Digoxin

About Digoxin

1. DIGOXIN
Dr. Amlendra
Phase-A Resident
(BSMMU)

2. About Digoxin
•It is a purified cardiac glycoside extracted
from the foxglove plant, Digitalis lanata.
•Its corresponding aglycone is digoxigenin,
and its acetyl derivative is acetyldigoxin
•It is widely used in the treatment of various
heart conditions namely atrial fibrillation,
atrial flutter and sometimes heart failure
that cannot be controlled by other
medication

3. Pharmacological Class :- Cardiac Glycoside
Therapeutic Class :- Inotrope, antiarrhythmic

4. Action
•The main pharmacological effects of digoxin are
on the heart
•It has mechanical effects as it increases
myocardial contractility; however, the duration of
the contractile response is just slightly increased
•Overall, the heart rate is decreased, while blood
pressure increases as the stroke volume is
increased, leading to increased tissue perfusion
•Myocardial efficiency is due to improved
hemodynamics, and the ventricular function
curve is improved.

5. Cont..
•Other, electrical effects are an initial brief
increase in action potential, followed by a
decrease as the K+ conductance increases due
to an increased intracellular amounts of Ca2+
ions
•The refractory period of the atria and ventricles
is decreased, while it increases in the sinoatrial
and AV nodes
•A less negative resting membrane potential is
made, leading to increased excitability

6. Cont..
•Slight vasodilation is seen in heart failure. This
effect is contrary to effects that should be seen
as a result of increased intracellular calcium
levels, but this occurs since digoxin improves
hemodynamics, which leads to restored
angiotensin levels and decreased sympathetic
discharge, causing indirect vasodilation.
•It also affects the kidney by increased renal
blood flow and increased glomerular filtration
rate. A mild diuretic effect is seen only in heart
failure .

7. Pharmacokinetics
•About 70 to 80% of an oral dose of digoxin is
absorbed, mainly in the proximal part of the
small intestine. The degree of binding to serum
albumin is 20 to 30%. Digoxin is extensively
distributed in the tissues, as reflected by the
large volume of distribution. High concentrations
are found in the heart and kidneys, but the
skeletal muscles form the largest digoxin
storage.
•The half-life of elimination varies between 26
and 45 hours

8. Cont..
•The main route of elimination is renal excretion of
digoxin, which is closely correlated with the glomerular
filtration rate. In addition, some tubular secretion and
perhaps tubular reabsorption occurs. Nearly all of the
digoxin in the urine is excreted unchanged, with a small
part as active metabolites. The clinical significance of
dihydrodigoxin as a metabolite remains to be resolved.
About 25 to 28% of digoxin is eliminated by nonrenal
routes. Biliary excretion may rise up to 30% of a given
dose, but the enterohepatic cycle seems to be of minor
importance.

9. Indication
•Heart Failure
•Tachyarrhythmias
•Atrial Fibrillation
•Atrial Flutter
•Paroximal atrial tachycardia

10. Dosing

11. Administration
•Administer slowly by direct IV injection
over minimum of 5 minutes (longer if given
undiluted)
•Do not administer if precipitate present
•Drug is severe skin irritant when given
IV/IM and may cause severe local skin
reaction with possible sloughing

12. Contraindication and Precaution
•Hypersensitivity
•Uncontrolled Ventricular Arrhythmias
•AV block
•Constrictive Pericarditis
•Idiopathic Hypertrophic Subaortic Stenosis

13. Use cautiously in
•Renal & Hepatic impairment
•Electrolyte imbalance
•Myocardial Infarction
•Thyroid Disoder
•Obesity
•Elderly Patient
•Pregnancy
•Breastfeeding infant

14. Adverse Effects
•Dizziness (4.9%)
•Mental disturbances (4.1%)
•Diarrhea (3.2%)
•Headache (3.2%)
•Nausea (3.2%)
•Vomiting (1.6%)
•Maculopapular rash (1.6%)

15. <1%
•Anorexia
•Cardiac dysrhythmia
•Arrhythmia in children (consider a toxicity)