A Century-Old, 10-Cent Heart Drug Cut Hospitalizations by a Quarter in New Trial

One of medicine’s oldest and cheapest heart drugs has delivered a striking result in a modern clinical trial: low-dose digoxin cut hospitalisations for heart failure by roughly a quarter.

In a trial led by researchers at the University Medical Center Groningen, patients given low-dose digoxin had about 25% fewer heart-failure hospitalisations than those on placebo. Results were published in Nature Medicine and presented alongside a report in JAMA.

A drug with two centuries of history

Digoxin derives from the foxglove plant and has been used for more than two hundred years — its introduction into medicine is usually dated to an eighteenth-century description of a folk remedy for dropsy, the fluid accumulation now recognised as heart failure.

It works by increasing the force of heart muscle contraction and slowing conduction through the heart, and it costs less than 10 cents a day.

Why it fell out of favour

Digoxin was standard heart-failure therapy for decades and was progressively displaced — partly by newer drugs with mortality benefit, and partly by a genuine problem with the drug itself.

Digoxin has a narrow therapeutic window: the difference between an effective dose and a toxic one is small. Toxicity causes nausea, visual disturbance, confusion and dangerous heart rhythm abnormalities, and the risk rises with kidney impairment and with the electrolyte disturbances common in heart-failure patients on diuretics.

A large trial in the 1990s found digoxin reduced hospitalisations without improving survival, and as drugs with demonstrated mortality benefit accumulated, digoxin was relegated to an add-on for patients who remained symptomatic.

What the low-dose approach changes

The low-dose approach tested here reflects lessons from decades of experience, and this is the key design decision.

Analyses of earlier data suggested the benefit and the harm separate by dose — that lower serum concentrations retained the reduction in hospitalisations while higher concentrations drove the toxicity and the absence of survival benefit. Historical dosing frequently produced levels toward the upper end.

Testing a deliberately low dose is therefore an attempt to isolate the useful part of the drug from the dangerous part, informed by why the original trials looked the way they did.

The trial

The study enrolled roughly 1,000 patients across 43 centres in the Netherlands and followed them for about three years, comparing low-dose digoxin against placebo on top of standard heart-failure therapy.

That last point matters. Modern heart-failure care involves several drug classes with proven mortality benefit, so the question is not whether digoxin beats nothing but whether it adds anything to contemporary treatment — a considerably harder test than the one it faced in the 1990s.

The results, read carefully

Beyond fewer hospital admissions, investigators reported a 19% reduction in a combined measure of cardiovascular death and worsening heart failure — though that broader endpoint did not reach statistical significance on its own.

Both figures deserve weight. A 25% reduction in hospitalisations is meaningful: admissions are distressing, expensive, and each one is associated with worse subsequent outcomes. The composite result points in the same direction without meeting the threshold, which is consistent with a real but modest effect in a trial not powered to detect it on that measure.

What the trial does not demonstrate is a mortality benefit, and nothing here changes digoxin’s position relative to drugs that have one.

Why a cheap drug result matters disproportionately

Modern heart-failure care increasingly relies on newer, expensive medicines. Several are transformative and cost enough that access is genuinely constrained in much of the world.

A positive result for a generic costing pennies a day is therefore worth more than the effect size alone suggests, particularly where cost is the binding constraint on treatment.

It is also the kind of trial that rarely gets run. No company has a commercial interest in demonstrating that an off-patent drug works, which is why questions about old cheap medicines remain open for decades while new expensive ones are studied intensively.

The practical caveat

Digoxin needs careful dosing and monitoring — too much can be toxic — and that requirement does not disappear with a low-dose strategy. It requires blood level checks, attention to kidney function and awareness of interactions, which is a real burden in health systems where monitoring is difficult.

What heart-failure treatment looks like now

Understanding why an old cheap drug adding benefit is notable requires knowing what it is adding to.

Contemporary treatment for heart failure with reduced ejection fraction rests on four drug classes used together, each with demonstrated mortality benefit in large trials. Building that regimen took three decades, and getting patients onto all four at target doses remains a persistent clinical challenge in itself.

That is a high bar for anything new. A drug must show benefit on top of four established therapies in patients already receiving them, which is why many candidates that would have succeeded twenty years ago now fail.

It also explains the endpoint. With mortality already substantially reduced by existing treatment, demonstrating a further survival benefit requires enormous trials. Hospitalisation is more frequent, so it can be measured in a study of a thousand patients — and it is an outcome patients and health systems care about independently, since admissions are both distressing and expensive.

A cheap drug needing laboratory supervision is not straightforwardly cheap. This describes clinical-trial findings and is not medical advice. Decisions about heart-failure medication should be made with a qualified clinician.