WBR0510

Author	[[PageAuthor::Gonzalo A. Romero, M.D. [1]]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology, MainCategory::Physiology
Sub Category	SubCategory::Endocrine, SubCategory::Reproductive
Prompt	[[Prompt::A pharmacist is eager to study different models in reproductive pharmacology. He is very passionate about translational research. He is planning a study with mice in order to determine the effects of a novel drug called “Pharma-WBR”. He knows that the drug is supposed to work in the hypothalamus, to regulate the release of different pituitary hormones. He measures serum concentration and determines that the drug causes different changes in FSH and LH if used continuously or pulsatile. He finds analogy of a drug existing in the market. Which of the following drugs has a similar mechanism of action as “Pharma-WBR”?]]
Answer A	AnswerA::Flutamide
Answer A Explanation	[[AnswerAExp::Incorrect. Flutamide is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor used in prostate cancer.]]
Answer B	AnswerB::Finasteride
Answer B Explanation	[[AnswerBExp::Incorrect. Finasteride is a 5 alfa-reductase inhibitor used to treat BPH and male-pattern baldness.]]
Answer C	AnswerC::Mifepristone
Answer C Explanation	[[AnswerCExp::Incorrect. Mifepristone is a competitive inhibitor of progestins at the progesterone receptors. It is used to terminate pregnancy in combination with misoprostol (PGE1 analog).]]
Answer D	AnswerD::Ketoconazol
Answer D Explanation	[[AnswerDExp::Incorrect.]]
Answer E	AnswerE::Leuprolide
Answer E Explanation	[[AnswerEExp::Correct. See overall explanation.]]
Right Answer	RightAnswer::E
Explanation	[[Explanation::Leuprolide is a GnRH analog. If used in pulsatile fashion, it acts as an agonist. If used continuously, it acts as an antagonist, because it downregulates the GnRH receptor in pituitary, therefore decreasing FSH and LH. It is used continuously with flutamide to treat prostatic cancer or uterine fibroids. It is used pulsatile in cases of infertility. Educational Objective: Leuprolide is a GrRH analog, which acts on the pituitary. If used continously it decreases FSH and LH. If used in a pulsatile fashion it increases FSH and LH levels. References: First Aid 2012 for Step 1, Reproductive-Pharmacology chapter. Educational Objective: References: ]]
Approved	Approved::No
Keyword	WBRKeyword::Pituitary hormones
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::