From the FDA Drug Label
Additional doses of 125 to 375 mcg (0. 125 to 0.375 mg) may be given cautiously at 6 to 8-hour intervals until clinical evidence of an adequate effect is noted.
The minimum safe interval between two digoxin doses is 6 to 8 hours 1.
From the Research
The minimum safe interval between two digoxin doses is typically 6 hours. When initiating digoxin therapy or giving additional doses, healthcare providers should wait at least 6 hours between doses to allow for proper drug distribution and to assess the patient's response before administering more medication. This interval is important because digoxin has a narrow therapeutic window, meaning the difference between therapeutic and toxic levels is small. Digoxin works by inhibiting the sodium-potassium ATPase pump in cardiac cells, which increases intracellular calcium and improves cardiac contractility. The drug has a long half-life (approximately 36-48 hours) and can accumulate in the body, so spacing doses appropriately helps prevent toxicity.
Some key points to consider when administering digoxin include:
- Monitoring for signs of digoxin toxicity, including nausea, vomiting, visual disturbances, confusion, and cardiac arrhythmias 2
- Monitoring serum potassium levels, as hypokalemia increases the risk of digoxin toxicity 3
- Adjusting the loading dose for patients with renal dysfunction, as the volume of distribution of digoxin is reduced in these patients 2, 3
- Using a maintenance dose that is appropriate for the patient's renal function, as the clearance of digoxin is reduced in patients with renal impairment 4
In clinical practice, once a maintenance dose is established, digoxin is typically administered once daily. The most recent and highest quality study on this topic is from 2013, which recommends reducing the loading dose of digoxin for patients with creatinine clearance below 60 mL/min 2.
Key factors that influence the minimum safe interval between two digoxin doses include:
- The patient's renal function, as digoxin clearance is reduced in patients with renal impairment 2, 4
- The patient's age, as older patients may be more susceptible to digoxin toxicity 5
- The presence of other medical conditions, such as heart failure or electrolyte imbalances, which can affect digoxin pharmacokinetics and increase the risk of toxicity 2, 3