WBR0413
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Pharmacology |
| Sub Category | SubCategory::Renal |
| Prompt | [[Prompt::A 72-year-old male presents to your office with dyspnea and bilateral pitting edema. His medical history is significant for diabetes mellitus, gout, and osteoarthritis. Upon further questioning, the patient tells you he cannot tolerate several medications because he is allergic. He recalls that he developed a skin rash when he used sulfonylurea, probenicid, celecoxib, and sulfonamide antibiotics. Nonetheless, you decide to prescribe him a diuretic to relieve his symptoms. Which of the following diuretics is the best option for this patient?]] |
| Answer A | AnswerA::Furosemide |
| Answer A Explanation | [[AnswerAExp::Furosemide, a loop diuretic, commonly causes sulfa allergy.]] |
| Answer B | AnswerB::Acetazolamide |
| Answer B Explanation | [[AnswerBExp::Acetazolamide, a carbonic anhydrase inhibitor, commonly causes sulfa allergy.]] |
| Answer C | AnswerC::Ethacrynic acid |
| Answer C Explanation | [[AnswerCExp::Ethacrynic acid is a diuretic often prescribed to patients with sulfa allergy.]] |
| Answer D | AnswerD::Hydrochlorothiazide |
| Answer D Explanation | [[AnswerDExp::Hydrochlorothiazide is a thiazides-type diuretic. Thiazides are associated with sulfa allergy.]] |
| Answer E | AnswerE::Chlorthalidone |
| Answer E Explanation | [[AnswerEExp::Chlorthalidone is also a thiazides-type diuretic. Thiazides are associated with sulfa allergy.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Sulfa allergy is a term that describes adverse drug reactions to a list of several medications. Sulfa allergy is typically seen in the following medications: Sulfonamide, sulfasalazine, sulfonylurea, celecoxib, probenicid, and diuretics such as furosemide, acetazolamide, and thiazides-type diuretics.
Sulfa allergy has an incidence rate of less than 5% among the general population. It has a range of manifestations from very mild to fatal. Symptoms include skin rash, hepatic, renal, and pulmonary injury, and hematologic disturbances, such as thrombocytopenia, leucopenia, and hemolytic anemia. Treatment of sulfa allergy includes stopping the offending medications and symptomatic treatment of its manifestations until resolution.
In patients who require dieresis, ethacrynic acid, a phenoxyacetic acid derivative, is a loop diuretic that is not associated with sulfa allergy. Because it is frequently associated with ototoxicity, it is usually only reserved for patients who are known to have sulfa allergy. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::Sulfa drug allergy, WBRKeyword::diuretics, WBRKeyword::ethacrynic acid |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |