Abstract
A patient, 43-year-old woman with arrhythmias, was receiving continuous ambulatory peritoneal dialysis (CAPD). Initially she was given 100mg disopyramide (DSP) as a single oral dose, but was admitted because of poor control. The dose of DSP was increased to 200mg in two divided doses, resulting in the appearance of visual disorders. The dose was therefore reduced to 100mg given as a single dose, but the visual abnormalities persisted. Since the patient developed nausea due to blurring of vision and became anorectic, the monitoring of serum DSP concentrations was started. Based on the pharmacokinetics, we speculated that the side effects were due to a high Cmax (2.87μg/ml) and that episodes of arrhythmias were due to a low Cmin (0.75μg/ml). The dosage regimen was therefore changed to 100mg, in two doses of 50mg, in an attempt to reduce fluctuation in the serum DSP concentration. Subsequently, Cmax and Cmin stabilized at 2.52 and 1.31μg/ml, respectively, achieving good control of arrhythmias without side effects.
