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.