WBR0509

Author	[[PageAuthor::Serge Korjian M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Reproductive
Prompt	[[Prompt::A 31-year-old man presents to the dermatology clinic for hair loss. The patient reports progressive hairline regression and hair loss mainly localized above the temples and at the vertex. He also explains that he has a strong family history of androgenetic alopecia, and cannot stand the idea of going completely bald. The patient has tried many topical products intended for hair loss, which have not been very helpful. You consider using an agent that is also approved for the treatment of benign prostatic hyperplasia. Which of the following is the most likely mechanism of action of this drug?]]
Answer A	AnswerA::Phosphodiesterase 5 (PDE5) inhibitor
Answer A Explanation	AnswerAExp::Sildenafil and tadalafil are examples of phosphodiesterase 5 (PDE5) inhibitors. These drugs are used to treat erectile dysfunction and are not used for the treatment of androgenetic alopecia.
Answer B	AnswerB::Competitive inhibitor of testosterone binding at androgen receptors
Answer B Explanation	AnswerBExp::Flutamide is a nonsteroidal antiandrogen that acts as a competitive inhibitor of testosterone binding at androgen receptors. It is used in the treatment of prostate cancer and is not used for the treatment of androgenetic alopecia.
Answer C	AnswerC::Aromatase inhibitor
Answer C Explanation	AnswerCExp::Exemestane acts as an aromatase inhibitor to decrease peripheral estrogen production. It is used in the treatment of estrogen receptor-positive breast cancer and cannot be used to treat androgenetic alopecia.
Answer D	AnswerD::Agonist of luteinizing hormone-releasing hormone (LHRH)
Answer D Explanation	[[AnswerDExp::Leuprolide acts as an agonist of luteinizing hormone-releasing hormone (LHRH) causing a disruption of gonadotropin release if given continuously. It is used in the treatment of prostate cancer, endometriosis, and leiomyoma and cannot be used to treat androgenetic alopecia.]]
Answer E	AnswerE::Selective inhibitor of 5-alpha-reductase
Answer E Explanation	AnswerEExp::Finasteride is a selective inhibitor of 5-alpha-reductase used in the treatment of androgenetic alopecia.
Right Answer	RightAnswer::E
Explanation	[[Explanation::Finasteride is a selective inhibitor of 5-alpha-reductase that suppresses serum dihydrotestosterone (DHT) levels by inhibiting the conversion of testosterone to DHT. Finasteride may be used alone or in combination with alpha-blockers to treat benign prostatic hyperplasia (BPH). Another indication finasteride is slowing the progression of androgenetic alopecia. As androgenetic alopecia is partly caused by the effect of DHT at the pilosebaceous unit, decreasing DHT production is associated with slower progression of hair loss. Finasteride actively delays hair loss while the medication is being administered; however, similarly to other medical options for the treatment of alopecia, its effect does not last once the drug is discontinued. Common side effects include erectile dysfunction, decreased libido, and breast enlargement. Educational Objective: Finasteride is a selective inhibitor of 5-alpha-reductase used in the treatment of androgenetic alopecia. References: Kaufman KD, Olsen EA, Whiting D, et al. Finasteride in the treatment of men with androgenetic alopecia. Finasteride Male Pattern Hair Loss Study Group. J Am Acad Dermatol. 1998;39(4 Pt 1):578-89.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Androgenetic alopecia, WBRKeyword::Male pattern baldness, WBRKeyword::baldness, WBRKeyword::Finasteride, WBRKeyword::5-alpha-reductase, WBRKeyword::DHT, WBRKeyword::Testosterone
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