Haemodynamic effects of the antiarrhythmic quaternary ammonium compound QX-572 in man

Lidocaine and the quarternary ammonium compound QX-572 in acute myocardial infarction. A comparative study

Patients with suspected or proven acute myocardial infarction complicated by ventricular arrhythmias not corrected by lidocaine therapy (bolus dose 100 mg followed by infusion 2 mg/min) were treated either with an increased dose of lidocaine (bolus dose 50 mg followed by infusion 3 mg/min) or with 600 mg N,N-bis dimethylammonium chloride (QX-572, Astra, Sweden) as an i.v. infusion during 30 min (3 patients) or 60 min (13 patients). In the lidocaine group the arrhythmias were controlled in 6 out of 15 patients, in the QZ-572 group in 12 out of 16, a difference that is not statistically significant. However, the frequency of side-effects was significantly higher (p less than 0.001) in the QX-572 group (15 out of 16 patients). They were also more severe, including pronounced tachycardia and hypertension. It is concluded that despite the high antiarrhythmic effect of QX-572, an increase of the lidocaine dose would be safer and preferable in the clinical situation studied.

Haemodynamic effects of the quaternary ammonium compound QX 572 in anaesthetized cats. I. Cardiac chronotropic effects

The haemodynamic effects of the antiarrhythmic compound, QX 572, have been studied in anaesthetized cats. It was found that QX 572 increased the heart rate and decreased the blood pressure of the cats during the infusion of the drug. A slight increase in blood pressure was seen after the infusion was terminated. The same results have been obtained in patients. Experiments on cats pretreated with propranolol or reserpine showed that infusions of QX 572 caused an increase in heart rate by increasing the sympathetic activity in the cats. It is also shown that changes in vagal tone may contribute to the effects of QX 572 on the heart rate.

Plasma concentrations and urinary excretion of the antiarrhythmic quaternary ammonium compound QX-572 in man

A quantitative thin layer chromatographic (TLC) method has been developed for determination of the antiarrhythmic quaternary ammonium compound N,N-bis (phenylcarbamoyl methyl) dimethylammonium chloride (QX-572) in biological materials. Prior to chromatography QX-572 was transferred into chloroform as perchlorate by ion pair extraction. Tritium-labelled QX-572 was used as the internal standard and a TLC scanning spectrophotometer equipped with a linear detector system afforded the required accuracy, specificity and simplicity. The method was used to determine QX-572 in plasma from 11 patients with various cardiac diseases who received QX-572 8 mg/kg body wt. as an intravenous infusion over 30 min. There was a rapid initial decay of the plasma levels from 11.0+/-1.1 mug/ml (mean+/-SE) at the end of infusion to 3.5+/-0.5 mug/ml after 30 min. 240 min after commencement of the infusion the plasma level was 0.7+/-0.1 mug/ml. In these patients 22+/-2% (mean+/-SE) of the total administered dose of QX-572 was excreted unchanged in urine during the 24 hours following infusion of the drug. A second group of 28 patients with acute myocardial infarction also received QX-572 8 mg/kg body wt. Their plasma levels did not differ significantly from those found in the first group of patients. There was a poor correlation between the amount of QX-572 administered and plasma level at the end of the infusion. The study has provided some preliminary data about the pharmacokinetics of QX-572, but before a detailed analysis can be done data from longer periods of observation is required. The present results suggest that in future QX-572 can be administered in a standardized dosage, what would be advantageous in practice.

Effects of the quaternary ammonium compound OX-572 on ventricular tachyarrhythmias complicating acute myocardial infarction

Patients with acute myocardial infarction who developed defined ventricular tachyarrhythmias were randomly allocated to two groups. The patients (n=34) in one of the groups received the quaternary ammonium compound N,N-bis (phenylcarbamoylmethyl) dimethylammoniumchloride (QX-572) intravenously as an infusion of 8 mg/kg body weight over 30 minutes. The patients in the other group (n=33) received saline and acted as controls. The analysis of arrhythmias was based on a continuous electrocardiogram recorded in parallel to routine monitoring during the 24 hours after the start of infusion. Only the detection of ventricular tachycardia or the development of ventricular fibrillation on routine monitoring could induce a change in antiarrhythmic treatment. The incidence of patients with ventricular tachycardia recorded was significantly lower in the QX-572 group (38%) than in the control group (73%). About half the number of patients with ventricular tachycardia recorded on the continuous electrocardiogram were also detected by means of routine monitoring. The number of patients with various types of ventricular premature contractions (1-5/min, greater than 5/min, paired, multifocal, R on T), ventricular tachycardia, and rapid idioventricular rhythm were compared within successive one-hour periods. For all types of ventricular tachyarrhythmias except rapid idioventricular rhythm there was a lower incidence of arrhythmias in the QX-572 group...