Drugs Used in Skin Disorders — MCQs

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

Question 41: Drug of choice in scabies in pregnant woman is -

A. Gamma Benzene Hexachloride
B. Ivermectin
C. Benzyl benzoate
D. Permethrin (Correct Answer)

Explanation: ***Permethrin*** - **Permethrin cream** (5%) is considered the **drug of choice** for scabies in pregnant women due to its high efficacy and excellent safety profile. - It has **minimal systemic absorption**, reducing potential risks to the developing fetus. *Gamma Benzene Hexachloride* - **Gamma Benzene Hexachloride (lindane)** is **not recommended** in pregnancy due to potential **neurotoxicity** and higher systemic absorption. - It can cause **seizures** and other central nervous system effects, especially in infants and young children. *Ivermectin* - **Ivermectin** is an oral medication that has **limited safety data** in pregnancy and is generally avoided unless topical treatments fail. - It is classified as **Pregnancy Category C** by the FDA, meaning animal studies have shown adverse effects on the fetus, but there are no adequate and well-controlled studies in humans. *Benzyl benzoate* - **Benzyl benzoate** is an older scabicide that can be **irritating to the skin** and is generally considered a second-line option. - While it has been used in pregnancy, **permethrin** is preferred due to its superior safety and lower irritation profile.

Question 42: Steroids are used in the Rx of the following diseases EXCEPT:

A. Pemphigus vulgaris
B. Chronic fungal infection (Correct Answer)
C. Erythema multiforme
D. Contact dermatitis

Explanation: ***Chronic fungal infection*** - **Steroids are absolutely contraindicated** in **chronic fungal infections** as they **suppress cell-mediated immunity**, leading to worsening of the infection and potential dissemination. - Corticosteroids promote fungal growth and can convert a localized infection into a systemic, life-threatening condition. - This is the **clearest contraindication** among the options. *Pemphigus vulgaris* - **Pemphigus vulgaris** is an **autoimmune blistering disease** where **high-dose systemic steroids are the first-line treatment**. - Corticosteroids (1-2 mg/kg/day of prednisolone) are essential for controlling autoantibody production and preventing life-threatening complications. - **Steroids are clearly indicated**, not contraindicated. *Erythema multiforme* - **Erythema multiforme** is typically a **self-limiting condition** managed primarily with **supportive care** (antipyretics, antihistamines, topical care). - **Systemic steroids are generally NOT recommended** as standard treatment and their use remains **controversial**. - However, in very rare severe cases with extensive mucosal involvement, some clinicians may consider a short course, making this **not an absolute contraindication** like fungal infections. *Contact dermatitis* - **Contact dermatitis** is commonly treated with **topical corticosteroids** as first-line therapy to reduce inflammation and pruritus. - In severe, widespread cases, a short course of **oral steroids** may be prescribed. - **Steroids are clearly indicated** for this condition.

Question 43: Permethrin is used in the topical treatment of:

A. Psoriasis
B. Scabies (Correct Answer)
C. Acne
D. Tinea

Explanation: ***Scabies*** - **Permethrin** cream, typically 5%, is the **first-line treatment for scabies**, an infestation caused by the mite *Sarcoptes scabiei* [1], [2]. - It works by **neurotoxic action** on the mite, leading to paralysis and death [1]. - Applied from neck down, left on for 8-14 hours, then washed off [2]. *Psoriasis* - Psoriasis is a chronic **autoimmune skin condition** characterized by rapid skin cell turnover, forming scaly plaques [5]. - Treatment involves **corticosteroids, vitamin D analogs, retinoids, or biologics**; permethrin is not indicated [4]. - Permethrin has no anti-inflammatory or immunomodulatory properties. *Acne* - Acne is a multifactorial condition involving **sebaceous glands and hair follicles**, leading to comedones and inflammatory lesions. - Treatment typically includes **topical retinoids, benzoyl peroxide, antibiotics**, or oral medications; permethrin has no role [4]. - Permethrin does not affect sebum production or *Cutibacterium acnes*. *Tinea* - Tinea refers to **fungal infections** of the skin, hair, or nails (ringworm, athlete's foot) [3]. - These infections require **topical or oral antifungal agents** (e.g., azoles, terbinafine), not permethrin [3]. - Permethrin is an insecticide with no antifungal activity.

Question 44: A 17 year old girl had been taking a drug for the treatment of acne for the last 2 years, which has led to pigmentation. Which drug could it be?

A. Doxycycline
B. Minocycline (Correct Answer)
C. Clindamycin
D. Azithromycin

Explanation: ***Minocycline*** - **Minocycline** is a **tetracycline** antibiotic commonly used for acne and is notorious for causing various forms of **pigmentation**, including blue-gray discoloration of the skin, scars, and teeth, especially with long-term use. - This pigmentation is due to the formation of **insoluble chelates** of minocycline with iron and melanin within tissues. *Doxycycline* - While also a **tetracycline**, **doxycycline** is less commonly associated with significant **skin pigmentation** compared to minocycline at standard acne treatment doses. - Its side effect profile for pigmentation usually involves **photosensitivity** or **tooth discoloration** in children, not generally diffuse skin discoloration in adolescents. *Clindamycin* - **Clindamycin** is a **lincosamide antibiotic** primarily used topically or orally for acne, but it does not cause **pigmentation** as a known side effect. - Its main systemic side effect concern is **Clostridioides difficile-associated diarrhea (CDAD)**. *Azithromycin* - **Azithromycin** is a **macrolide antibiotic** and is not typically associated with **skin pigmentation** as a side effect. - It is sometimes used for acne, but its side effects are primarily **gastrointestinal** (nausea, vomiting, diarrhea).

Question 45: Podophyllum resin is indicated in the treatment of:

A. Pemphigus.
B. Psoriasis.
C. Condyloma acuminata. (Correct Answer)
D. Condylomata lata.

Explanation: ***Condyloma acuminata.*** - **Podophyllum resin** is a cytotoxic agent that inhibits cell division and is commonly used as a topical treatment for **genital warts (condyloma acuminata)**. - Its mechanism involves arresting cells in metaphase by interfering with microtubule assembly, leading to necrosis of the wart tissue. *Pemphigus.* - **Pemphigus** is an autoimmune blistering disease of the skin and mucous membranes, not treated with podophyllum resin. - Treatment typically involves **systemic corticosteroids** and other immunosuppressive agents. *Psoriasis.* - **Psoriasis** is a chronic inflammatory skin condition characterized by accelerated epidermal cell turnover, and **podophyllum resin is not indicated for its treatment**. - Management often includes topical corticosteroids, vitamin D analogs, phototherapy, and systemic immunomodulators. *Condylomata lata.* - **Condylomata lata** are broad, flat, moist lesions characteristic of **secondary syphilis**, and they are highly infectious. - Treatment involves **penicillin** for syphilis, as condylomata lata are a manifestation of the underlying spirochete infection.

Question 46: 23 years old woman complains of recurrent acne over her face. History revealed that she had taken topical antibiotics for her acne without any significant improvement. Which one of the following tetracyclines is most preferred for her acne?

A. Doxycycline (Correct Answer)
B. Oxytetracycline
C. Minocycline
D. Demeclocycline

Explanation: ***Doxycycline*** - **Doxycycline** is a commonly preferred tetracycline for acne due to its **anti-inflammatory properties** and efficacy against *P. acnes* at sub-antimicrobial doses. - Its **longer half-life** allows for once-daily dosing, improving patient adherence compared to other tetracyclines. *Oxytetracycline* - While effective against *P. acnes*, **oxytetracycline** generally requires higher doses and more frequent administration, which can lead to poorer patient compliance. - It often causes **gastric irritation**, making it less favorable for long-term acne management. *Minocycline* - **Minocycline** is also effective for acne but is associated with a higher risk of **side effects** like dizziness, headache, and hyperpigmentation (e.g., skin, teeth). - Its potential for **drug-induced lupus-like syndrome** and **hepatotoxicity** makes it less preferred compared to doxycycline, especially for prolonged use. *Demeclocycline* - **Demeclocycline** is primarily used as an **ADH antagonist** for treating syndrome of inappropriate antidiuretic hormone (SIADH) and is not a first-line treatment for acne. - It has a higher incidence of **photosensitivity** and overall greater renal toxicity compared to other tetracyclines, making it unsuitable for acne.

Question 47: Imiquimod is used in the treatment of -

A. Anogenital warts (Correct Answer)
B. Tinea versicolor
C. Melanoma
D. Sezary syndrome

Explanation: ***Anogenital warts*** - **Imiquimod** is a topical immune response modifier primarily used for treating **external anogenital warts** caused by Human Papillomavirus (HPV). - It works by stimulating the immune system to produce **interferon-alpha** and other cytokines, which fight the viral infection. *Tinea versicolor* - **Tinea versicolor** is a superficial fungal infection caused by **Malassezia species**. - It is typically treated with **topical antifungal agents** (e.g., ketoconazole, selenium sulfide) or oral antifungals in widespread cases. *Melanoma* - **Melanoma** is a serious form of skin cancer that requires treatment with **surgical excision**, chemotherapy, radiation, or targeted therapies/immunotherapy. - **Imiquimod** is not a standard treatment for melanoma, although it has been investigated in some superficial or early forms, its use is limited to **superficial basal cell carcinoma** and **actinic keratosis**. *Sezary syndrome* - **Sézary syndrome** is an advanced and aggressive form of **cutaneous T-cell lymphoma (CTCL)**, characterized by erythroderma, lymphadenopathy, and circulating malignant T-cells. - Treatment involves systemic therapies such as **chemotherapy**, photopheresis, radiation, and biological agents. Imiquimod has no role in its management.

Question 48: Which of the following drugs is NOT used in scabies?

A. Benzene hexachloride
B. Ciclopirox oleamine (Correct Answer)
C. Permethrin
D. Crotamiton

Explanation: ***Ciclopirox oleamine*** - **Ciclopirox oleamine** is an **antifungal** medication used to treat various fungal skin infections, such as tinea infections and candidiasis. - It has no known activity against the **Sarcoptes scabiei mite**, which causes scabies. *Benzene hexachloride* - **Benzene hexachloride**, specifically **lindane**, is an **organochloride insecticide** that has been used topically to treat scabies. - Its use has become more limited due to concerns about neurotoxicity, particularly in infants and individuals with seizures. *Permethrin* - **Permethrin** cream (5%) is a **pyrethroid insecticide** and is considered a **first-line treatment** for scabies due to its high efficacy and low toxicity. - It works by disrupting the nervous system of the mite, leading to paralysis and death. *Crotamiton* - **Crotamiton** is an **antipruritic** and **scabicidal** agent that is used to treat scabies, as well as to relieve itching. - It is less effective than permethrin for scabies but can be an alternative, especially when permethrin is contraindicated or not tolerated.

Question 49: Which drug can be given as a nail lacquer treatment in onychomycosis?

A. Terbinafine
B. Ciclopirox olamine (nail lacquer) (Correct Answer)
C. Nystatin
D. Itraconazole

Explanation: ***Ciclopirox olamine (nail lacquer)*** - **Ciclopirox olamine** is an antifungal agent formulated as a nail lacquer, specifically designed for topical application in **onychomycosis**. - Its mechanism involves interfering with fungal cellular processes, transported directly to the nail bed where the fungal infection resides. *Terbinafine* - **Terbinafine** is primarily an **oral antifungal** medication or available as a topical cream, but not typically in a nail lacquer formulation for onychomycosis. - While highly effective against dermatophytes causing onychomycosis, its systemic absorption is key to its efficacy when administered orally. *Nystatin* - **Nystatin** is an antifungal agent primarily effective against **Candida** species and is not typically used for dermatophyte-induced onychomycosis, nor is it commonly formulated as a nail lacquer. - Its broad spectrum is limited in this context, as most onychomycosis cases are caused by dermatophytes, which are less susceptible to nystatin. *Itraconazole* - **Itraconazole** is a **systemic antifungal** medication, effective in treating onychomycosis, but it is not available as a nail lacquer. - It works by inhibiting fungal cytochrome P450 enzymes, which are critical for ergosterol synthesis, a component of the fungal cell membrane.

Question 50: What is the mechanism of vitamin D analogues in psoriasis?

A. T cell suppression
B. Antimicrobial action
C. Antipruritic effect
D. Keratinocyte differentiation (Correct Answer)

Explanation: ***Keratinocyte differentiation*** - Vitamin D analogues bind to the **vitamin D receptor (VDR)** in keratinocytes, promoting their **differentiation** and inhibiting their abnormal proliferation. - This action helps to normalize the growth and maturation of skin cells, which are excessively produced in psoriasis. *T cell suppression* - While **T-cell activity** plays a crucial role in psoriasis pathogenesis, vitamin D analogues primarily target keratinocyte function rather than directly suppressing T cells. - Other treatments like **corticosteroids** or **biologics** are more directly involved in immune suppression. *Antimicrobial action* - Vitamin D itself has some **immunomodulatory effects** and can influence antimicrobial peptides, but this is not the primary mechanism of its analogues in treating psoriasis. - The direct and significant impact is on **keratinocyte behavior**. *Antipruritic effect* - Relieving **pruritus (itching)** can be a secondary benefit of resolving psoriatic lesions, but vitamin D analogues do not have a direct **antipruritic mechanism**. - Their primary action is to address the underlying **pathophysiology** of the disease.

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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