A score for prescribing digoxin.

A simple method of selecting a maintenance dose of digoxin, suitable for an adult patient, was derived from data on 129 patients taking digoxin. Eight items of readily available information are required for entry into the prescribing aid: out/inpatient status, sex, age (less/not less than 70 years), weight (allocated to one of four ranges), whether or not chronically house/chair bound, cardiac rhythm (sinus/other), serum creatinine concentration (allocated to one of four ranges), and diuretic therapy (prescribed/not prescribed). The recommended dose is given in terms of size and number of tablets to be prescribed. Using this method 72.3 per cent of patients are expected to achieve mean steady state serum digoxin concentrations within the therapeutic range, 6.5 per cent above and 21.2 per cent below. This performance would be considerably better than that expected from the use of other prescribing aids. If available, routine measurement of the serum digoxin concentration during follow-up is recommended to detect those who might benefit from a change, usually an increase, in dose.