Monitoring the dose of digoxin.

All patients being prescribed digoxin in a general practice were examined and the serum urea, creatinine, electrolytes, and digoxin concentrations were determined.Sixty-six patients were identified (0.73 per cent of the practice population). After excluding six, whose tablet-taking was unreliable, it was found that two patients had serum digoxin levels above the usually accepted upper limit and a total of 23 patients (38 per cent of the digoxin takers) had some alteration made to their dose, including eight whose digoxin was stopped. We believe that serum digoxin estimations are useful in determining the optimum dose of digoxin in general practice.