Prescribing digoxin in geriatric units: The unexplained variability in dosage requirements

Abstract

Some physicians regard patients of Geriatric Units as a homogeneous population with respect to digoxin dosage requirements. Others advocate the use of pharmacokinetic models in prescribing digoxin for the elderly. Sixty in-patients of Geriatric Units were studied and the results compared with those previously obtained from 129 patients of other adult Units; all were receiving maintenance digoxin. For each patient the dose required to achieve a mean steady-state serum digoxin concentration of 1.6 nmol X l-1, the standardized dose, was calculated, assuming proportionality between the dose given and the concentration achieved. A mean of four estimates of standardized dose for each individual was used in the analysis. Threefold ranges of standardized dose covered the requirements of approximately 85% of patients both of Geriatric Units (62.5 to 187.5 micrograms per day) and of other adult Units (125 to 375 micrograms per day). The variables, serum creatinine concentration, sex, age, and body weight were of relatively little value in predicting the standardized dose for the patients in Geriatric Units. There was a sub-group of these in-patients for whom the standardized dose was extremely large.

Expression and Localization of P-glycoprotein in Human Heart

“…The cardiac glycoside digoxin has been unequivocally identified as a substrate for P-gp. The positive inotropic effects of digoxin exhibit a substantial inter-individual variability (Dobbs et al 1987), and cardiac P-gp may be one factor contributing to this effect. Moreover, several ␤ -blocking drugs have been described as P-gp substrates (e.g., talinolol, celiprolol; Karlsson et al 1993;Westphal et al 2000).…”

Effect of captopril on functional, physiological and biochemical outcome criteria in aged heart failure patients.

“…Appropriate digoxin maintenance (and where needed, loading) doses were selected (Dobbs et al, 1987). The daily dose of digoxin was then titrated to give a pre-dose serum digoxin concentration of 1.0 ug 1-1.…”

Digoxin: use pattern in Estonia and bioavailability of the local market leader

“…The bioavailability of digoxin can be variable. Several studies have shown considerable inter‐individual differences in bioavailability (7–9). Also, significant inter‐brand differences in digoxin bioavailability have been demonstrated in a number of studies (9–12).…”