WBR0462: Difference between revisions

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{{WBRQuestion
{{WBRQuestion
|QuestionAuthor={{Rim}}
|QuestionAuthor={{Rim}}, {{AJL}} {{Alison}}
|ExamType=USMLE Step 1
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|MainCategory=Pharmacology
Line 20: Line 20:
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Cardiology
|SubCategory=Cardiology
|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?
|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?
|Explanation=[[Digitalis]] is a direct [[Na/K/ATPase inhibitor]] that indirectly inhibits the [[Na/Ca exchanger]] by inhibiting the Na gradient that essentially plays a role in activating the exchanger.  As a result, intracellular Ca increases and inotropy thus increased.   [[Digitalis]] also has [[cholinomimetic]] effects due to its vagal activation that increases [[PR interval]], delays [[AV node]] conduction, and decreases [[QT interval]].  [[Digitalis]] is commonly used in patients with [[congestive heart failure]]. [[Side effects]] of [[digitalis]] include change in vision color that is typically a green-yellow visual disturbance, as in the patient in the vignette.  
|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:
|EducationalObjectives=
[[Digitalis]] is a positive [[inotropic agent]] that acts as a direct [[Na/K/ATPase inhibitor]] and is used in [[congestive heart failure]].  [[Digitalis]] is associated with green-yellow color changes.
[[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.
|References= First Aid 2014 page 267


|AnswerA=Sildenafil
|AnswerA=Sildenafil
|AnswerAExp=Sildenafil is a phosphodiesterase (PDE) 5 inhibitor that maintains elevated cGMP and nitrous oxide (NO) levels. It is called the “blue pill” because of its color.  Similarly, it causes a blue vision, not a green-yellow visual disturbance.
|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.
|AnswerB=Tadalafil
|AnswerB=Tadalafil
|AnswerBExp=Tadalafil, is a long-acting PDE 5 inhibitor.  Although it might also cause a blue vision similar to sildenafil, it is not classically associated with visual color changes.
|AnswerBExp=[[Tadalafil]], a long-acting PDE 5 inhibitor, is not frequently associated with visual color changes.
|AnswerC=Digitalis
|AnswerC=Digitalis
|AnswerCExp=Digitalis causes a green-yellow color changes as seen in this patient.
|AnswerCExp=See explanation.
|AnswerD=Ethambutol
|AnswerD=Ethambutol
|AnswerDExp=Ethambutol is an anti-tuberculous agent that causes green-red visual changes and optic neuritis, both of which are reversible after discontinuation of the medication. In addition, ethambutol is not given in latent tuberculosis (TB), as in this patient.  It is an antibiotic that is given in active TB.
|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.
|AnswerE=Rifampin
|AnswerE=Rifampin
|AnswerEExp=Rifampin is not associated with visual color changes. It is, however, associated with urine color changes into an orange color that has no clinical significance and self-resolves.  Rifampin is also used in active TB, not latent TB as described in this patient.
|AnswerEExp=[[Rifampin]] is not associated with visual color changes. [[Rifampin]] is not administered in latent tuberculosis (TB), but rather in active TB.
|RightAnswer=C
|RightAnswer=C
|WBRKeyword=digitalis, vision, change, color, disturbance, sildenafil, tadalafiil, ethambutol, side, effect, adverse, drug, reaction
|WBRKeyword=digitalis, vision, sildenafil, tadalafiil, ethambutol, side effect, adverse drug reaction, tuberculosis, medication, optic
|Approved=No
|Approved=Yes
}}
}}

Revision as of 14:45, 24 July 2014
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.
References: First Aid 2014 page 267]]

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::
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