WBR0509: Difference between revisions
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|SubCategory=Reproductive | |SubCategory=Reproductive | ||
|Prompt=A 61-year-old male comes to the clinic due to hair loss. He has a progressive history of baldness. He has tried many topical ointments and different products seen on TV, which have not been very helpful. He would like to look younger and to prevent losing further hair. The family doctor considers using Finasteride to treat his condition. Which of the following is true about the mechanism of action of this drug? | |Prompt=A 61-year-old male comes to the clinic due to hair loss. He has a progressive history of baldness. He has tried many topical ointments and different products seen on TV, which have not been very helpful. He would like to look younger and to prevent losing further hair. The family doctor considers using Finasteride to treat his condition. Which of the following is true about the mechanism of action of this drug? | ||
|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). | |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). | ||
|AnswerA=It is a non-steroidal competitive inhibitor of androgens at the testosterone receptor | |AnswerA=It is a non-steroidal competitive inhibitor of androgens at the testosterone receptor | ||
|AnswerAExp=<font color="red">'''Incorrect.'''</font> | |AnswerAExp=<font color="red">'''Incorrect.'''</font>This refers to the mechanism of action of [[flutamide]] which is used in [[prostatic carcinoma]]. | ||
|AnswerB=Inhibits the synthesis of steroid | |AnswerB=Inhibits the synthesis of steroid | ||
|AnswerBExp=<font color="red">'''Incorrect.'''</font> | |AnswerBExp=<font color="red">'''Incorrect.'''</font> [[Ketoconazole]] inhibits steroid synthesis by inhibiting desmolase (normally converts cholesterol to [[pregnenolone]]). ACTH stimulates the activity of desmolase. | ||
|AnswerC=Inhibits the conversion of testosterone to DHT | |AnswerC=Inhibits the conversion of testosterone to DHT | ||
|AnswerCExp=<font color="Green">'''Correct.'''</font> It is incorrect because | |AnswerCExp=<font color="Green">'''Correct.'''</font> It is incorrect because | ||
|AnswerD=Inhibits steroid binding | |AnswerD=Inhibits steroid binding | ||
|AnswerDExp=<font color="red">'''Incorrect.'''</font> | |AnswerDExp=<font color="red">'''Incorrect.'''</font> [[ Spironolactone]] inhibits the androgen binding to its receptors. It is a potasium sparing diuretic. [[Flutamide]] and cyproterone also inhibit the androgen-receptor interaction. | ||
|AnswerE=Binds to estrogen receptors | |AnswerE=Binds to estrogen receptors | ||
|AnswerEExp=<font color="red">'''Incorrect.'''</font> | |AnswerEExp=<font color="red">'''Incorrect.'''</font> [[Estrogens]] such as ethinyl estradiol, DES, mestranol bind to estrogen receptors, acting as agonists. Estrogen receptor antagonists include [[tamoxifen]], [[raloxifene]] and [[fulvestrant]]. | ||
|RightAnswer=C | |RightAnswer=C | ||
|WBRKeyword=Testosterone agonist, testosterone antagonist | |WBRKeyword=Testosterone agonist, testosterone antagonist | ||
|Approved=No | |Approved=No | ||
}} | }} | ||
Revision as of 15:32, 25 September 2013
| 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 61-year-old male comes to the clinic due to hair loss. He has a progressive history of baldness. He has tried many topical ointments and different products seen on TV, which have not been very helpful. He would like to look younger and to prevent losing further hair. The family doctor considers using Finasteride to treat his condition. Which of the following is true about the mechanism of action of this drug?]] |
| Answer A | AnswerA::It is a non-steroidal competitive inhibitor of androgens at the testosterone receptor |
| Answer A Explanation | [[AnswerAExp::Incorrect.This refers to the mechanism of action of flutamide which is used in prostatic carcinoma.]] |
| Answer B | AnswerB::Inhibits the synthesis of steroid |
| Answer B Explanation | [[AnswerBExp::Incorrect. Ketoconazole inhibits steroid synthesis by inhibiting desmolase (normally converts cholesterol to pregnenolone). ACTH stimulates the activity of desmolase.]] |
| Answer C | AnswerC::Inhibits the conversion of testosterone to DHT |
| Answer C Explanation | [[AnswerCExp::Correct. It is incorrect because]] |
| Answer D | AnswerD::Inhibits steroid binding |
| Answer D Explanation | [[AnswerDExp::Incorrect. Spironolactone inhibits the androgen binding to its receptors. It is a potasium sparing diuretic. Flutamide and cyproterone also inhibit the androgen-receptor interaction.]] |
| Answer E | AnswerE::Binds to estrogen receptors |
| Answer E Explanation | [[AnswerEExp::Incorrect. Estrogens such as ethinyl estradiol, DES, mestranol bind to estrogen receptors, acting as agonists. Estrogen receptor antagonists include tamoxifen, raloxifene and fulvestrant.]] |
| Right Answer | RightAnswer::C |
| 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: |
| Approved | Approved::No |
| Keyword | WBRKeyword::Testosterone agonist, WBRKeyword::testosterone antagonist |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |