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Lanoxin toxicity
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- 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.
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- 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
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- 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.
- 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.
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- 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.
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- 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.
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-
Seek
immediate emergency medical
treatment.
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-
Medications
that may increase the Digoxin/Digitalis level
- Verapamil
- Quinidine
- Amiodarone
- Propafenone
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