Drugs Used in Skin Disorders — MCQs

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

Question 11: Acanthosis nigricans can be caused by which drug?

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

Explanation: **Explanation:** Nicotinic acid (Niacin), used in the treatment of dyslipidemia, is a well-known pharmacological cause of **Acanthosis Nigricans (AN)**. The underlying mechanism involves the drug’s ability to induce insulin resistance [1] and increase the expression of **Epidermal Growth Factor Receptors (EGFR)** on keratinocytes. This leads to the characteristic hyperpigmented, velvety plaques typically found in intertriginous areas like the axilla and neck. **Analysis of Options:** * **Nicotinic acid (Correct):** High doses of Niacin can trigger AN. Other common side effects include cutaneous flushing (mediated by prostaglandins) and hyperuricemia. * **Amphotericin-B:** This antifungal is notorious for its nephrotoxicity and infusion-related reactions ("shake and bake" symptoms), but it does not cause AN. * **Ketoconazole:** An antifungal known for inhibiting steroid synthesis, leading to gynecomastia and decreased libido. It is also associated with hepatotoxicity. * **Nalidixic acid:** A quinolone antibiotic primarily associated with photosensitivity reactions and intracranial hypertension (pseudotumor cerebri) in children. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-induced AN:** Other culprits include systemic glucocorticoids, oral contraceptives, and growth hormone therapy. * **Malignant AN:** If AN appears suddenly and is extensive (especially involving the palms/tripe palms), it is often a paraneoplastic sign of **Gastric Adenocarcinoma**. * **Niacin Flushing:** This can be mitigated by pre-treating with **Aspirin**, which inhibits the prostaglandin-mediated vasodilation.

Question 12: Which of the following drugs can cause hirsutism?

A. Minoxidil
B. Cyclosporine
C. Tacrolimus
D. All of the above (Correct Answer)

Explanation: **Explanation:** The correct answer is **D. All of the above**. Hirsutism is defined as the excessive growth of terminal hair in females in a male-pattern distribution. Several systemic and topical drugs can induce this condition through various mechanisms. 1. **Minoxidil:** Originally an antihypertensive (K+ channel opener), its most famous side effect is hypertrichosis/hirsutism. It acts by increasing blood flow to hair follicles and prolonging the anagen (growth) phase. While used topically for alopecia, systemic absorption or accidental contact can lead to unwanted hair growth. 2. **Cyclosporine:** This calcineurin inhibitor, used as an immunosuppressant, causes hirsutism in approximately 80% of patients. The mechanism involves the stimulation of quiescent hair follicles into the anagen phase and the inhibition of hair follicle apoptosis. 3. **Tacrolimus:** Like cyclosporine, tacrolimus is a calcineurin inhibitor. Although it is generally considered to have a slightly lower incidence of hirsutism compared to cyclosporine, it remains a well-documented causative agent. **High-Yield Clinical Pearls for NEET-PG:** * **Drug-Induced Hirsutism vs. Hypertrichosis:** While often used interchangeably in exams, *hirsutism* is androgen-dependent (male pattern), whereas *hypertrichosis* is generalized hair growth. * **Other common drugs causing hirsutism/hypertrichosis:** Phenytoin, Glucocorticoids, Acetazolamide, and Anabolic steroids. * **Management:** For drug-induced cases, the first step is discontinuation. Pharmacological treatment for hirsutism includes **Spironolactone** (anti-androgen) or **Eflornithine** (topical ornithine decarboxylase inhibitor). * **Cyclosporine Side Effects Mnemonic (5 H's):** **H**irsutism, **H**yperplasia (Gingival), **H**ypertension, **H**yperlipidemia, and **H**yperkalemia (along with Nephrotoxicity).

Question 13: Which of the following drugs is used as a nail lacquer for fungal infections?

A. Terbinafine (Correct Answer)
B. Itraconazole
C. Nystatin
D. Fluconazole

Explanation: **Explanation:** The correct answer is **Terbinafine**. **1. Why Terbinafine is Correct:** Terbinafine is an allylamine antifungal that inhibits the enzyme **squalene epoxidase**, leading to a deficiency of ergosterol and a toxic accumulation of squalene within the fungal cell. For the treatment of **Onychomycosis** (fungal infection of the nails), terbinafine is available in various formulations, including oral tablets and **topical nail lacquers**. Nail lacquers are specialized vehicles designed to penetrate the hard keratin of the nail plate to deliver the drug to the nail bed. Other common nail lacquers used clinically include **Ciclopirox** and **Amorolfine**. **2. Why the Other Options are Incorrect:** * **Itraconazole:** While it is a first-line systemic treatment for onychomycosis (often used in "pulse therapy"), it is not typically formulated as a nail lacquer. It works by inhibiting 14-alpha-demethylase. * **Nystatin:** This is a polyene antifungal used primarily for **Candida** infections of the skin and mucous membranes (e.g., oral thrush). It is not effective against dermatophytes (the most common cause of nail infections) and is not used as a lacquer. * **Fluconazole:** This is an azole used systemically for various fungal infections. While it can be used orally for onychomycosis, it lacks a standard nail lacquer formulation. **3. High-Yield Clinical Pearls for NEET-PG:** * **Drug of Choice:** Oral Terbinafine is considered the DOC for dermatophytic onychomycosis. * **Adverse Effect:** Monitor Liver Function Tests (LFTs) with oral terbinafine as it can cause hepatotoxicity. * **Other Lacquers:** If Terbinafine is not in the options, look for **Amorolfine** (inhibits delta-14-reductase and delta-7,8-isomerase) or **Ciclopirox**. * **Squalene Epoxidase:** Remember that Terbinafine is **fungicidal**, whereas azoles are generally fungistatic.

Question 14: All of the following drugs are known to cause hirsutism except:

A. Cycloserine
B. Phenobarbitone
C. Phenytoin (Correct Answer)
D. Mycophenolate

Explanation: **Explanation:** The question asks for the drug that does **not** cause hirsutism. However, there is a common point of confusion in pharmacological literature regarding **Phenytoin**. Phenytoin is a classic, well-documented cause of **hirsutism** (and gingival hyperplasia). Therefore, in a standard "except" question, Phenytoin would typically be an incorrect choice. However, looking at the options provided: * **Phenytoin (Option C):** A classic inducer of hirsutism. * **Phenobarbitone (Option B):** Like many anti-epileptics, it is associated with hirsutism. * **Cycloserine (Option A):** An anti-tubercular drug known to cause hirsutism. * **Mycophenolate Mofetil (Option D):** This is an immunosuppressant that is actually associated with **alopecia** (hair loss) rather than hair growth. **Clinical Pearl:** In the context of NEET-PG, it is vital to distinguish between **Hirsutism** (androgen-dependent male-pattern hair growth in females) and **Hypertrichosis** (androgen-independent generalized hair growth). **High-Yield List of Drugs Causing Hirsutism/Hypertrichosis:** 1. **Antiepileptics:** Phenytoin, Phenobarbitone. 2. **Immunosuppressants:** Cyclosporine (Note: Mycophenolate and Tacrolimus usually cause alopecia). 3. **Vasodilators:** Minoxidil, Diazoxide. 4. **Hormones:** Anabolic steroids, Danazol, Progestins. 5. **Others:** Acetazolamide, Psoralens, Zidovudine. *Note: If this specific question identifies Phenytoin as the "except" answer in a mock key, it is likely a technical error in the question bank, as Mycophenolate is the most pharmacologically sound "except" choice due to its association with hair loss.*

Question 15: Skin pigmentation is caused by:

A. Methotrexate
B. Dactinomycin
C. Cyclophosphamide
D. Busulphan (Correct Answer)

Explanation: **Explanation:** **Busulphan** is an alkylating agent primarily used in the treatment of Chronic Myeloid Leukemia (CML) and as a conditioning agent before bone marrow transplantation. A classic and high-yield side effect of Busulphan is **generalized hyperpigmentation**, which often mimics the bronze skin seen in Addison’s disease. This occurs due to increased melanin production and is frequently accompanied by other symptoms like pulmonary fibrosis ("Busulphan lung") and adrenal insufficiency-like syndrome. **Analysis of Incorrect Options:** * **A. Methotrexate:** This folate antagonist is more commonly associated with photosensitivity, alopecia, and mucosal ulcerations (stomatitis) rather than generalized skin pigmentation. * **B. Dactinomycin:** Also known as Actinomycin D, this drug is a potent vesicant. Its primary dermatological concern is severe soft tissue necrosis if extravasated and "radiation recall" phenomenon, but not systemic pigmentation. * **C. Cyclophosphamide:** While it can cause nail pigmentation (melanonychia) and occasionally pigmentation of the palms and soles, it is not the classic answer for generalized skin pigmentation compared to Busulphan. Its hallmark toxicity is hemorrhagic cystitis. **High-Yield Clinical Pearls for NEET-PG:** * **Busulphan Triad:** Hyperpigmentation, Pulmonary Fibrosis, and Adrenal Insufficiency (pseudo-Addison’s). * **Other drugs causing skin pigmentation:** Bleomycin (flagellate dermatosis), Clofazimine (reddish-brown discoloration), Chloroquine (bluish-grey), and Amiodarone (blue-grey "Smurf" skin). * **Mnemonic:** "Busulphan burns the skin (pigmentation) and the lungs (fibrosis)."

Question 16: In terms of equivalent concentrations, in which topical preparation are steroids generally considered more potent?

A. Gel
B. Cream
C. Ointment (Correct Answer)
D. Lotion

Explanation: **Explanation:** The potency of a topical corticosteroid is determined not only by the drug molecule itself but also by the **vehicle** (base) in which it is formulated. **Why Ointment is the Correct Answer:** Ointments are primarily oil-based (greasy) and provide the highest level of **occlusion**. Occlusion increases the hydration of the stratum corneum, which significantly enhances the penetration and absorption of the steroid into the skin. By trapping moisture and preventing evaporation, ointments ensure a higher concentration of the drug reaches the deeper layers of the epidermis compared to other vehicles. Therefore, for the same concentration of a steroid, an ointment is more potent than a cream or lotion. **Analysis of Incorrect Options:** * **Cream (B):** These are emulsions of oil in water. They are less occlusive than ointments and contain preservatives that can be irritating. They are preferred for "weeping" lesions but offer lower drug delivery. * **Lotion (D) & Gel (A):** These have high water or alcohol content and provide minimal to no occlusion. They are useful for hairy areas or large surfaces but have the lowest potency due to rapid evaporation and poor skin penetration. **High-Yield Clinical Pearls for NEET-PG:** * **Rule of Thumb:** Potency ranking by vehicle: **Ointment > Cream > Lotion.** * **Clinical Choice:** Use **Ointments** for dry, thick, or hyperkeratotic lesions (e.g., chronic plaque psoriasis) and **Creams/Lotions** for moist, intertriginous, or hairy areas. * **Side Effects:** Prolonged use of high-potency steroids can lead to skin atrophy, striae, and telangiectasia. * **Absorption:** Absorption is highest in areas with thin skin (Face, Scrotum, Axilla) and lowest in areas with thick skin (Palms, Soles).

Question 17: Which of the following is true about minoxidil?

A. Increases hair growth
B. Antihypertensive
C. Both increases hair growth and is antihypertensive (Correct Answer)
D. Neither increases hair growth nor is antihypertensive

Explanation: Minoxidil is a potent **K+ channel opener** that acts as a direct-acting peripheral vasodilator [1, 2]. Its pharmacological profile makes it unique for two distinct clinical applications: 1. **Antihypertensive Action:** By opening ATP-sensitive potassium channels in vascular smooth muscle, it causes membrane hyperpolarization, leading to relaxation of arterioles. This reduces peripheral vascular resistance and lowers blood pressure. Clinically, it is reserved for **severe or refractory hypertension** that does not respond to standard triple-drug regimens [1, 2]. 2. **Hair Growth (Trichogenic) Action:** When applied topically, minoxidil promotes hair growth by increasing blood flow to hair follicles (via vasodilation) and shortening the resting phase (telogen) while prolonging the growth phase (anagen) of the hair cycle. It is a first-line treatment for **Androgenetic Alopecia** (male and female pattern baldness) [2, 3]. **Analysis of Options:** * **Option A & B:** While both are true, they are incomplete on their own. Minoxidil possesses both properties simultaneously. * **Option D:** This is incorrect as it contradicts the established pharmacological uses of the drug. **High-Yield NEET-PG Pearls:** * **Side Effects:** Significant systemic side effects include **reflex tachycardia** and **fluid retention** (edema). Therefore, it is almost always co-administered with a Beta-blocker and a Loop diuretic [1, 2]. * **Hypertrichosis:** Unwanted facial hair growth is a common side effect when used systemically for hypertension [2]. * **Mechanism:** It is a prodrug; it must be converted to **minoxidil sulfate** by the enzyme sulfotransferase to become active [3].

Question 18: Which of the following is NOT a use of Polydimethylsiloxane?

A. Antifoaming agent
B. Hydraulic fluids
C. Skin moisturizing agent
D. Hair coloring agent (Correct Answer)

Explanation: **Explanation:** **Polydimethylsiloxane (PDMS)**, commonly known as **Dimethicone**, is a silicon-based polymer widely used in medicine and industry due to its inert, non-toxic, and water-repellent properties. **Why Option D is Correct:** Polydimethylsiloxane is **not** used as a hair coloring agent. Hair dyes typically consist of oxidative chemicals (like p-phenylenediamine), ammonia, or metallic salts to alter pigment. While PDMS is frequently added to hair conditioners and shampoos to provide shine and reduce frizz by coating the hair shaft, it lacks any pigment-altering capabilities. **Analysis of Incorrect Options:** * **Antifoaming agent (Option A):** Dimethicone reduces the surface tension of gas bubbles. In clinical practice, it is used as an **anti-flatulent** (often combined with antacids) to coalesce intestinal gas bubbles, making them easier to expel. * **Hydraulic fluids (Option B):** Due to its thermal stability and excellent rheological properties, PDMS is used industrially in hydraulic fluids, lubricants, and heat transfer fluids. * **Skin moisturizing agent (Option C):** In dermatology, it acts as an **occlusive emollient**. It forms a protective, water-resistant barrier on the stratum corneum, preventing transepidermal water loss (TEWL). It is a mainstay in barrier creams for diaper rash and contact dermatitis. **High-Yield Clinical Pearls for NEET-PG:** * **Head Lice:** High-concentration Dimethicone is used as a physical pediculicide; it kills lice by suffocating them (blocking their spiracles) rather than through neurotoxicity. * **Simethicone:** This is a mixture of PDMS and silicon dioxide, used specifically for gastrointestinal gas relief. * **Surgical Use:** It is used in vitreoretinal surgery as an intraocular tamponade (silicone oil).

Question 19: Isotretinoin is:

A. A vitamin A analogue
B. Used in cystic acne
C. Safe in pregnancy (Correct Answer)
D. Used in psoriasis

Explanation: **Explanation:** Isotretinoin (13-cis-retinoic acid) is a systemic retinoid and a first-generation **Vitamin A analogue**. It is the most effective treatment for severe, recalcitrant **nodulocystic acne** because it addresses all four pathogenic factors: sebum production, follicular hyperkeratosis, *C. acnes* colonization, and inflammation. **Analysis of Options:** * **A & B (Incorrect in the context of the "Correct" label):** While Isotretinoin *is* a Vitamin A analogue and *is* used in cystic acne, these are true statements. In many MCQ formats, if a single "correct" answer is pre-marked (as in this prompt), it usually indicates a test of specific contraindications or properties. However, **Option C is medically incorrect**—Isotretinoin is highly **teratogenic**. * **C (The marked answer):** This is a **distractor or an error in the provided key.** Isotretinoin is strictly contraindicated in pregnancy (FDA Category X). It causes "Retinoid Embryopathy" (craniofacial, cardiac, and CNS defects). * **D (Incorrect):** While some retinoids (like Acitretin) are used for psoriasis, Isotretinoin is primarily indicated for acne. **Clinical Pearls for NEET-PG:** 1. **Teratogenicity:** Female patients must follow the **iPLEDGE program**, requiring two forms of contraception and two negative pregnancy tests before starting therapy. Contraception must continue for 1 month after stopping. 2. **Adverse Effects:** Most common is **Cheilitis** (dry lips). High-yield systemic effects include **hypertriglyceridemia**, hepatotoxicity, and psychiatric symptoms (depression/suicidal ideation). 3. **Monitoring:** Baseline and periodic monitoring of Liver Function Tests (LFTs) and Lipid profiles are mandatory. *Note: In a standard exam, Options A and B are scientifically true, while C is a dangerous medical fallacy. Always prioritize "Teratogenicity" as the most important clinical fact regarding Isotretinoin.*

Question 20: All are side effects of steroids except?

A. Skin atrophy
B. Telangiectasia
C. Folliculitis
D. Photosensitivity (Correct Answer)

Explanation: **Explanation:** The correct answer is **Photosensitivity**. Topical and systemic corticosteroids are known for their anti-inflammatory and immunosuppressive properties, but they do not typically cause photosensitivity. In fact, steroids are sometimes used to *treat* certain photodermatoses (like Polymorphous Light Eruption) due to their ability to suppress the immune response in the skin. **Why the other options are incorrect (Side effects of Steroids):** * **Skin Atrophy (Option A):** This is the most common local side effect. Steroids inhibit keratinocyte proliferation and reduce collagen synthesis by fibroblasts, leading to thinning of the epidermis and dermis. * **Telangiectasia (Option B):** Chronic steroid use leads to the release of nitric oxide and permanent dilation of superficial dermal capillaries, appearing as fine red lines on the skin. * **Folliculitis (Option C):** Steroids cause local immunosuppression and can alter the skin flora, leading to "Steroid Acne" or "Steroid Folliculitis." Unlike common acne, steroid-induced eruptions are typically monomorphic (all lesions at the same stage). **High-Yield Clinical Pearls for NEET-PG:** * **Tachyphylaxis:** This refers to the rapid decrease in response to a drug (tolerance) after repeated use, a common phenomenon with topical steroids. * **Iatrogenic Cushing’s Syndrome:** Can occur even with topical steroids if applied over large surface areas, under occlusion, or on thin skin (face/intertriginous areas). * **Striae Distensae:** Steroids cause irreversible linear scars (stretch marks) due to dermal collagen degradation. * **Glaucoma/Cataracts:** A critical side effect if potent steroids are applied chronically near the eyelids.

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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