Digoxin Toxicity - USMLE Forums
USMLE Forums Logo
USMLE Forums         Your Reliable USMLE Online Community     Members     Posts
Home
USMLE Articles
USMLE News
USMLE Polls
USMLE Books
USMLE Apps
Go Back   USMLE Forums > USMLE Step 1 Forum

USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 11-26-2010
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 1
Threads: 1
Thanked 5 Times in 1 Post
Reputation: 15
Poison Digoxin Toxicity

Digitalis toxicity

The family of medications derived from the leaves of Digitalis lanata, purpurea, i.e., white and purple foxglove plant-Digitalis, Digoxin, and Lanoxin (trade name) -- is used to treat Heart Failure and supraventricular heart arrythmias (Rapid Heartbeats that originate from the upper heart).
These medications work by paralyzing the Na-K ATPase pump in the contractile cells of the heart. This in turn causes excess Sodium (Na) to accumulate in the cells. To compensate, the Na-Ca pump is activated. This results in an increased level of Calcium in the cells. Calcium is the primary ion involved in contraction. The net result is increased contractility (time to respond to stimuli) of the heart muscle.
Digitalis/Digoxin may cause minor toxic symptoms at twice the effective therapeutic level. It may cause death at five to ten times the effective therapeutic level. As listed below, some conditions may lower the threshold of Digitalis/Digoxin toxicity, while some medications may increase the levels of Digitalis/Digoxin.


Mild toxicity
Nausea/vomiting
Loss of appetite
Vision changes (yellow vision)
Unusual sensations
Heart palpitations/irregularities
Lightheadedness
Fainting
Fatigue
Weight loss
Enlarged male breasts
Mental changes
Cardiac Arrest

Examination:
Heart exam -- may be irregular and/or Slow Heart Rate
EKG may show heart block of all types, premature ventricular beats, bigeminy, ventricular tachycardia, or Ventricular Fibrillation. There is a phenomenon called the "Digoxin effect," which does not represent toxicity, but causes changes to T waves that may occur at therapeutic levels.
Laboratory:
Digoxin level
Potassium, Magnesium, and Calcium levels should be checked -- as should a chemistry panel.
Cardiac enzymes may be checked if there is concern that Myocardial Infarction may have occurred.


Hypokalemia (low Potassium) -- is the most common cause of increased toxicity.
- Patients with Heart Failure are often put on diuretics ("water pills"), which can deplete Potassium.

Myocardial Infarction (heart attack)
Myocardial Ischemia
Hypercalcemia (high Calcium level)
Electrical cardioversion
Hypothyroidism
Hypoxemia (low oxygen levels in blood)
Renal insufficiency
Hypomagnesemia (low Magnesium)
Elderly


Severe toxicity --Digibind, which effectively binds up the Digoxin in the body. It can be lifesaving in severe cases
Ventricular cardiac arrhythmias -- Lidocaine or Phenytoin is given intravenously. Potassium supplementation-cautiously as needed.
Rapid cardiac supraventricular arrhythmias --beta blocker, withdrawal of digoxin, Potassium supplementation cautiously, as needed
Heart block -- Atropine or isoproterenol intravenously, or transcutaneous external cardiac pacemaker. Potassium supplementation should not be employed.


Medications that may increase the Digoxin/Digitalis level
Verapamil
Quinidine
Amiodarone
Propafenone
Reply With Quote Quick reply to this message
The above post was thanked by:
meka (11-27-2010), Noa2013 (05-20-2015), phlebgirl (05-31-2014), rigbbm (04-20-2016), yinn (05-01-2014)



  #2  
Old 11-26-2010
YoramFishke's Avatar
USMLE Forums Veteran
 
Steps History: 1+CK+CS
Posts: 248
Threads: 11
Thanked 307 Times in 127 Posts
Reputation: 337
Default

That's nice
Can you tell us your source !
Reply With Quote Quick reply to this message
  #3  
Old 05-31-2014
USMLE Forums Scout
 
Steps History: Not yet
Posts: 12
Threads: 3
Thanked 5 Times in 3 Posts
Reputation: 15
Default Why does hypokalemia worsen Digoxin toxicity?

Hey all! So I understand Digoxin's MOA and, alongside, why pts on diuretics are at risk for hypokalemia. But I just can't seem to put the two together. Does anyone know why specifically hypokalemia would worsen Digoxin toxicity?

Thank you!
Reply With Quote Quick reply to this message
  #4  
Old 02-27-2015
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 1
Threads: 0
Thanked 0 Times in 0 Posts
Reputation: 10
Default

Quote:
Originally Posted by Ahmed mido View Post
Digitalis toxicity

The family of medications derived from the leaves of Digitalis lanata, purpurea, i.e., white and purple foxglove plant-Digitalis, Digoxin, and Lanoxin (trade name) -- is used to treat Heart Failure and supraventricular heart arrythmias (Rapid Heartbeats that originate from the upper heart).
These medications work by paralyzing the Na-K ATPase pump in the contractile cells of the heart. This in turn causes excess Sodium (Na) to accumulate in the cells. To compensate, the Na-Ca pump is activated. This results in an increased level of Calcium in the cells. Calcium is the primary ion involved in contraction. The net result is increased contractility (time to respond to stimuli) of the heart muscle.
Digitalis/Digoxin may cause minor toxic symptoms at twice the effective therapeutic level. It may cause death at five to ten times the effective therapeutic level. As listed below, some conditions may lower the threshold of Digitalis/Digoxin toxicity, while some medications may increase the levels of Digitalis/Digoxin.


Mild toxicity
Nausea/vomiting
Loss of appetite
Vision changes (yellow vision)
Unusual sensations
Heart palpitations/irregularities
Lightheadedness
Fainting
Fatigue
Weight loss
Enlarged male breasts
Mental changes
Cardiac Arrest

Examination:
Heart exam -- may be irregular and/or Slow Heart Rate
EKG may show heart block of all types, premature ventricular beats, bigeminy, ventricular tachycardia, or Ventricular Fibrillation. There is a phenomenon called the "Digoxin effect," which does not represent toxicity, but causes changes to T waves that may occur at therapeutic levels.
Laboratory:
Digoxin level
Potassium, Magnesium, and Calcium levels should be checked -- as should a chemistry panel.
Cardiac enzymes may be checked if there is concern that Myocardial Infarction may have occurred.


Hypokalemia (low Potassium) -- is the most common cause of increased toxicity.
- Patients with Heart Failure are often put on diuretics ("water pills"), which can deplete Potassium.

Myocardial Infarction (heart attack)
Myocardial Ischemia
Hypercalcemia (high Calcium level)
Electrical cardioversion
Hypothyroidism
Hypoxemia (low oxygen levels in blood)
Renal insufficiency
Hypomagnesemia (low Magnesium)
Elderly


Severe toxicity --Digibind, which effectively binds up the Digoxin in the body. It can be lifesaving in severe cases
Ventricular cardiac arrhythmias -- Lidocaine or Phenytoin is given intravenously. Potassium supplementation-cautiously as needed.
Rapid cardiac supraventricular arrhythmias --beta blocker, withdrawal of digoxin, Potassium supplementation cautiously, as needed
Heart block -- Atropine or isoproterenol intravenously, or transcutaneous external cardiac pacemaker. Potassium supplementation should not be employed.


Medications that may increase the Digoxin/Digitalis level
Verapamil
Quinidine
Amiodarone
Propafenone
The inactivation of Na-K ATPase increases the intracellular conc. of Na. This in turn inhibits(not activates) the 3Na-Ca exchanger which leads to increased intracellular conc. of Ca and the subsequent ionotropy......
Reply With Quote Quick reply to this message
  #5  
Old 06-24-2016
USMLE Forums Newbie
 
Steps History: Not yet
Posts: 8
Threads: 0
Thanked 0 Times in 0 Posts
Reputation: 10
Default

digitalis can cause almost any cardiac arrhythmia except mobitz type 2 block and atrial flutter


most characteristic arrhythmia due to its toxicity is non paroxysomal SVT with av block

MC is premature beats and V bigeminy
Reply With Quote Quick reply to this message
  #6  
Old 06-25-2016
USMLE Forums Scout
 
Steps History: Not yet
Posts: 84
Threads: 1
Thanked 49 Times in 35 Posts
Reputation: 59
Default

Quote:
Originally Posted by phlebgirl View Post
Hey all! So I understand Digoxin's MOA and, alongside, why pts on diuretics are at risk for hypokalemia. But I just can't seem to put the two together. Does anyone know why specifically hypokalemia would worsen Digoxin toxicity?

Thank you!
Digoxin binds to the potassium site on the Na/K pump, in other words digoxin and potassium are competing for the same binding site. Less potassium, less competition for digoxin, more digoxin bound to the Na/K pump, more effect.
Reply With Quote Quick reply to this message
The above post was thanked by:
drdeep (07-26-2016)



Reply

Tags
Pharmacology-, Toxicology-

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the USMLE Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.
User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Medical School
Choose "---" if you don't want to tell. AMG for US & Canadian medical schools. IMG for all other medical schools.
USMLE Steps History
What steps finished! Example: 1+CK+CS+3 = Passed Step 1, Step 2 CK, Step 2 CS, and Step 3.

Choose "---" if you don't want to tell.

Favorite USMLE Books
What USMLE books you really think are useful. Leave blank if you don't want to tell.
Location
Where you live. Leave blank if you don't want to tell.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes


Similar Threads
Thread Thread Starter Forum Replies Last Post
Aspirin Toxicity Symptoms step1an USMLE Step 1 Forum 7 08-22-2010 01:18 PM
Prevent Toxicity in Birth silakan_isi USMLE Step 1 Forum 1 06-04-2010 07:34 PM
TCA toxicity abhinav USMLE Step 1 Forum 2 03-27-2010 05:38 PM
After Party Toxicity Yallah USMLE Step 1 Forum 3 03-24-2010 01:07 AM
Vitamin C toxicity and Kidney Stones! lemontea88 USMLE Step 1 Forum 10 12-21-2009 11:04 PM

RSS Feed
Find Us on Facebook
vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.

USMLE® & other trade marks belong to their respective owners, read full disclaimer
USMLE Forums created under Creative Commons 3.0 License. (2009-2014)