(digoxin)
Brands
Digoxin, Lanoxin
Availability
- Tablets: 0.125 mg, 0.25 mg, 0.5 mg
- Capsules: 0.05 mg, 0.1 mg, 0.2 mg
- Pediatric Elixir: 0.05 mg/mL via dropper
- Injectable: 0.1 mg/mL, 0.25 mg/mL
Pharmacology
A cardiac glycoside, digoxin’s positive inotropic effects promotes movement of calcium from extracellular to intracellular cytoplasm, and inhibits sodium-potassium activated adenosine triphosphatase which increases myocardial contractility and output. It is able to increase diuresis, reduce edema, reduce heart rate, and blood volume. It is also able to reduce pulmonary congestion and venous pressure.
It is absorbed in the small intestine, distributed widely in tissues with the highest levels being in kidneys, heart, intestine, stomach, liver and skeletal muscle. The drug is only slightly metabolized, and is excreted by way of glomerular and tubular secretion.
Studies have not determined safety of giving the drug in pregnant or lactating animals.
Indications
Used in CHF due to venous congestion, arrhythmias, and dilated cardiomyopathy.
Drug Interactions or Contraindications
- Not recommended to be mixed in with other medications.
- Use cautiously in glomerulonephritis and severe pulmonary disease.
- The following drugs may decrease digoxin’s absorption: antacids, cimetidine, metoclopramide, neomycin, and some chemotherapy agents.
- Digoxin serum levels may increase or its elimination rate decreased, or toxic effects enhanced with the following drugs (see Considerations):
- diazepam
- quinidine
- anticholinergics
- succinylcholine
- verapamil
- tetracyclines
- erythromycin
- furosemide
- thiazides
- glucocorticoids
- laxatives.
For additional information regarding interactions check with a Pharmacist.
Adverse Reactions
*Toxicity: Narrow margin of safety. Overdosage is a cumulative effect. The most serious of which is low potassium level (hypokalemia).
CNS: irritability, lethargy
CV: changes in heart rate, rhythm, irritability of the heart and mechanics of the heart.
GI: decreased appetite, abdominal pain, diarrhea, bowel necrosis.
Dosage Recommendations
0.0025 mg/lb, PO, BID 3, 12
or
0.005 mg/kg to 0.01 mg/kg, PO, q12hr to q24hr 35, 41, 44
*Note: smaller dosages should be used in animals with hyponatremia (low sodium), hypokalemia (low potassium), hypercalcemia (high calcium), and hypo or hyperthyroidism.
Considerations
- May be used in combined treatment with a diuretic (e.g., Lasix), and / or ACE inhibitors as deemed appropriate by a veterinarian, and where benefit outweighs risk.
- Food may delay the drugs absorption but does not alter it.
- Store at room temperature, away from light.
