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(Created page with "{{WBRQuestion |QuestionAuthor={{Rim}} |ExamType=USMLE Step 1 |MainCategory=Pharmacology |SubCategory=Musculoskeletal/Rheumatology |MainCategory=Pharmacology |SubCategory=Muscu...")
 
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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{YD}} (Reviewed by {{YD}})
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
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|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
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|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Musculoskeletal/Rheumatology
|SubCategory=Musculoskeletal/Rheumatology
|Prompt=A 45 year old man presents to the physician's office complaining of excruciating left great toe pain. The patient explains that he has been having recurrent episodes of the same pain, each lasting for a few days. Physical examination is remarkable for erythema and tenderness of the first metatarsophalangeal joint. Work-up shows elevated levels of uric acid and elevated C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). The physician prescribes a medication that directly inhibits the conversion of hypoxanthine to xanthine and lacks a purine ring. What is the most likely prescribed medication to treat this patient's condition?
|Prompt=A 55-year-old alcoholic man presents to the physician's office with complaints of excruciating pain in the left great toe. The patient explains that he has been recently having recurrent episodes of the same pain, each episode lasting for a few days. Physical examination is remarkable for erythema and tenderness of the first metatarsophalangeal joint. Work-up is remarkable for elevated blood concentrations of uric acid and C-reactive protein (CRP). The physician prescribes a drug that lacks a purine ring and directly inhibits the conversion of hypoxanthine to xanthine. Which drug has this patient been most likely prescribed?
|Explanation=The patient is presenting with symptoms consistent with gout. The most likely prescribed medication is febuxostat. Febuxostat is a new non-purine xanthine oxidase inhibitor that is considered more potent than allopurinol, which is also a xanthine oxidase inhibitor that contains a purine ring.
|Explanation=The patient is presenting with signs and symptoms consistent with gout. Given his alcohol history, the location and asymmetric nature of the joint pain (left great toe), and elevated concentrations of uric acid and CRP, the diagnosis of gouty attack is very likely. Febuxostat is a new non-purine, xanthine oxidase inhibitor that is more potent than allopurinol. In comparison, allopurinol is a xanthine oxidase inhibitor that contains a purine ring. Xanthine oxidase is an enzyme that metabolizes 2 consecutive reactions in the pathway of uric acid degradation. Xanthine oxidase inhibition results in a reduced rate of hypoxanthine conversion to xanthine and similarly, xanthine conversion to plasma uric acid.
 
Xanthine oxidase is an enzyme required for 2 consecutive steps in the pathway of uric acid degradation. Xanthine oxidase inhibition leads to decreased conversion of hypoxanthine to xanthine and similarly, conversion of xanthine to plasma uric acid.
 
Educational Objective:
Febuxostat is a xanthine oxidase inhibitor that lacks a purine ring, as compared to allopurinol, which also inhibits xanthine oxidase but contains a purine ring.
 
Reference:
Edwards L. Febuxostat: a new treatment for hyperuricaemia in gout. Rheumatology. 2009; 48(2):ii15-ii19.
|AnswerA=Allopurinol
|AnswerA=Allopurinol
|AnswerAExp=Allopurinol is a xanthine oxidase inhibitor that contains a purine ring.
|AnswerAExp=Allopurinol is a xanthine oxidase inhibitor that contains a purine ring.
|AnswerB=Febuxostat
|AnswerB=Febuxostat
|AnswerBExp=Febuxostat is a xanthine oxidase inhibitor that lacks a purine ring.
|AnswerBExp=Febuxostat is a xanthine oxidase inhibitor that lacks a purine ring.
|AnswerC=Probenicid
|AnswerC=Probenecid
|AnswerCExp=Probenicid is a uricosuric that inhibits the reabsorption of uric acid in the proximal convoluted tubule.
|AnswerCExp=Probenecid is a uricosuric that inhibits the reabsorption of uric acid in the proximal convoluted tubule.
|AnswerD=Colchicine
|AnswerD=Colchicine
|AnswerDExp=Colchicine binds and stabilizes tubulin and inhibits polymerization. It impairs chemotaxis and degranulation of leukocytes.
|AnswerDExp=Colchicine binds and stabilizes tubulin and inhibits polymerization. It impairs chemotaxis and degranulation of leukocytes.
|AnswerE=Pegloticase
|AnswerE=Pegloticase
|AnswerEExp=Pegloticase is a pegylated recombinant mammalian uricase that converts urate to allantoin, a more soluble and easily excreted compound.
|AnswerEExp=Pegloticase is a pegylated recombinant mammalian uricase that converts urate to allantoin, a soluble and easily excreted compound.
|EducationalObjectives=Febuxostat is a potent non-purine xanthine oxidase inhibitor indicated for the management of gout.
 
 
|References=Edwards L. Febuxostat: a new treatment for hyperuricaemia in gout. Rheumatology. 2009; 48(2):ii15-ii19.<br>
First Aid 2014 page 441
|RightAnswer=B
|RightAnswer=B
|WBRKeyword=allopurinol, febuxostat, pegloticase, colchicine, probenicid, xanthine, oxidase, inhibitor, inhibitors, inhibition, gout, hyperuricemia, podagra, acute, attack, great, toe
|WBRKeyword=Gout, Gouty attack, Febuxostat, Allopurinol, Purine ring, Alcohol, Pain, MSU, Monosodium urate, Allantoin, Urate, Uric acid, CRP
|Approved=No
|Approved=Yes
}}
}}

Revision as of 21:59, 6 March 2015
Author [[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Yazan Daaboul, M.D.)]]
Exam Type ExamType::USMLE Step 1
Main Category MainCategory::Pharmacology
Sub Category SubCategory::Musculoskeletal/Rheumatology
Prompt [[Prompt::A 55-year-old alcoholic man presents to the physician's office with complaints of excruciating pain in the left great toe. The patient explains that he has been recently having recurrent episodes of the same pain, each episode lasting for a few days. Physical examination is remarkable for erythema and tenderness of the first metatarsophalangeal joint. Work-up is remarkable for elevated blood concentrations of uric acid and C-reactive protein (CRP). The physician prescribes a drug that lacks a purine ring and directly inhibits the conversion of hypoxanthine to xanthine. Which drug has this patient been most likely prescribed?]]
Answer A AnswerA::Allopurinol
Answer A Explanation AnswerAExp::Allopurinol is a xanthine oxidase inhibitor that contains a purine ring.
Answer B AnswerB::Febuxostat
Answer B Explanation AnswerBExp::Febuxostat is a xanthine oxidase inhibitor that lacks a purine ring.
Answer C AnswerC::Probenecid
Answer C Explanation AnswerCExp::Probenecid is a uricosuric that inhibits the reabsorption of uric acid in the proximal convoluted tubule.
Answer D AnswerD::Colchicine
Answer D Explanation AnswerDExp::Colchicine binds and stabilizes tubulin and inhibits polymerization. It impairs chemotaxis and degranulation of leukocytes.
Answer E AnswerE::Pegloticase
Answer E Explanation AnswerEExp::Pegloticase is a pegylated recombinant mammalian uricase that converts urate to allantoin, a soluble and easily excreted compound.
Right Answer RightAnswer::B
Explanation [[Explanation::The patient is presenting with signs and symptoms consistent with gout. Given his alcohol history, the location and asymmetric nature of the joint pain (left great toe), and elevated concentrations of uric acid and CRP, the diagnosis of gouty attack is very likely. Febuxostat is a new non-purine, xanthine oxidase inhibitor that is more potent than allopurinol. In comparison, allopurinol is a xanthine oxidase inhibitor that contains a purine ring. Xanthine oxidase is an enzyme that metabolizes 2 consecutive reactions in the pathway of uric acid degradation. Xanthine oxidase inhibition results in a reduced rate of hypoxanthine conversion to xanthine and similarly, xanthine conversion to plasma uric acid.

Educational Objective: Febuxostat is a potent non-purine xanthine oxidase inhibitor indicated for the management of gout.
References: Edwards L. Febuxostat: a new treatment for hyperuricaemia in gout. Rheumatology. 2009; 48(2):ii15-ii19.
First Aid 2014 page 441]]

Approved Approved::Yes
Keyword WBRKeyword::Gout, WBRKeyword::Gouty attack, WBRKeyword::Febuxostat, WBRKeyword::Allopurinol, WBRKeyword::Purine ring, WBRKeyword::Alcohol, WBRKeyword::Pain, WBRKeyword::MSU, WBRKeyword::Monosodium urate, WBRKeyword::Allantoin, WBRKeyword::Urate, WBRKeyword::Uric acid, WBRKeyword::CRP
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