Digoxin toxicity

It gets excreted from the distal tubule by active secretion

So drugs which compete with this mechanism may lead to toxicity

• Quinine
• Verapamil
• Amiodarone
• Spironolactone

In severe renal failure tubular function is compromised, leading to accumulation of digoxin

Digoxin causes AV block and arrhythmias (so avoid in WPW where the accessory pathway may be triggered) ('reversed tick' ST and 1^st degree heart block are normal findings)

A herald of toxicity may present as pulsus bigeminus (normal QRS and ventricular ectopics)

The elderly are generally at risk. Particularly so if they also have:

• hypokalaemia
• hypoxia
• hypomagnesaemia
• hypothyroidism
• hypercalcaemia    ...........so.........hardly any of them then!

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