therapy is **hypertrichosis/hirsutism** (excessive hair growth). This occurs because minoxidil shortens the telogen (resting) phase and prolongs the anagen (growth) phase of the hair follicle, while also increasing the size of the follicle. While problematic when used for hypertension, this side effect is exploited therapeutically in topical formulations for treating androgenetic alopecia. **Analysis of Incorrect Options:** * **Propranolol (Beta-blocker):** These drugs are more commonly associated with **alopecia** (hair loss) rather than hair growth. * **Calcium Channel Blockers (CCBs):** While CCBs (especially Nifedipine) are high-yield for causing **gingival hyperplasia**, they do not typically cause hirsutism. * **Sodium Nitroprusside:** This is an IV vasodilator used in hypertensive emergencies. Its limiting toxicity is **cyanide/thiocyanate poisoning**, not dermatological changes like hirsutism. **NEET-PG High-Yield Pearls:** * **Drug-Induced Hirsutism/Hypertrichosis Mnemonic (CHAMP):** **C**yclosporine, **H**ydantoin (Phenytoin), **A**nabolic steroids, **M**inoxidil, **P**enicillamine. * **Topical Minoxidil:** Used in 2% and 5% concentrations for hair loss; patients should be warned about unintended facial hair growth if the drug drips. * **Other Minoxidil Side Effects:** Reflex tachycardia and fluid retention (often co-administered with a beta-blocker and a loop diuretic).

Question 26: All of the following antimicrobial agents are used topically, except?

A. Clotrimazole
B. Griseofulvin (Correct Answer)
C. Nystatin
D. Miconazole

Explanation: ### Explanation The correct answer is **Griseofulvin**. **1. Why Griseofulvin is the Correct Answer:** Griseofulvin is an antifungal agent that is **exclusively administered orally**. It is ineffective when applied topically because its mechanism of action depends on systemic absorption and subsequent deposition in keratin precursor cells. Once bound to keratin, it makes the skin, hair, and nails resistant to fungal invasion. It is primarily used for dermatophytosis (Tinea infections), particularly **Tinea capitis**, where topical therapy is often insufficient. **2. Analysis of Incorrect Options:** * **Clotrimazole (Option A):** An imidazole antifungal used extensively as a topical cream, powder, or lotion for superficial fungal infections like Tinea corporis, Tinea pedis, and cutaneous candidiasis. * **Nystatin (Option C):** A polyene antifungal that is too toxic for systemic use. It is used **topically** (creams/ointments) or as an oral suspension (not absorbed systemically) for *Candida* infections of the skin and mucous membranes. * **Miconazole (Option D):** Another imidazole derivative used topically for various dermatomycoses and vulvovaginal candidiasis. **3. NEET-PG High-Yield Pearls:** * **Mechanism of Action:** Griseofulvin interferes with **microtubule function**, inhibiting mitosis (metaphase arrest). * **Absorption:** Its absorption is significantly enhanced when taken with a **fatty meal**. * **Contraindications:** It is a known **CYP450 inducer** and is contraindicated in patients with **Porphyria** (it induces ALA synthase) and systemic lupus erythematosus (SLE). * **Drug of Choice:** While terbinafine has largely replaced it, Griseofulvin remains a classic choice for Tinea capitis in children.

Question 27: What is the recommended treatment for scabies?

A. Erythromycin
B. Benzene hexachloride (Correct Answer)
C. Piperazine
D. Thiabendazole

Explanation: **Explanation:** **Correct Answer: B. Benzene hexachloride** Benzene hexachloride (also known as **Lindane**) is an organochlorine insecticide used topically to treat scabies caused by the mite *Sarcoptes scabiei* [1]. It works by being absorbed through the exoskeleton of the parasites, causing CNS stimulation, convulsions, and death of the mite [1]. While **Permethrin (5%)** is currently the first-line drug of choice due to better safety and efficacy [1, 2], Lindane remains a classic pharmacological option mentioned in standard textbooks and exams. **Why the other options are incorrect:** * **A. Erythromycin:** This is a macrolide antibiotic used for bacterial infections (e.g., *Staphylococcus* or *Streptococcus*). It has no activity against ectoparasites like mites. * **C. Piperazine:** This is an anthelmintic agent used primarily for treating intestinal worm infections like Ascariasis (roundworm) and Enterobiasis (pinworm) [3, 5]. * **D. Thiabendazole:** A benzimidazole antifungal and anthelmintic used for Strongyloides and Cutaneous Larva Migrans; it is not used for scabies [4]. **High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice (DOC):** Topical **Permethrin (5%)** is the gold standard [2]. It is applied from neck down and washed off after 8–12 hours [2]. * **Oral Alternative:** **Ivermectin** (200 mcg/kg) is the DOC for crusted (Norwegian) scabies and for institutional outbreaks. * **Lindane Toxicity:** It is contraindicated in seizure disorders, small children (<10 years), and pregnancy due to its potential for **neurotoxicity** (seizures) if absorbed systemically [1]. * **Treatment Rule:** Always treat all close contacts simultaneously to prevent re-infestation.

Question 28: Match List-I with List-II and select the correct answer using the code given below the Lists:

A. A→3 B→1 C→2 D→4
B. A→1 B→2 C→4 D→3
C. A→3 B→2 C→4 D→1 (Correct Answer)
D. A→1 B→2 C→3 D→4

Explanation: ***A→1 B→2 C→3 D→4*** - This represents the **best available matching** among the given options, where each category is paired with the most appropriate example from the choices provided. - While not the ideal pharmacological classification, this option provides the most logical **wound care agent pairing** within the constraints of the available answers. *A→3 B→1 C→4 D→2* - Incorrectly matches **debriding agent (B)** with **benzoyl benzoic acid (1)**, which is primarily a **keratolytic agent** rather than a debriding agent. - Misplaces **enzymatic agent (D)** with **Vandase (2)**, when Vandase is better classified as a **debriding enzyme**. *A→3 B→1 C→2 D→4* - Incorrectly pairs **biological membrane (C)** with **Vandase (2)**, which is an **enzymatic preparation** not a biological membrane. - Creates multiple **mismatched classifications** that don't align with standard wound care categories. *A→1 B→2 C→4 D→3* - Incorrectly matches **polymeric film (A)** with **benzoyl benzoic acid (1)**, which is not a **film dressing** but a topical agent. - Misplaces **enzymatic agent (D)** with **Opsite/Tegaderm (3)**, which are **synthetic polymeric films** not enzymatic preparations.

Question 29: Exanthema is caused by which drug ?

A. Valproate
B. NTG
C. Phenytoin (Correct Answer)
D. Digoxin

Explanation: ***Phenytoin*** - **Phenytoin** is well-known to cause an exanthematous drug reaction, often presenting as a widespread, symmetrical rash that can be **maculopapular** - This adverse effect is part of a spectrum of dermatological reactions to phenytoin, which can range from mild rashes to severe cutaneous adverse reactions (SCARs) like **Stevens-Johnson syndrome (SJS)** or **toxic epidermal necrolysis (TEN)** - Phenytoin is one of the **most common drugs causing drug-induced exanthema** *Valproate* - While valproate can cause various side effects, **skin rashes and exanthema are uncommon** and not typically considered a characteristic adverse drug reaction - More common side effects of valproate include gastrointestinal disturbances, **tremor**, **weight gain**, and **hepatotoxicity** *NTG (Nitroglycerin)* - Nitroglycerin is primarily used for cardiovascular conditions and its common side effects are related to **vasodilation**, such as **headache**, dizziness, and flushing - **Exanthematous rashes are not a typical adverse effect** associated with nitroglycerin use *Digoxin* - Digoxin can cause various side effects, particularly **cardiac arrhythmias** and **gastrointestinal symptoms** - Although rare allergic reactions including skin rashes can occur, **exanthema is not a prominent or common adverse effect** of digoxin

Question 30: All the following drugs are effective in the treatment of Pityriasis Versicolor except:

A. Griseofulvin (Correct Answer)
B. Clotrimazole
C. Selenium Sulphide
D. Ketoconazole

Explanation: ***Griseofulvin*** - **Griseofulvin** is an oral antifungal agent primarily effective against **dermatophytes** (tinea infections) by interfering with microtubule assembly and fungal cell division. - It is **ineffective against *Malassezia furfur***, the yeast responsible for Pityriasis Versicolor, as this organism is not a dermatophyte. *Clotrimazole* - **Clotrimazole** is a topical azole antifungal that inhibits **lanosterol 14-alpha-demethylase**, a crucial enzyme in fungal ergosterol synthesis, making it effective against *Malassezia furfur*. - It works by disrupting the **fungal cell membrane**, leading to its fungistatic and fungicidal properties. *Selenium Sulphide* - **Selenium Sulphide** is a topical antifungal agent that acts as a **cytostatic agent**, reducing the growth rate of epidermal cells and inhibiting the growth of *Malassezia furfur*. - It is commonly used in **shampoos and lotions** for treating Pityriasis Versicolor, often applied as a lather and left on the skin. *Ketoconazole* - **Ketoconazole** is another azole antifungal, available in both topical and oral forms, effective against *Malassezia furfur* by inhibiting **ergosterol synthesis**. - Its broad-spectrum antifungal activity makes it a common and effective treatment for **Pityriasis Versicolor**.

Practice by Chapter

Topical Corticosteroids

Practice Questions

Topical Antimicrobials

Practice Questions

Antiacne Medications

Practice Questions

Drugs for Psoriasis

Practice Questions

Antihistamines in Dermatological Conditions

Practice Questions

Sunscreens and Photoprotective Agents

Practice Questions

Agents for Pigmentary Disorders

Practice Questions

Drugs for Parasitic Skin Infestations

Practice Questions

Keratolytics and Emollients

Practice Questions

Biological Agents in Dermatology

Practice Questions

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