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DifFerences in serum digoxin concentrations between outpatients and inpatients: An effect of compliance?
Author(s) -
Sheiner Lewis B.,
Rosenberg Barr,
Marathe Vinay V.,
Peck Carl
Publication year - 1974
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1002/cpt1974153239
Subject(s) - digoxin , pharmacokinetics , medicine , confidence interval , serum concentration , compliance (psychology) , volunteer , drug , drug compliance , consistency (knowledge bases) , pharmacology , heart failure , psychology , biology , mathematics , social psychology , agronomy , geometry
Concentrations of digoxin in serum were assayed at serial weekly visits (2 to 8) of outpatients receiving the drug (163 assays in 43 patients). A data analysis technique that models individual pharmacokinetics using routine clinical, laboratory, and drug concentration data was used to estimate mean pharmacokinetic parameters, the between‐individual variation in these, and average within‐individual serum digoxin concentration variation. Outpatient serum digoxin concentrations averaged only 72% of the amount expected after size, renal function, and stated dose were taken into account in a manner determined by inpatient data previously obtained. The 95% confidence region for mean steady‐state serum digoxin concentrations in individualoutpatients ranges from 40% to 104% of the concentrations expected. These findings may be explained by variable outpatient compliance with prescribed doses. Although highly variable between individuals, it seems remarkably constant for each individual over a 2 to 8 week period. If additional studies confirm these results, outpatient compliance may be a graded and predictable phenomenon. Using the technique of data analysis suggested in this paper and periodic measurement of serum digoxin concentrations, individual compliance and its consistency over time can be assessed. Such information may assist in patient management.