Digoxin + antibacterial drugs, the combination of drugs should be cautious

*For medical professionals only

Clinical decision-making can be simpler

Suggestions for combined use

Oral neomycin lowers digoxin levels, and intramuscular gentamicin raises digoxin levels.

Relevant clinical evidence

In one study, 12 patients with congestive heart failure took digoxin 250 μg daily, plus gentamicin 80 mg intramuscularly twice daily for 7 days, and serum digoxin levels were found to be elevated by 129%.

In another 12 patients with congestive heart failure and diabetes, the same dose of gentamicin increased digoxin levels more than twice to 2 ng/mL. However, no symptoms of digoxin toxicity were present in the above patients.

It should be noted that before receiving gentamicin, serum creatinine levels in both groups were also higher than in the healthy control group and further increased after gentamicin administration.

An earlier study also found that gentamicin prolonged the half-life of digoxin and increased serum levels by 47% (from 1.9 to 2.8 ng/ml).

Mechanism analysis

Gentamicin impairs renal function, thereby reducing digoxin clearance.

Digoxin and serum creatinine levels are higher in diabetic patients compared to non-diabetic patients, possibly because of differences in renal function between diabetics and non-diabetic patients, and the combination of gentamicin can further impair renal function, resulting in higher digoxin levels.

The reason for the absence of digoxin toxicity in the above patients has not been identified, which may involve changes in ion transport, and the inhibition of Na+/K+ATPase of digoxin-specific receptors by gentamicin is also a possible factor.

Neomycin can cause reversible malabsorption syndromes, which affect the absorption of several drugs. In some patients, this effect may be counteracted because neomycin also reduces the breakdown of digoxin by gut bacteria.

Important

Although information is limited, if patients are given gentamicin at the same time, patients should be monitored for increased levels of digoxin, particularly in patients with diabetes mellitus or any other patients with renal impairment.

If neomycin is given at the same time, patients should be monitored for decreased digoxin levels and appropriate dose adjustments should be made if necessary.

The administration of the two drugs separately does not prevent the interaction between the drug and digoxin. Other aminoglycosides that can be given orally, such as kanamycin and paromycin, may also interact similarly with neomycin, but further studies are needed to confirm it.

bibliography:

[1] Alkadi HO, Nooman MA, Raja’a YA. Effect of gentamicin on serum digoxin level in patients with congestive heart failure. Pharm World Sci (2004) 26, 107–9.

[2] Halawa B. Interactions of digoxin with cefradin (Sefril), tetracycline (Tetracyclinum), gentamicin (Gentamycin) and vancomycin (Vancocin). Pol Tyg Lek (1984) 39, 1717–20.

[3] Lindenbaum J, Maulitz RM, Butler VP. Inhibition of digoxin absorption by neomycin. Gastroenterology (1976) 71, 399–404.

[4] Lindenbaum J, Tse-Eng D, Butler VP, Rund DG. Urinary excretion of reduced metabolites of digoxin. Am J Med (1981) 71, 67–74.

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