Digoxin toxicity can occur due to various predisposing factors and causes that increase digoxin levels like drug interactions and electrolyte imbalances. Manifestations include cardiac, gastrointestinal, neurological and other symptoms. Diagnosis involves evaluating symptoms, past digoxin use, ECG changes, electrolyte and renal status, and plasma digoxin levels. Treatment focuses on stopping digoxin, decreasing absorption, correcting electrolyte imbalances, and using medications like potassium, beta blockers, antiarrhythmics or digoxin antibodies in severe cases.

1. DIGOXIN TOXICITY
By Dr.VIJAY
Department of Pharmacology

2. DIGOXIN
 SOURCE:
 STRUCTURE:
 MECHANISM OF ACTION:

5. DIGOXIN TOXICITY
PREDISPOSING FACTORS:
 Age
 Hypokalemia
 Hypercalcemia
 Impaired renal function
 Cor pulmonale
 Cardiac status
 Hormones
 Inappropriate use
CAUSES :

6.  Drug interactions causing increase in digoxin
levels:
 Hypokalemia:
 Calcium salts:
 Drugs which displace digoxin from
protien binding sites:
 Catecholamines,Sch:

7. Manifestations of Toxicity
 CARDIAC TOXICITY:
Most common manifestation:
PAROXYSMAL ATRIAL
TACHYCARDIA WITH BLOCK
Others: Multifocal extrasystoles & bigeminy
AV block
Sinoatrial arrest
VT and VF

8.  GASTROINTESTINAL TOXICITY:
 NEUROLOGICAL TOXICITY:
 MISCELLANEOUS TOXICITY:skin
rash,eosinophilia,gynecomastia.
 TOXICITY in Pregnancy:

9. DIFFERENTIAL DIAGNOSIS
 CHF and Pulmonary edema
 Heart Block
 Beta blocker toxicity
 VT and VF
 Low K and high K level
 Low Mg and high Ca levels.

10. DIAGNOSIS
 Symptoms and signs:
 Past h/o digitalization:
 ECG:
 Electrolyte and Renal status:
 Plasma digoxin level:0.5-2ng/ml:
After acute ingestion digoxin level do not
necessarily correlate with toxicity.
T1/2 of digoxin is reduced to 10-12hrs after
acute ingestion.

11.  Plasma digoxin levels should be
measured at least 6 hours after the last
dose, since this is the time required for
attainment of the steady state.
 An extremely rapid radioimmunoassay for digoxin
on the use of iodine 125-labelled digoxin and of a gel
equilibration technique for the separation of antibody-
bound and free digoxin.
 Endogenous Digoxin Like
Immunoreactive Substances {DLIS}
seen in neonates,renal insufficiency,liver
disease,SAH,CHF,diabetes.

12. TREATMENT OF TOXICITY
 Stop digoxin and diuretics:
 GIT decontamination:
 Decreasing absorption:
 Estimate serum potassium:
 Bradycardia:
 Mild toxicity:
Potassium salts:5-7.5g of KCl
Serious arrhythmias:40mEq of KCl in 500ml
of 5% glucose IV OVER 2-4 hrs.
C/I to use of potassium:

13.  Supraventricular tachyarrhythmias:
Propranolol :oral dose of 10-40mg every
6hrs /IV .5-1-1mg.
 Ventricular tachycardia:
Lignocaine:1-2mg /kg IV repeat in 20-
30mins.
Phenytoin: IV:250mg well diluted over 3-
5min.

14.  Severe toxicity:DIGIBIND
Antidigoxin antibodies:
Source:
MOA:
Molecular weight:
T1/2:
Indications:
Life threatening arrhythmias
Hemodynamic instability
Severe bradycardia
Serum potassium level:
Plasma digoxin level:
Time taken for complete response:

15.  Dosing of Digibind:
Vials of digibind=digoxin level[ng/ml]x wt[kg]
100
1Vial of Digibind=40mg
= neutralizes 0.6mg of digoxin.

16.  Side effects of Digibind:
Allergic reactions
Exacerbation of CHF
Hypokalemia
Plasma digoxin level unreliable
after digibind is given.
Increased ventricular response
to atrial fibrillation and flutter.
 CONTRAINDICATIONS:Allergic to sheep
protien, papain, papaya extracts.