Sunday, 8 November 2015

Medical Test Question: Tinea Corporis

A 23-year-old athletically built woman comes to the physician complaining of multiple red, ring-like lesions on her body. A careful history and physical reveals the woman has tinea corporis acquired while working on poorly cleaned yoga mats at a local gym. The physician prescribes a medicine to clear her erythematous lesions. After 15 days of treatment the lesions she returns to the office. While the lesions are clearing, she has noticed that patches of her skin have become darker than normal. Which of the following drugs did this patient most likely receive?

A Amphotericin B
B Fluconazole
C Flucytosine
D Itraconazole
E Ketoconazole

See answer below.











Answer-  E (Ketoconazole)

Explanation

 A Amphotericin B
Amphotericin B is an antifungal drug used to treat systemic mycoses. It acts by disrupting fungal wall synthesis by binding to ergosterol (a component of the cell wall). Adverse effects include fever and chills, decreased creatinine clearance, hypotension, and anemia.

 B Fluconazole
Fluconazole is an antifungal drug with the same mechanism of action as ketoconazole, but without the endocrine side effects. It has good penetration into the cerebrospinal fluid and is used to treat Cryptococcus neoformans. Adverse effects include nausea and vomiting.

 C Flucytosine
Flucytosine is an antifungal drug used solely in combination with amphotericin B to treat systemic Cryptococcus neoformans and systemic Candida. Adverse effects include pancytopenia, elevated liver enzyme levels, nausea, and vomiting.

 D Itraconazole
Itraconazole is an antifungal that lacks the endocrine effects of ketoconazole. It is used to treat blastomycosis and AIDS-associated histoplasmosis. Adverse effects include nausea and vomiting, as well as rash in immunocompromised patients.

 E Ketoconazole
Ketoconazole is an antifungal drug used to treat tinea corporis that acts by blocking the formation of fungal membrane sterols. It also has an endocrine effect because it blocks the enzyme desmolase/CYP-450scc, which is necessary for adrenal production of testosterone and cortisol from cholesterol. Free cortisol is responsible for feedback inhibition of the POMC gene, which codes for synthesis of ACTH, lipotropin, melanocyte-stimulating hormone, and some endogenous endorphins. Without desmolase activity to create cortisol, this feedback inhibition is removed and thus the POMC gene products are freely transcribed. Excessive melanocyte-stimulating hormone can cause increased integumentary pigmentation such as in patients with Addison disease. Other endocrine effects include decreased libido, impotence, and gynecomastia in men.

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