WBR0462
| 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::Cardiology |
| Prompt | [[Prompt::A 62-year-old male presents to the physician’s office with complaints of abnormal vision. The patient explains that he has been seeing yellow-green halos beginning upon the administration of a new drug. The patient’s past medical history is significant for latent tuberculosis, cardiac disease, and erectile dysfunction. Which of the following medications is most likely the cause of this patient’s symptoms?]] |
| Answer A | AnswerA::Sildenafil |
| Answer A Explanation | [[AnswerAExp::Sildenafil, a phosphodiesterase (PDE) 5 inhibitor, maintains elevated cGMP and nitrous oxide (NO) levels. It frequently manifests with blue colored vision, rather than a green-yellow visual disturbance.]] |
| Answer B | AnswerB::Tadalafil |
| Answer B Explanation | [[AnswerBExp::Tadalafil, a long-acting PDE 5 inhibitor, is not frequently associated with visual color changes.]] |
| Answer C | AnswerC::Digitalis |
| Answer C Explanation | AnswerCExp::See explanation. |
| Answer D | AnswerD::Ethambutol |
| Answer D Explanation | [[AnswerDExp::Ethambutol, an anti-tuberculous agent, frequently causes green-red visual changes and optic neuritis, both of which are reversible following discontinuation of the medication. Ethambutol is not administered in latent tuberculosis (TB), but rather in active TB.]] |
| Answer E | AnswerE::Rifampin |
| Answer E Explanation | [[AnswerEExp::Rifampin is not associated with visual color changes. Rifampin is not administered in latent tuberculosis (TB), but rather in active TB.]] |
| Right Answer | RightAnswer::C |
| Explanation | [[Explanation::Digitalis, a direct Na/K/ATPase inhibitor, inhibits the Na/Ca exchanger by hindering the creation of a sodium gradient. This results in increased inotropy by augmenting levels of intracellular Ca. Digitalis has cholinomimetic effects, due to its vagal activation, by increasing the PR interval, delaying AV node conduction, and decreasing the QT interval. Digitalis is frequently administered to patients with congestive heart failure. The side effects of digitalis include a change in vision coloration, typically manifesting as a green-yellow visual disturbance. Educational Objective: Digitalis, a positive inotropic agent, acts as a direct Na/K/ATPase inhibitor and is administered to patients with congestive heart failure. Digitalis is associated with green-yellow color changes. |
| Approved | Approved::Yes |
| Keyword | WBRKeyword::digitalis, WBRKeyword::vision, WBRKeyword::sildenafil, WBRKeyword::tadalafiil, WBRKeyword::ethambutol, WBRKeyword::side effect, WBRKeyword::adverse drug reaction, WBRKeyword::tuberculosis, WBRKeyword::medication, WBRKeyword::optic |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |