In vivo interaction of the enantiomers of disopyramide in human subjects.

Disopyramide, an antiarrhythmic agent, is marketed as a racemic mixture of two enantiomers. The racemic drug has unusual pharmacokinetic properties because of its concentration-dependent binding to plasma proteins in the therapeutic plasma concentration range. This study examined, in healthy subjects, the individual pharmacokinetic properties of both total and unbound d- and 1-disopyramide in plasma after intravenous administration of each enantiomer separately (1.

Amitriptyline disposition in young and elderly normal men.

The disposition of a single parenteral or single oral dose of amitriptyline was followed in seven young (mean age 22 yr, range 21 to 23) and five elderly (mean age 71 yr, range 62 to 81) healthy men. The mean systemic clearance did not change with age (10.8 +/- 2.

Effect of low doses of heparin on the plasma binding of phenytoin and prazosin in normal man.

The effect of low doses of heparin on the binding of phenytoin and prazosin to plasma proteins was evaluated in four normal subjects. Heparin activates the hydrolysis of triglycerides in plasma. The ensuing increase in non-esterified fatty acids (NEFA) was more marked in vitro than in vivo and increased the free fraction (FF) of phenytoin and prazosin in plasma.

The cardiac effects of d- and l-disopyramide in normal subjects: a noninvasive study.

Commercially available disopyramide is a racemic mixture of equal parts of dextrorotatory (d-) and levorotatory (l-) optical isomers. We studied the cardiac effects of i.v.

The effect of saturable binding to plasma proteins on the pharmacokinetic properties of disopyramide.

Disopyramide exhibits saturable binding to plasma proteins in the therapeutic plasma concentration range. Because of this property, controversy exists in the literature regarding the pharmacokinetic properties of the drug. The purposes of this study were to reassess the pharmacokinetic properties of disopyramide in humans, taking into consideration both total and unbound concentrations and to use disopyramide as a model compound to study the effect of drug binding on the renal clearance of both total and unbound drug.