[Best result of digoxin dosing in the aged by taking into account that both the elimination as well as the volume of distribution of the drug decrease when the kidney function deteriorates]. / Mejor resultado del ajuste de la dosis de digoxina en ancianos si se tiene en cuenta que tanto la eliminación como el volumen de distribución del fármaco disminuyen cuando se reduce la función renal.

PURPOSE: To evaluate three methods for digoxin dose adjustment in aged patients. METHODS: We determined the plasma digoxin levels that would be attained in 87 old patients with doses adjusted to the kidney function by means of three separate procedures. RESULTS: Age: 79.0 "6.3 years of age; creatinin clearance (Clc): 0.70" 0.23 ml/Kg of lean body weight and minute. Only the methods that adjust both the digoxin clearance and the volume of distribution to the Clc achieve the independence between the digoxinemia and the kidney function. The best of them, by calculating the elimination constant (K) and the volume of distribution (V) as linear functions of the Clc, so that K ranges between 0.173 and 0.462 days-1 and V between 4 and 10 l/Kg of lean body weight when the Clc varies from 0 to 110 ml/minute, achieve digoxinemia figures between 0.8 y 2.0 ng/ml and above 2.0 ng/ml in the 81.6% and 0.0% of the patients (95% confidence intervals (95% CI): 72.2% to 88.4 and 0.0% to 4.6%), respectively; with a precision and a bias of 0.43 and -0.06 ng/ml (95% CI: 0.38 to 0.48 and -0.16 to 0.03 ng/ml), respectively. CONCLUSION: The described method would lead to good results if digoxin has not been prescribed in order to control the cardiac frequency in the setting of auricular fibrilation.

[Ambulatory therapeutic noncompliance of the aged treated with digoxin]. / Incumplimiento terapéutico ambulatorio en ancianos tratados con digoxina.

OBJECTIVE: To quantify the percentage of out-patient doses (OPD) of Digoxin taken by elderly people in treatment. DESIGN: An observational, longitudinal and retrospective study. SETTING: Out-patient clinics at a geriatric hospital. PATIENTS: 67 patients were treated orally with Digoxin: 39 women; age 79 +/- 6; ideal weight, 55.7 Kg +/- 7.1; plasma creatinine, 1.3 +/- 0.9 mg/dl; in-hospital dose 3247.6 +/- 1309.4 ng/Kg; out-patient dose, 3205.7 +/- 1359.9 ng/Kg. They had two consecutive Digoxinemias, one in and one out of hospital, with an interval of 1 to 18 months between them. MEASUREMENTS AND MAIN RESULTS: Therapeutic compliance was calculated by comparing the Digoxinemia/dose relationship per Kg of the ideal in-hospital weight against the non-hospital one. 37.3% of the patients ingested 80 to 110% of the OPD (95% CI, 26.7%-49.3%). The 36 patients on a constant dosage took 74.3% +/- 34.1% of the OPD, whereas the 31 not on a daily dose took 87.7% +/- 25.3% (P < 0.07). CONCLUSIONS: Non-compliance is common and hard to detect clinically. Therefore, it is dangerous to adjust the dose of non-compliant patients only on the basis of Digoxinemias or effects of the medicine, or on the doctor's view about compliance.