Digoxin Compliance: A Pharmacokinetic Quantification

To quantify extent of compliance in patients receiving digoxin by implementing an applied pharmacokinetic approach and to determine the percentage of patients with levels within therapeutic range.
One hundred-nineteen patients, whom met the required criteria, were enrolled in this study. Based on their digoxin doses, they were divided into 4 groups. Group A took 1 tablet (0.25 mg) per day, group B received half a tablet (0.125 mg) each day, group C used 6 tablets per week, and group D took 5 tablets per week and two days were off the drug. A pharmacokinetic approach was used to predict the serum digoxin concentrations of patients and the expected levels were compared with the actual concentrations.
52.29% of patients were compliant. There was no significant difference between the compliant and non-compliant groups with regard to gender, age, and number of concurrent medications or duration of digoxin intake. However, with respect to their doses, a significant difference existed between 2 groups (p<0.01). Patients in group D were more compliant (80.56%). In addition, their serum digoxin concentrations were relatively more within the therapeutic range (89.66%). Therefore, patients with the lowest frequency of digoxin intake were more compliant.
The results of this study indicate that a considerable number of patients do not take digoxin as directed. Patients with the least frequency of digoxin intake were relatively more compliant.