2.1 Positive inotropic drugs

2.1.1 Cardiac glycosides

Tablets 62.5 micrograms, 125 micrograms, 250 micrograms (£2.10 = 125 micrograms daily)
Elixir 50 micrograms/ml (£5.35 = 60ml)
Injection 250 micrograms/ml
Injection 100microgram/ml (unlicensed special)

Indications

Dose

Notes

Avoid hypokalaemia as this increases digoxin toxicity. Suggested potassium levels are between 4 and 5mmol/L.
If a diuretic is also required, the co-prescription of a potassium sparing diuretic may be indicated.
Digoxin excretion is renal therefore review the dose as the patient ages or is on other drugs which may impair renal excretion, e.g. NSAIDs, ACE inhibitors/angiotensin-II receptor blockers (ARBs).
Digoxin is highly plasma protein bound and interacts with drugs which compete for binding sites (e.g. amiodarone); the dose may therefore need modifying.
If toxicity is suspected, digoxin levels may be measured. Take sample at least 6 hours after the last dose.
If converting from tablets/elixir to injection the dose should be reduced (125 microgram orally is approximately equivalent to 100 microgram by injection).
Infusion-related adverse events include dizziness, blurred or yellow vision, arrhythmias, nausea, vomiting. Rapid administration may cause hypertension and reduced coronary flow. Avoid bolus administration as more likely to cause adverse effects.
Digoxin is contraindicated in Wolff Parkinson White syndrome. It does not prevent paroxysmal atrial fibrillation or control the rate when it occurs.

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