From the Guidelines
Digoxin does not directly affect blood pressure, but it may have an indirect effect by improving cardiac output in heart failure patients. The primary mechanism of action of digoxin is to inhibit the sodium-potassium pump in cardiac cells, which increases intracellular calcium and strengthens heart contractions, thereby affecting heart rate and contractility rather than directly impacting blood pressure 1. While digoxin can indirectly influence blood pressure by improving cardiac output in heart failure patients, it is not considered a blood pressure medication.
- Key points to consider when prescribing digoxin include:
- The medication is primarily prescribed for heart rate control in atrial fibrillation and for improving symptoms in heart failure, usually at doses of 0.125-0.25 mg daily 1.
- Low doses (0.125 mg daily or every other day) should be used initially if the patient is >70 years of age, has impaired renal function, or has a low lean body mass 1.
- Blood pressure should be monitored during digoxin therapy, but adjustments to blood pressure medications would generally be made independently of digoxin dosing.
- It is essential to note that significant blood pressure changes are not typically expected with digoxin therapy, and the medication's primary benefits are related to its effects on heart rate and contractility, rather than blood pressure control 1.
From the Research
Effects of Digoxin on Blood Pressure
- Digoxin has been found to have varying effects on blood pressure, with some studies indicating a decrease in diastolic blood pressure and others showing no significant effect 2, 3.
- In healthy volunteers, 10 days of oral digoxin caused decreases in diastolic blood pressure and heart rate during overnight sleep, but no effect was detectable during daytime activities 2.
- In patients with heart failure, digoxin has been shown to cause a decrease in diastolic blood pressure, but the effect on systolic blood pressure is less clear 2, 4.
- The pressor and vascular effects of cardiac glycosides, including digoxin, have been found to be contradictory, with some studies showing increased, decreased, or unaltered blood pressure values following administration 3.
Mechanisms of Action
- The mechanisms by which digoxin affects blood pressure are not fully understood, but may involve changes in sympatho-vagal balance and central neurohumoral effects 2, 3.
- Digoxin has been found to reduce circulating norepinephrine levels and increase atrial natriuretic peptide levels, which may contribute to its effects on blood pressure 4.
- The local effects of systemic digoxin on the cutaneous microcirculation have been found to include reduced resting heart rate, blood pressure, and baseline cutaneous blood flow, as well as augmented vasoconstrictive effect of exogenous norepinephrine 5.
Clinical Implications
- The effects of digoxin on blood pressure may have therapeutic implications, particularly in patients with heart failure 2, 4.
- The use of digoxin in patients with pulmonary hypertension and right ventricular failure may be warranted, as it has been shown to produce a modest increase in cardiac output and a significant reduction in circulating norepinephrine 4.
- Further studies are needed to fully understand the effects of digoxin on blood pressure and to determine its optimal dosage and clinical use 6.