Why should cardiac glycosides be withheld prior to hemodialysis?

• A. They can accumulate to dangerous levels due to reduced clearance
• B. They are ineffective during dialysis
• C. They cause hyperkalemia during dialysis
• D. They increase urine production

Answer: (A)

Cardiac glycosides have a very narrow therapeutic range and are cleared mainly by the kidneys. In patients who will undergo hemodialysis, kidney function is effectively reduced, so the drug’s clearance is diminished. Digoxin, in particular, distributes widely in the body and is not significantly removed by dialysis, so levels can rise during renal impairment and around the dialysis session. Withholding the medication before dialysis helps prevent dangerous accumulation and toxicity from occurring as the body’s clearance is limited and dialysis won’t reliably “clear” the drug.

Avoid thinking of it as about the drug being “ineffective” during dialysis; the key issue is the risk of accumulation and toxicity due to reduced clearance and the poor removal of the drug by dialysis. Signs of digoxin toxicity—nausea, vomiting, bradycardia, arrhythmias—underscore why this precaution is important.