Digoxin Pharmacology

Digoxin

About Digoxin
A purified cardiac glycoside(((Digitalis Glycoside))), Class IV Antiarrhythmic Agent, Inotropic agent.
Mechanism of Action of Digoxin
Digoxin has positive inotropic effect on heart. It binds to extra cellular face of membrane associated Na+K+ ATPase of myocardial fibres and inhibits this enzyme. Inhibition of this cation pump results in progressive accumulation of Na+ intracellularly. This indirectly results in intracellular Ca2+ accumulation and contraction. The drug increases force and velocity of myocardial contraction, AV node refractory period, total peripheral resistance, and sympathetic outflow (((at higher doses))). It indirectly depresses the SA node and prolongs conduction to the AV node. Increased contractile force improves cardiac out put and systolic emptying and decreases diastolic heart size. It reduces ventricular end diastolic pressure. Reflex reduction of sympathetic tone in heart failure. It reduces elevated heart rate and causes diuresis in edematous conditions. In heart failure it reduces heart size, venous pressure and blood volume.

Pharmacokinets of Digoxin
Absorption: About 60 to 85% of a dose is absorbed orally. Bioavailability increases with capsules.
Distribution: Widely distributed. Metabolism: A smaller portion of drug is metabolized inside the body. Excretion: Most of the drug is excreted unchanged through urine.
Onset of Action for Digoxin
I.V.: 5 to 30 minutes
Oral: 30 to 120 minutes
Duration of Action for Digoxin
3 to 4 days
Half Life of Digoxin
30 to 40 hours
Side Effects of Digoxin
1. Nausea
2. Vomiting
3. Anorexia
4. Abdominal pain
5. Weakness
6. Fatigue
7. Headache
8. Malaise
9. Confusion
10. Restlessness
11. Apnoea
12. Disorientation
13. Psychosis
14. Visual disturbances
15. Abnormal ventricular rhythm
16. Diarrhoea(((rare)))
17. Gynaecomastia (((rare)))

Contra-indications of Digoxin
1. Hypersensitivity to the drug
2. Ventricular fibrillation
3. Ventricular tachycardia
4. Hyper kalaemia
5. Hyper calcaemia
6. Hypertrophic obstructive cardiomyopathy

Special Precautions while taking Digoxin
1. Hepatic impairment
2. Renal impairment
3. Thyrotoxicosis
4. Acute myocardial infarction
5. Partial AV block
6. Premature ventricular contraction
7. Sinus bradycardia
8. Myocarditis
9. Pericarditis
10. Severe pulmonary diseases
Pregnancy Related Information
Use with caution
Old Age Related Information
Use with caution
Breast Feeding Related Information
Use with caution
Children Related Information
May be used
Indications for Digoxin
1. Congestive heart failure
2. Atrial fibrillation
3. Atrial flutter
4. Paroxysmal supraventricular tachycardia

Interactions for Digoxin
Serum digoxin levels are increased by: Amiodarone, Anticholinergics, Benzodiazepines, Captorpril, Esmolol, Flecainide, Hydroxychloroquine, Ibuprofen, Indomethacin, Quinine, Nifedipine, Tolbutamide & Verapamil.
When the following drugs are disocontinued, digoxin toxicity may occur: Aminoglutethimide, Barbiturates, Hydantoin, Phenylbutazone and Rifampicin.
Non-depolarizing muscle relaxants and Succinylcholine: Toxicity of either agent enhanced when used concomitantly.
Pencillamine: Digoxin efficacy decreased.
Spironlactone: It has unpredictable effect.
Amiloride: Inotropic effects of digoxin decreased.
Triamterene: Efficacy of digoxin enhanced.
Thiazide & Loop diuretics: Cause hypokalaemia which enhance efficacy and toxicity of digoxin.
Typical Dosage for Digoxin
Adults:250mcg to 1500mcg/day in two or more divided doses at every 6 to 8 hours.
Maintenance dosage: 250mcg to 500mcg/day.

Children (((age 10 and older))): 10 to 20mcg/kg/day in two or more divided doses at every 6 to 8 hours.
Maintenance dosage: 25 to 35% of total digitalizing dose.
Children (((age 5 to 10))): 20 to 35mcg/kg/day in two or more divided doses at every 6 to 8 hours.
Maintenance dosage: 25 to 35% of total digitalizing dose.
Children (((age 2 to 5))): 30 to 40mcg/kg/day in two or more divided doses at every 6 to 8 hours
Maintenance dosage: 25 to 35% of total digitalizing dose.
Infants (((age 1month to 2years))): 35 to60mcg/kg/day in two or more divided doses at every 6 to 8 hours.
Maintenance dosage: 25 to 35% of total digitalizing dose.

Neonates: 25 to35mcg/kg/day in two or more divided doses at every 6 to 8 hours.
Maintenance dosage: 25 to 35% of total digitalizing dose.
Premature infants: 20 to 30mcg/kg/day in two or more divided doses at every 6 to 8 hour Maintenance dosage: 20 to 30% of total digitalizing dose.

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Schedule of Digoxin
H
Storage Requirements for Digoxin
Store at 15 to 25 degree C. and protects from light.
Effects of Missed Dosage of Digoxin
Take the missed dose as soon as noticed and if it is the time for next dose then skip the missed dose. Continue the regular schedule. Do not double the dose.
Effects of Overdose of Digoxin
Discontinue the drug and induce emesis and gastric lavage to remove the drug from the body. Administer activated charcoal to reduce absorption. Interacting drugs should also be discontinued. Ventricular arrhythmias may be treated with I.V. potassium (((but not in patients with significant AV block))), I.V. phenytoin, I.V. lidocaine, or I.V. propranolol. Refractory ventricular tachyarrhythmias may be controlled with overdrive pacing. Procainamide may be used for ventricular arrhythmias don`t respond to above treatment. Use atropine in severe AV block, asystole, and sinus bradycardia.
Administer Digoxin specific antibody fragments in life threatening Digoxin toxicity. Each 40mg Digoxin specific antibody fragments binds with 0.6mg Digoxin in the blood stream.

Home Delivery for Digoxin in Your City

Medicine India is just a publishing medium for medicine related information and does not provide services or sales of medicines including digoxin.

However, we do publish a comprehensive directory of Pharmacies, Chemists and Druggists in cities all over India. You can use this directory to find the medicine stores in your city (or area) that provide home delivery services for digoxin and other medicines and health products. Home delivery services for digoxin may be free or they may cost you depending on the pharmacy and the minimum order requirements. It would be best to get this clarified while placing the order.

Please be aware that you should take digoxin only if a doctor has recommended or prescribed it. Some or all pharmacies who provide a home delivery service for medicines might insist on a prescription for digoxin before they complete the sale. You can get this information while placing the order for digoxin with the pharmacy.

Digoxin is a generic medicine name and there are several brands available for it. Some of the brands for digoxin might be better known than digoxin itself. If the pharmacy that's willing to deliver medicines to your home doesn't have digoxin in stock, you can ask for one of the branded alternatives for digoxin.