1 The plasma levels of disopyramide and mono-N-dealkyldisopyramide were measured from 118 patients, and the protein binding of both drugs from 50 patients during chronic oral disopyramide therapy. 2 No significant correlation was seen between the daily dose of disopyramide and the achieved plasma drug concentration. 3 The concentration of mono-N-dealkyldisopyramide in the plasma was about one third of that of disopyramide in patients with normal renal function. 4 The mean plasma levels of disopyramide and mono-N-dealkyldisopyramide were high in patients with renal impairment. In patients with simultaneous therapy with enzyme inducing drugs the mean levels of disopyramide were low and those of mono-N-dealkyldisopyramide high. 5 In patients with effective treatment of ventricular arrhythmias the levels of disopyramide were significantly higher than in those with ineffective treatment; the difference was not significant in supraventricular arrhythmias. Patients with side-effects had slightly though not significantly higher disopyramide levels than patients without side-effects; mono-N-dealkyldisopyramide concentrations were identical. 6 The average protein binding of disopyramide was 82%, and that of mono-N-dealkyldisopyramide 22-35%. Although a concentration dependent binding of disopyramide was seen within an individual, the average protein binding did not vary significantly at different concentrations of all samples analyzed. The protein binding was not altered in renal insufficiency, but was slightly decreased by high concentrations of mono-N-dealkyldisopyramide.
1 Monitoring plasma levels of mono‐N‐dealkyldisopyramide (MND), the most important metabolite of disopyramide, has been considered unnecessary. 2 We measured plasma levels of both disopyramide and MND in 64 consecutive patients receiving long term oral therapy with disopyramide. 3 Six patients were found with high plasma levels of MND, and simultaneously low levels of disopyramide. 4 Three of these patients were taking simultaneously phenytoin. The other three had a relatively high dose of disopyramide with regard to their renal function. One patient had terminal uremia, three had less severe renal dysfunction. 5 The underlying mechanism and clinical significance of the findings are discussed.
1 The effects of rifampicin, phenytoin, and disopyramide treatments on the metabolism of disopyramide were studied in patients and volunteers. 2 Rifampicin treatment markedly increased the metabolism of disopyramide. 3 Phenytoin had effects similar to those of rifampicin. The effect subsided in 2 weeks after stopping the treatment. 4 The metabolism of disopyramide seemed fastest in the patient group with the highest dose of disopyramide. Both in patients and volunteers a significant increase occurred in the urinary mono-Ndealkyldisopyramide/disopyramide ratio during the first week of disopyramide therapy. This change can partly be due to pharmacokinetic differences between disopyramide and its metabolite. The inducing effect of disopyramide remained uncertain.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.