Cardiac arrhythmias, electrolytes, and digoxin concentration in plasma and urine in patients treated with digoxin

A standard approach to compiling clinical pharmacokinetic data

A standard format for a Clinical Pharmacokinetic Summary is proposed. It consists of a heading, tables, notes, and references for each drug reviewed. The table presents a unified and logical set of clinically useful population pharmacokinetic parameters. They concern four major areas: absorption, distribution, elimination, and the relationship of concentration to effect. Within each major group, parameters dealing with extents and rates of processes are given. Each such parameter is really two: a population mea value (for example, average volume of distribution) and the standard deviation of individual values about this mean. The first value allows individual predictions of dosage or drug level to be made; the second allows computation of the likely proximity of subsequently observed quantities to those predictions. The table presents single consensus values for each population parameter, rather than a list of values. A procedure for computing these consensus values, and for revising them in the light of new data, or reinterpreted old data, is given. Examples of Summaries are given. The method appears applicable to a variety of drugs. We suggest our approach as a standard one for preparing Clinical Pharmacokinetic Summaries, and urge our colleagues to consider it for that purpose.

[Radioimmunological estimation of digoxin in urine (author's transl)]

When separating free and antibody bound digoxin, dextrancoated charcoal suspensions in protein-free urine dilutions develop an improve sieve effect which improves with aging of the suspensions. On addition of albumin to the dilution medium (buffer), the adsorptive capacities become stabilized. In urine dilutions less than of 1:50, false positive digoxin concentrations were measured. Determinations of 0-5 ng digoxin/ml in the diluted urine (1:100) and in the buffer solution show identical results. The recovery of added digoxin (1 ng and 2 ng/ml) is 100%; the lower detection limit is 3.6 mug/l urine. Between-assay variation for means of duplicates shows in the main measuring range (1.5-2.8 ng digoxin/ml) a variation coefficient less than of 4.5%; for a commercial test this value is distinctly higher. Dihydrodigoxin is measured at 3% only. Application of this method for measuring cumulative glycoside elimination of 5 healthy persons (0.5 mg digoxin daily intravenously during 2 weeks) results in a minimal interindividual variation of 5.1%. In a test preparation with a bioavailability of 94.6% the variation is 5.2%.