WBR0509

Author	[[PageAuthor::Gonzalo A. Romero, M.D. [1]]]
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 androgenic 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, tadalafil - erectile dysfunction
Answer B	AnswerB::Competitive inhibitor of testosterone binding at androgen receptors
Answer B Explanation	AnswerBExp::flutamide - Nonsteroidal antiandrogen - Prostate Cancer
Answer C	AnswerC::Aromatase inhibitor
Answer C Explanation	AnswerCExp::exemestane - Breast Cancer
Answer D	AnswerD::Agonist of luteinizing hormone-releasing hormone (LHRH)
Answer D Explanation	AnswerDExp::leuprolide - Prostate Cancer - Endometriosis - Leiomyoma
Answer E	AnswerE::Selective inhibitior of 5-alpha-reductase
Answer E Explanation	AnswerEExp::finasteride
Right Answer	RightAnswer::E
Explanation	[[Explanation::Finasteride is used for BPH (benigh prostatic hyperplasia) and to treat male-pattern baldness,because it promotes hair growth. It is an 5 alfa-reductase inhibitor (normally converts testosterone to DHT), decreasing the conversion of testosterone to DHT (dihydrotestosterone). Educational Objective: References: First Aid 2014 page 589]]
Approved	Approved::No
Keyword	WBRKeyword::Testosterone agonist, WBRKeyword::testosterone antagonist
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::