Background The lack of standardisation in digoxin impregnation prompted us to analyse plasma levels (Cp) of digoxin during the previous 5 months. There only were 16 patients monitored (56.2% men), aged 77.4±10.8 years, with a glomerular filtration rate (FG) of 47.2±23 mL/min. Of these, only 18.7% were performed after the first dose and only 12.5% took into account FG when dosing. The average Cp for digoxin was 1.43±1.0 ng/mL, with variability of 69.9%.

Purpose The development of a protocol of digoxin impregnation was proposed. A simple explanatory table was developed indicating the loading dose administered according to FG and recommended times for pharmacokinetic monitoring and the second dose.

Material and methods The protocol was agreed with some medical services (internal medicine, cardiology, emergencies, intensive care medicine and neurology) through clinical sessions given by the pharmacist. The pharmacists insisted on dose adjustment according to FG and monitoring plasma levels of digoxin after the first loading dose for a Bayesian estimation. The project started in November 2015 and pharmacokinetic monitoring carried out over 5 months was analysed prospectively. Data (age, sex, FG, service, Cp, protocol compliance and pharmacokinetic recommendations) were obtained from the unit of clinical pharmacokinetics through the computer application Gestlab.

Results A total of 32 patients (28.1% men), aged 81±7.6 years, with FG 56.3±22.9 mL/min were included in the analysis of protocol compliance. The distribution of requests for clinical service was: 37.5% internal medicine, 21.8% neurology, 21.8% cardiology and 6.2% emergencies. 84.4% of monitoring was performed after the first dose. In 62.5% of patients the dose was adjusted according to FG. The average level of digoxin Cp was 1.07±0.28 ng/mL.

Conclusion Favourable changes generated after application of the new protocol were better coordination among prescribers, an increase of 50% in the number of patients monitored, reducing the average Cp of digoxin in the first pharmacokinetic monitoring period, with less interindividual variability (26%).

No conflict of interest