WBR0510: Difference between revisions

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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor=[[User:Gonzalo Romero|Gonzalo A. Romero, M.D.]] [mailto:gromero@wikidoc.org]
|QuestionAuthor=[[User:Gonzalo Romero|Gonzalo A. Romero, M.D.]] [mailto:gromero@wikidoc.org] (Reviewed by Will Gibson)
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
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|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
|SubCategory=Endocrine, Reproductive
|SubCategory=Endocrine, Reproductive
|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
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|MainCategory=Pharmacology, Physiology
|MainCategory=Pharmacology, Physiology
|SubCategory=Endocrine, Reproductive
|SubCategory=Endocrine, Reproductive
|Prompt=A pharmacist 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”?
|Prompt=A pharmacist is planning a study with mice in order to determine the effects of a novel drug called “Compound A572”. He knows that the drug is supposed to work in the hypothalamus, to regulate the release of different pituitary hormones.  He measures serum concentration of hypothalamic hormones and determines that the drug causes different changes in FSH and LH if dosed continuously or in a pulsatile fashion. Which of the following drugs has a similar mechanism of action as “Compound A572”?
|Explanation=[[Leuprolide]] is a [[GnRH ]] analog. If used in pulsatile fashion, it acts as an agonist, while if used continuously, it acts as an antagonist, because it downregulates the GnRH receptor in pituitary, therefore decreasing [[FSH]] and [[LH]]. It is often used continuously with flutamide to treat prostatic cancer or uterine fibroids.  [[Leuprolide]] is often used pulsatile in cases of infertility.
|Explanation=[[Leuprolide]] is a [[GnRH ]] analogue. If used in pulsatile fashion, it acts as an agonist, while if used continuously, it acts as an antagonist. Continuous dosing of the drug causes the posterior pituitary to downregulate GnRH receptors due to negative feedback. The posterior pituitary thereby decreases the production of [[FSH]] and [[LH]]. Recall that FSH and LH are responsible for stimulating the release of sex hormones in both men and women. Leuprolide therefore has important therapeutic roles in diseases associated with the activity of sex hormones.
|EducationalObjectives=
 
# Leuprolide is a GrRH analog, which acts on the pituitary.
It is often used continuously with flutamide to treat prostatic cancer or uterine fibroids.  [[Leuprolide]] is often used pulsatile in cases of infertility.
# If used continously it decreases FSH and LH.  If used in a pulsatile fashion it increases FSH and LH levels.
[[File:Pituitary Phys.png|center|400px]]<br>
|References=
First Aid 2012 for Step 1, Reproductive-Pharmacology chapter.
|AnswerA=Flutamide
|AnswerA=Flutamide
|AnswerAExp=[[Flutamide]] is a nonsteroidal competitive inhibitor of androgens at the testosterone receptor used in [[prostate cancer]].
|AnswerAExp=[[Flutamide]] is a nonsteroidal competitive inhibitor of androgens at the androgen receptor. It is used to treat [[prostate cancer]] and hyperandrogenism in polycystic ovarian syndrome.
|AnswerB=Finasteride
|AnswerB=Finasteride
|AnswerBExp=[[Finasteride]] is a 5 alfa-reductase inhibitor used to treat BPH and male-pattern baldness.
|AnswerBExp=[[Finasteride]] is a 5 alpha-reductase inhibitor used to treat benign prostatic hyperplasia and male-pattern baldness.
|AnswerC=Mifepristone
|AnswerC=Mifepristone
|AnswerCExp= [[Mifepristone]] is a competitive inhibitor of progestins at the [[progesterone]] receptors. It is used to terminate [[pregnancy]] in combination with [[misoprostol]] (PGE1 analog).
|AnswerCExp=[[Mifepristone]] is a competitive inhibitor of progestins at the [[progesterone]] receptors. It is used to terminate [[pregnancy]] in combination with [[misoprostol]] (PGE1 analogue).
|AnswerD=Ketoconazol
|AnswerD=Ketoconazole
|AnswerDExp= [[Ketoconazol]] is a steroid synthesis inhibitor by inhibiting desmolase, which transforms [[cholesterol]] into [[pregnenolone]].
|AnswerDExp=[[Ketoconazole]] is a steroid synthesis inhibitor that inhibits desmolase, the enzyme responsible for transforming [[cholesterol]] into [[pregnenolone]].
|AnswerE=Leuprolide
|AnswerE=Leuprolide
|AnswerEExp=See overall explanation.
|AnswerEExp=Leuprolide is a GnRH analogue
|EducationalObjectives=# Leuprolide is a GrRH analogue, 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 2014 page 590
|RightAnswer=E
|RightAnswer=E
|WBRKeyword=Pituitary hormones
|WBRKeyword=Pituitary hormones, Pituitary
|Approved=No
|Approved=No
}}
}}

Revision as of 13:34, 10 January 2015
Author [[PageAuthor::Gonzalo A. Romero, M.D. [1] (Reviewed by Will Gibson)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pharmacology, MainCategory::Physiology
Sub Category SubCategory::Endocrine, SubCategory::Reproductive
Prompt [[Prompt::A pharmacist is planning a study with mice in order to determine the effects of a novel drug called “Compound A572”. He knows that the drug is supposed to work in the hypothalamus, to regulate the release of different pituitary hormones. He measures serum concentration of hypothalamic hormones and determines that the drug causes different changes in FSH and LH if dosed continuously or in a pulsatile fashion. Which of the following drugs has a similar mechanism of action as “Compound A572”?]]
Answer A AnswerA::Flutamide
Answer A Explanation [[AnswerAExp::Flutamide is a nonsteroidal competitive inhibitor of androgens at the androgen receptor. It is used to treat prostate cancer and hyperandrogenism in polycystic ovarian syndrome.]]
Answer B AnswerB::Finasteride
Answer B Explanation [[AnswerBExp::Finasteride is a 5 alpha-reductase inhibitor used to treat benign prostatic hyperplasia and male-pattern baldness.]]
Answer C AnswerC::Mifepristone
Answer C Explanation [[AnswerCExp::Mifepristone is a competitive inhibitor of progestins at the progesterone receptors. It is used to terminate pregnancy in combination with misoprostol (PGE1 analogue).]]
Answer D AnswerD::Ketoconazole
Answer D Explanation [[AnswerDExp::Ketoconazole is a steroid synthesis inhibitor that inhibits desmolase, the enzyme responsible for transforming cholesterol into pregnenolone.]]
Answer E AnswerE::Leuprolide
Answer E Explanation AnswerEExp::Leuprolide is a GnRH analogue
Right Answer RightAnswer::E
Explanation [[Explanation::Leuprolide is a GnRH analogue. If used in pulsatile fashion, it acts as an agonist, while if used continuously, it acts as an antagonist. Continuous dosing of the drug causes the posterior pituitary to downregulate GnRH receptors due to negative feedback. The posterior pituitary thereby decreases the production of FSH and LH. Recall that FSH and LH are responsible for stimulating the release of sex hormones in both men and women. Leuprolide therefore has important therapeutic roles in diseases associated with the activity of sex hormones.

It is often used continuously with flutamide to treat prostatic cancer or uterine fibroids. Leuprolide is often used pulsatile in cases of infertility.
Educational Objective: # Leuprolide is a GrRH analogue, which acts on the pituitary.

  1. If used continously it decreases FSH and LH. If used in a pulsatile fashion it increases FSH and LH levels.

References: First Aid 2014 page 590]]

Approved Approved::No
Keyword WBRKeyword::Pituitary hormones, WBRKeyword::Pituitary
Linked Question Linked::
Order in Linked Questions LinkedOrder::
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