Drugs Used in Skin Disorders — MCQs

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

Question 61: Fixed drug eruptions can be seen more frequently with which of the following medications?

A. Penicillin
B. Sulfonamide (Correct Answer)
C. Roxithromycin
D. Cetirizine

Explanation: ***Sulfonamide*** - **Fixed drug eruptions (FDEs)** are particularly associated with sulfonamides due to their common use and mechanism of action, which can lead to localized, recurrent reactions upon re-exposure. - Sulfonamides, such as **sulfamethoxazole-trimethoprim**, are well-known triggers for these specific cutaneous adverse drug reactions. *Penicillin* - While penicillin can cause a wide variety of **hypersensitivity reactions**, including rashes and anaphylaxis, FDEs are not a typical or frequent presentation. - **Maculopapular rashes** and **urticaria** are more characteristic of penicillin allergies. *Cetirizine* - Cetirizine is an **antihistamine** primarily used to treat allergic reactions, and it is rarely associated with drug-induced skin eruptions. - It is generally considered a **safe medication** with a low incidence of adverse skin effects. *Roxithromycin* - Roxithromycin is a **macrolide antibiotic** and, while it can cause skin reactions, FDEs are uncommon. - Macrolides are more frequently linked to **generalized hypersensitivity reactions** or **photosensitivity**.

Question 62: The most potent topical corticosteroid is:

A. Betamethasone valerate cream 0.1%
B. Clobetasone butyrate cream 0.5%
C. Clobetasol propionate cream 0.05% (Correct Answer)
D. Hydrocortisone butyrate cream 0.1%

Explanation: ***Clobetasol propionate cream 0.05%*** - **Clobetasol propionate** is recognized as a **super high-potency (Class I)** topical corticosteroid, making it one of the most potent available. - It is often used for severe inflammatory skin conditions that are resistant to less potent corticosteroids. *Hydrocortisone butyrate cream 0.1%* - **Hydrocortisone butyrate** is a **medium-potency (Class IV)** corticosteroid, significantly less potent than clobetasol propionate. - While effective for mild to moderate dermatoses, it would not be considered the "most potent." *Betamethasone valerate cream 0.1%* - **Betamethasone valerate** is a **medium-potency (Class III/IV)** corticosteroid, depending on the specific formulation. - It falls in an intermediate range of potency, not reaching the super high potency of clobetasol propionate. *Clobetasone butyrate cream 0.5%* - **Clobetasone butyrate** is a **mild-potency (Class VI/VII)** corticosteroid, much less potent than clobetasol propionate despite the similar-sounding name. - It is typically used for less severe conditions or in more sensitive areas where stronger corticosteroids are contraindicated.

Question 63: What are the components of Whitfield's ointment?

A. 3% salicylic acid + 6% benzoic acid (Correct Answer)
B. 2% salicylic acid + 4% benzoic acid
C. 2% benzoic acid + 4% salicylic acid
D. 5% salicylic acid + 10% benzoic acid

Explanation: ***3% salicylic acid + 6% benzoic acid*** - **Whitfield's ointment** traditionally contains a combination of **3% salicylic acid** and **6% benzoic acid**. - **Salicylic acid** acts as a keratolytic agent, helping to shed dead skin cells, while **benzoic acid** provides antifungal properties. *5% salicylic acid + 10% benzoic acid* - While these concentrations of **salicylic acid** and **benzoic acid** are both used in dermatology for their respective properties, they do not represent the classic formulation of **Whitfield's ointment**. - This higher concentration might be used in other topical preparations but is not standard for Whitfield's. *2% salicylic acid + 4% benzoic acid* - These concentrations are **lower** than the standard formulation of **Whitfield's ointment**. - Using lower concentrations might reduce efficacy for conditions like **tinea pedis** where Whitfield's is often employed. *2% benzoic acid + 4% salicylic acid* - This option reverses the typical higher concentration of **benzoic acid** compared to **salicylic acid** in Whitfield's ointment and uses incorrect percentages. - The specific ratio and concentrations are crucial for the product's intended antifungal and keratolytic actions.

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

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Agents for Pigmentary Disorders

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Drugs for Parasitic Skin Infestations

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Keratolytics and Emollients

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Biological Agents in Dermatology

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