WBR0478
| Author | [[PageAuthor::Rim Halaby, M.D. [1], Alison Leibowitz [2] (Reviewed by Alison Leibowitz)]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Microbiology, MainCategory::Pharmacology |
| Sub Category | SubCategory::Dermatology |
| Prompt | [[Prompt::A 42-year-old female presents to the dermatology clinic with complaints of a nail lesion. Upon diagnosis of onychomycosis she is prescribed an antimicrobial medication that is then promptly stopped due to alteration of liver function tests and taste disturbance. Which of the following is the mechanism of action that best describes the medication prescribed?]] |
| Answer A | AnswerA::Inhibits squalene epoxidase |
| Answer A Explanation | AnswerAExp::See explanation. |
| Answer B | AnswerB::Inhibits DNA polymerase |
| Answer B Explanation | AnswerBExp::Several antiviral medications, which are not used to treat onychomycosis, inhibit DNA polymerase. |
| Answer C | AnswerC::Inhibits aminoacyl-tRNA attachment |
| Answer C Explanation | AnswerCExp::Tetracyclines, which are not used to treat onychomycosis, inhibit aminoacyl-tRNA attachment. |
| Answer D | AnswerD::Inhibits synthesis of beta-glucan |
| Answer D Explanation | AnswerDExp::Caspofungin, which is not used to treat onychomycosis, inhibits synthesis of beta-glucan. |
| Answer E | AnswerE::Inhibits ergosterol synthesis |
| Answer E Explanation | AnswerEExp::Azoles, which are not used to treat onychomycosis, inhibit ergosterol synthesis. |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::Terbinafine, considered a first line treatment for onychomycosis, is an anti-fungal medication that inhibits squalene epoxidase. The most frequently occurring side effects of Terbinafine] are altered liver function tests (LFTs), GI upset, and taste disturbances. During treatment with terbinafine, patients are requested to routinely perform LFT testing to monitor to drug-induced liver injury (DILI). Educational Objective: Terbinafine, considered a first line treatment for onychomycosis, is an anti-fungal medication that inhibits squalene epoxidase.
The most frequently occurring side effects of Terbinafine are altered liver function tests (LFTs), gastrointestinal disturbances, and taste disturbances. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::terbinafine, WBRKeyword::drug induced liver injury, WBRKeyword::DILI, WBRKeyword::adverse reaction, WBRKeyword::side effect, WBRKeyword::adverse drug reaction, WBRKeyword::antifungal, WBRKeyword::onychomycosis, WBRKeyword::liver function test, WBRKeyword::LFT, WBRKeyword::dermatology, WBRKeyword::digestive system, WBRKeyword::fungus |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |