Time-to-Onset Analysis of Drug-Induced Long QT Syndrome Based on a Spontaneous Reporting System for Adverse Drug Events

Long QT syndrome (LQTS) is a disorder of the heart’s electrical activity that infrequently causes severe ventricular arrhythmias such as a type of ventricular tachycardia called torsade de pointes (TdP) and ventricular fibrillation, which can be fatal. There have been no previous reports on the time-to-onset for LQTS based on data from spontaneous reporting systems. The aim of this study was to assess the time-to-onset of LQTS according to drug treatment. We analyzed the association between 113 drugs in 37 therapeutic categories and LQTS including TdP using data obtained from the Japanese Adverse Drug Event Report database. For signal detection, we used the reporting odds ratio (ROR). Furthermore, we analyzed the time-to-onset data and assessed the hazard type using the Weibull shape parameter. The RORs (95% confidence interval) for bepridil, amiodarone, pilsicainide, nilotinib, disopyramide, arsenic trioxide, clarithromycin, cibenzoline, donepezil, famotidine, sulpiride, and nifekalant were 174.4 (148.6–204.6), 17.3 (14.7–20.4), 52.0 (43.4–62.4), 13.9 (11.5–16.7), 69.3 (55.3–86.8), 54.2 (43.2–68.0), 4.7 (3.8–5.8), 19.9 (15.9–25.0), 8.1 (6.5–10.1), 3.2 (2.5–4.1), 7.1 (5.5–9.2), and 254.8 (168.5–385.4), respectively. The medians and quartiles of time-to-onset for aprindine (oral) and bepridil were 20.0 (11.0–35.8) and 18.0 (6.0–43.0) days, respectively. The lower 95% confidence interval of the shape parameter β of bepridil was over 1 and the hazard was considered to increase over time.Our study indicated that the pattern of LQTS onset might differ among drugs. Based on these results, careful long-term observation is recommended, especially for specific drugs such as bepridil and aprindine. This information may be useful for the prevention of sudden death following LQTS and for efficient therapeutic planning.

Pharmacological Cardioversion of Persistent Atrial Fibrillation With and Without a History of Drug-Resistant Paroxysmal Atrial Fibrillation

BACKGROUND

Suppression by antiarrhythmic drugs of the maintenance mechanisms could convert persistent atrial fibrillation (AF) to sinus rhythm (SR). Whether a history of drug-resistant paroxysmal AF (PAF) would affect the outcome of pharmacological conversion of persistent AF by bepridil or in combination with aprindine was evaluated in the present study.

METHODS AND RESULTS

The study group comprised 51 consecutive patients (24 men, 61+/-8 years) undergoing pharmacological conversion of persistent AF lasting >1 month. Drug-resistant PAF was defined as AF and at least 2 ineffective antiarrhythmic drugs for suppression of AF recurrence. Fast Fourier transform analysis of fibrillation waves was used to measure fibrillation cycle length (FCL) from the peak frequency. Fifteen patients had a history of drug-resistant PAF (Group I), and the remaining 36 did not (Group II) before diagnosis of persistent AF. Ten patients (67%) in Group I and 26 patients (72%) in Group II were restored to SR by bepridil alone or in combination with aprindine after 29+/-15 days of drug administration. Before conversion to SR, bepridil increased the FCL more in Group II than in Group I. During a 12-month follow-up period, 4 of 10 patients in Group I and 2 of 26 patients in Group II (p<0.01) had recurrence of persistent AF with bepridil alone or in combination with aprindine.

CONCLUSIONS

A history of drug-resistant PAF does not affect the efficacy of pharmacological conversion by bepridil or in combination with aprindine. However, recurrence of AF was significantly higher in patients with such a history.

Chronic administration of aprindine during maintenance hemodialysis

Aprindine was administered for 12 months to 8 hemodialysis patients suffering from arrhythmias. The serum aprindine concentration ranged from 0.3 to 0.6 microgram/ml, and did not increase with time during the 1-year treatment period. The PQ interval was temporarily prolonged in the first and second months, but the QRS and QT intervals were not changed by chronic aprindine treatment. The changes of the PQ interval in the second month of treatment were directly correlated with the serum aprindine concentration. No alterations of the ECG findings were observed when aprindine was discontinued. The cardiothoracic ratio (chest radiography) and laboratory findings were also not influenced by either aprindine treatment or its withdrawal. In conclusion, aprindine may be safely administered for at least 1 year to arrhythmia patients on maintenance hemodialysis.

Kinetics of frequency-dependent conduction delay by class I antiarrhythmic drugs in human atrium

We investigated use-dependent prolongation of interatrial conduction time (IACT) by class I antiarrhythmic drugs in 16 patients. Changes in IACT at the initiation of atrial pacing were used to evaluate the onset kinetics. We examined recovery kinetics by giving a single extra stimulus with a varying coupling interval after discontinuing train stimulation. Time constants of the onset kinetics were 1.52 +/- 0.15/n(fast) and 0.087 +/- 0.031/n(slow) for mexiletine, 0.075 +/- 0.015/n for aprindine, 0.078 +/- 0.019/n for disopyramide, and 0.050 +/- 0.006/n for pilsicainide. The recovery time constants were 203 +/- 66 ms for mexiletine, 1,021 +/- 162 ms for aprindine, 993 +/- 101 ms for disopyramide, and 2,930 +/- 569 ms for pilsicainide. Class I antiarrhythmic drugs produced use-dependent IACT prolongation in humans, with characteristic kinetics for each agent similar to that of depression of the maximum upstroke velocity of cardiac action potential (Vmax) reported in in vitro studies.

[A case of repetitive monomorphic ventricular tachycardia]

We present a case treated with aprindine and metoprolol combined with a DDD type pacemaker for repetitive monomorphic ventricular tachycardia. A 50-year-old man was admitted because of palpitation and near syncope attack. Electrocardiogram showed repetitive monomorphic ventricular tachycardias (RBBB LAD type) and R-R interval of about 440 msec and I degree A-V block in sinus rhythm. Electrophysiologic study disclosed that overdrive pacing in HRA suppressed ventricular tachycardias. Left ventriculography revealed a dilated left ventricular and decreased contractility. Antiarrhythmic agents such as quinidine sulfate, procainamide, disopyramide, mexiletine, lidocaine and propranolol were not effective. But, the combination of propranolol and aprindine decreased the rate of the ventricular tachycardia. With aprindine 60 mg/day and metoprolol 60 mg/day combined with the atrioventricular sequential pacing at 85/min, ventricular tachycardia completely disappeared.

Transport to intestinal lumen and peritoneal cavity of intravenously administered aprinidine in rats

Transfer of aprindine from the blood into the intestinal lumen or into the peritoneal cavity was examined after intravenous administration of the drug at a dose of 5 mg/kg in rats. The amount of the drug transferred from the blood into the intestinal lumen was much greater than into the peritoneal cavity. The average amounts of aprindine transported into the intestinal lumen and the peritoneal cavity were 0.12 and 0.03% of the dose (5 mg/kg) in 120 min, respectively. Thus, a notable difference in the clearance values of the drug was obtained between the intestinal lumen (14.8 ml/h) and the peritoneal cavity (4.94 ml/h). The net water flux showed that secretion predominated in the peritoneal transport while absorption overbalanced secretion in the intestinal transport. It seems likely that a solvent drag effect by water movement did not contribute much to the transport of aprindine from the blood to the intestinal lumen or the peritoneal cavity. The differences in transport across the two membranes could be due to differences in the surface area and other geometrical factors. Differences could also be due to a difference in the pharmacologic effects of the drug which causes a decrease in tissue splanchnic perfusion.

[Clinical effects and plasma concentration levels of aprindine hydrochloride in patients with tachyarrhythmias]

Aprindine hydrochloride (aprindine) was administered orally in 17 Japanese patients with supraventricular or ventricular tachyarrhythmias, and the clinical effects and plasma concentration levels were evaluated. The antiarrhythmic effects were defined using Holter ECG recordings. Aprindine was administered orally with a daily dose of 40 mg for 2 weeks in all cases, and aprindine, 60 mg daily, was administered for the next 2 weeks in patients who did not show sufficient antiarrhythmic effects with 40 mg of the drug. Aprindine was effective in 9 of 17 patients, and the mean plasma concentration level reached 0.6 micrograms/ml 2 weeks after the administration was started. Effective results were seen in 2 of the 4 patients receiving a daily dose of 60 mg, and the mean plasma concentration level reached 1.0 microgram/ml 2 weeks after the administration was started. Transient mild elevations of liver transaminases were observed in one patient and mild transient anemia was observed in another. These abnormal data disappeared although the drug administration was continued. In conclusion, the administration of a relatively small dose of aprindine and, consequently, low plasma concentration levels, are effective for cardiac tachyarrhythmias in Japanese patients.

Therapeutic effectiveness and plasma levels of single or combination use of class I antiarrhythmic agents for ventricular arrhythmias

The efficacy of disopyramide (DP), mexiletine (MX), aprindine (AP) and cibenzoline (CZ) on ventricular arrhythmias was compared (single drug therapy). In addition, the efficacy of the combination therapy of DP with MX was also studied (combination therapy). One hundred of the 106 patients completed the protocol of the single drug therapy. Fifty percent or more reduction in the frequency of ventricular premature contractions (VPCs) was obtained in 24 of 43 patients (56%) with DP, in 24 of 44 (55%) with MX, in 18 of 29 (62%) with AP and 10 of 18 (56%) with CZ. AP was comparatively more effective than the other drugs tested. DP was significantly effective on VPCs with organic heart disease as compared to idiopathic VPCs (p less than 0.05), while the other 3 drugs did not have such a tendency. With MX therapy, 10 of the 12 patients with fast VT rate (greater than or equal to 150 beats/min) showed a significant effect while only 4 of the 12 patients with non-fast VT rate (greater than or equal to 100 and 150 beats/min) had a significant one (p less than 0.05). On the other hand, DP, AP and CZ showed almost the same efficacy at any cycle length of VT. Six patients withdrew from the study, 4 because of digestive troubles with MX therapy, 1 because of micturition disturbances with DP and 1 because of skin rash with AP. The average therapeutic plasma levels of DP, MX, AP and CZ were 1.76 +/- 0.54 microgram/ml, 1.08 +/- 0.41 microgram/ml, 0.85 +/- 0.43 microgram/ml and 268.2 +/- 123.3 ng/ml, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Prophylactic antiarrhythmic therapy of high-risk survivors of myocardial infarction: lower mortality at 1 month but not at 1 year

To determine whether prophylactic antiarrhythmic therapy influences mortality in high-risk patients after acute myocardial infarction, 143 such patients were randomized in a double-blind individually dose-adjusted, placebo-controlled trial an average of 14 +/- 7 days after myocardial infarction and followed for 1 year. Patients were judged to be at high risk on the basis of (1) ejection fraction less than 40% (n = 60), (2) arrhythmias of Lown class 3 or higher (n = 26), or (3) both (n = 57). Aprindine was chosen because of its long half-life, few side effects, and antiarrhythmic efficacy. Baseline characteristics in the treatment arms did not differ. Holter-detected arrhythmias were reduced in aprindine-treated patients at 3 months (p less than .001) and at 1 year (p less than .001). One patient was lost to follow-up; in the remaining patients 1 year mortality was 20% (28/142; 12 aprindine and 16 placebo). There was no significant difference between the two study arms in overall mortality and sudden death. However, among those who died, median duration of survival was longer in aprindine-treated patients (86 vs 21.5 days) (p = .04). Although antiarrhythmic treatment with aprindine of high-risk patients after myocardial infarction does not affect 1 year survival, mortality appears to be delayed; thus there may be a role for short-term treatment before more definitive therapy such as surgery.

Effects of intravenous sotalol, aprindine and the combination of sotalol and aprindine on chronic high frequency ventricular arrhythmias in man

The comparative antiarrhythmic efficacy of three different intravenous drug regimens was evaluated in 12 symptomatic patients (mean age: 72 years) with chronic high frequency ventricular arrhythmias (mean: 834 PVCs h-1). In a cross-over study with latin square distribution the following drug regimens were administered intravenously to all patients aprindine 2 mg kg-1, sotalol 1.5 mg kg-1, aprindine 1 mg kg-1 & sotalol 0.75 mg kg-1. The mean percentage of PVC reduction was 41% (P less than 0.05) for aprindine 2 mg kg-1; 51% (P less than 0.05) for sotalol 1.5 mg kg-1 and 72% (P less than 0.01) for the combined drug therapy (aprindine 1 mg kg-1 and sotalol 0.75 mg kg-1). The mean plasma concentration was 1371 ng ml-1 after administration of aprindine 2 mg kg-1 and 1730 ng ml-1 after infusion of sotalol 1.5 mg kg-1. After combined drug therapy, mean plasma levels were 942 ng ml-1 for aprindine and 992 ng ml-1 for sotalol. The different drug regimens were well tolerated in all patients and no side-effects occurred. Combination therapy consisting of a drug that prolongs action potential duration with an antiarrhythmic agent that has a high affinity for the inactivated channels may thus achieve an antiarrhythmic efficacy comparable to single agent therapy, permitting the use of lower dosages.

Non-linear pharmacokinetics of aprindine hydrochloride in oral administration

The pharmacokinetics of oral aprindine hydrochloride (in the following briefly called aprindine; Aspenon) were studied in 38 patients with ventricular premature contractions following single or multiple administration. Oral administration of aprindine in a single dose of 100-150 mg resulted in a mean maximal plasma concentration of 0.77 microgram/ml and a mean elimination half-life of 26.5 h. With multiple oral administration in 10 mg and 20 mg doses at intervals of 8 h, plasma concentration reached a steady state in 1-2 weeks with either dosage rate. Stable plasma concentrations were maintained with little diurnal or day-to-day fluctuation. The mean steady-state minimal plasma concentration with a 10 mg dosage was 0.28 microgram/ml. With a 20 mg dosage, however, this was more than tripled to 0.89 microgram/ml. The elimination process after the final administration of the drug was slower than with single dosage, and deviated from the first-order kinetics to produce a convex curve on a semilogarithmic graph paper. From these results it was apparent that aprindine shows non-linear pharmacokinetic behavior within the therapeutic dosage range.

Dose-dependent pharmacokinetics of aprindine in healthy volunteers

The disposition of aprindine following a single oral dose can best be described by a two-compartment open model. The mean plasma half-life (t 1/2 beta) increased from 8.0 +/- 2.1 h (SD) after a 25 mg dose of 9.4 +/- 2.9 h after 50 mg and to 15.8 +/- 2.6 h after 100 mg, with a decrease in total plasma clearance (Cl/F) and volume of distribution at steady state (V dss/F) and during beta-phase (V d beta/F). The area under plasma concentration-time curve (AUC), maximum plasma concentration (C max) and the amount of unchanged aprindine excreted in the urine increased in a non-linear fashion with the increase in dose. The t 1/2 beta after multiple oral doses showed a 3-fold increase over the single dose value. These results indicate that aprindine shows dose-dependent non-linear kinetics.

Long-term follow-up of patients receiving aprindine. Safety and efficacy

Aprindine hydrochloride is an antiarrhythmic agent presently undergoing clinical trials in the United States. Because of the narrow therapeutic-toxic ratio observed for aprindine, the long-term follow-up of these patients is important in determining the potential clinical effectiveness of this drug. In this report we examine our experience with 30 patients with drug-resistant arrhythmias who were discharged receiving aprindine and who were followed up for a mean period of 25 months.

Aprindine therapy for refractory ventricular tachycardia

Aprindine hydrochloride has been extensively used in Europe for the management of ventricular and supraventricular arrhythmias. Success has been achieved even in those cases that have proven refractory to standard antiarrhythmic agents. In this report, we describe our experience with aprindine therapy in seven patients with ventricular tachycardia in whom standard antiarrhythmic agents had proven either ineffective or had caused intolerable side effects. Aprindine was effective in five cases, and it failed in two. Neurologic side effects, although common, were easily controlled with adjustment of the dose. Agranulocytosis, a rare but serious side effect, was encountered in one of our patients. Relevant literature on aprindine is reviewed.

Electrophysiologic drug testing in prophylaxis of sporadic paroxysmal atrial fibrillation: technique, application, and efficacy in severely symptomatic preexcitation patients

Electrophysiologic drug testing was performed in nine patients with severely symptomatic sporadic (2 to 13 [mean 4.2] attacks/24 months) paroxysmal atrial fibrillation (PAF). All patients had control inductions of sustained (greater than 30 seconds) AF by high right atrial stimulation, and attempted inductions following serial administration of drugs. Drugs tested were intravenous procainamide (1.0 to 1.5 gm) (five patients), intravenous propranolol (0.1 mg/kg) (three patients), oral quinidine (1.6 to 2.4 gm/day) six patients), oral disopyramide (1.2 to 1.6 gm/day) (four patients), and oral aprindine (100 to 250 mg/day) (four patients). In all patients, one or more drugs prevented induction of sustained AF: procainamide (one patient), quinidine (five patients), disopyramide (four patients), and aprindine (four patients). All patients were treated with drugs which prevented induction of sustained AF and followed for 8 to 40 (mean 24) months. Seven patients tolerated their drugs: six had no AF and one had several short nonsustained attacks. Two patients did not tolerate their drugs: one had paroxysmal palpitation (on decreased aprindine dosage), and one had AF (while off of aprindine). In conclusion, electrophysiologic drug testing is feasible in patients with sporadic PAF. Inability to induce sustained AF following drug administration suggests successful prophylaxis of spontaneous PAF with the same drug.

[Comparison of the efficacy of aprindine and quinidine in chronic ventricular rhythm disorders]

The object of this study was to compare the efficacity and the side effects of Aprindine and Quinidine in patients with stable ventricular arrhythmias. A series of 33 patients with chronic stable ventricular arrhythmias were given successively Aprindine and Quinidine on the principle of extrasystoles (VES) determined by computer analysis of Holter recordings. The VES were counted every hour and the statistical study used analysis of variance followed by linear contrast and also the sign test. The stability of the arrhythmia was verified by several control Holter recordings without therapy (average : 3,3 per patient). Low dose regimes were used in 17 patients (an average of 50 to 60mg/day Aprindine, and 481 mg Quinidine base), and Quinidine was shown to be the more active (p less than 0.05 to 0.003 according to the test used), reducing the number of VES by 39% compared to an average of 21% for Aprindine. In the other 16 patients with a higher dosage regime, 109 mg Aprindine and 707 mg Quinidine base, there was no significant difference between Quinidine and Aprindine (p less than 0.08 to 0.12), Quinidine reducing the number of VES by an average of 54%, and Aprindine by 36%. Quinidine caused diarrhoea in I patient on the low dose and 4 patients in the high dose regime. Aprindine caused neurological side effects in 2 patients on the low dose, and 7 patients on the high dose regime. Aprindine at 100 mg/day may therefore be used in the same manner as Quinidine at usual dosages as regards the incidence of side effects of the two drugs. However, the ratio of effective dose/toxic dose is lower with Aprindine than with Quinidine.

Pharmacokinetic study of aprindine and moxaprindine in dogs

Moxaprindine and aprindine were each administered to a group of six dogs at a single dose of 5.5 mg/kg by intravenous injection and at the same dose 14 days later by oral route. In each series the sequence of route of administration was randomized. In a second experiment, 8 to 12 weeks later, the dogs were treated for 5 successive days with the same drug at the dose of 5.5 mg/kg twice daily. Moxaprindine and aprindine are similar in several of their pharmacokinetic characteristics. Their plasma levels are suitably explained by a two-compartment open model. No significant differences are found between their respective terminal plasma half-lives nor their k12, k21 and kel values; on multiple dosing, the steady state is reached within 3 days with both drugs. However, the plasma levels of moxaprindine are twice as high as those of aprindine. Consequently the distribution volume of moxaprindine is half as small as that of aprindine. Moxaprindine is 95.3% protein bound at 1 microgram/ml and 93.6% at 2 microgram/ml; the corresponding values for aprindine are 98.3% and 98.1%. These differences may be of clinical significance as regards therapeutic effectiveness and safety of these two substances.

Ventricular tachycardia: prediction of response to oral aprindine with intravenous aprindine

Aprindine was administered both intravenously and orally to 25 patients with ventricular tachycardia refractory to conventional antiarrhythmic agents to test the hypothesis that the response to intravenous aprindine predicts the response to oral aprindine. Ten patients had incessant ventricular tachycardia and 15 had paroxysmal sustained inducible ventricular tachycardia. Eleven patients (43 percent) had conversion to sinus rhythm with intravenous aprindine (nine with incessant and two with paroxysmal sustained ventricular tachycardia). Thirteen patients (all with paroxysmal sustained ventricular tachycardia) manifested slowing of the tachycardia without conversion, whereas in one patient with incessant ventricular tachycardia, the tachycardia became less frequent and nonsustained after intravenous aprindine. All 11 patients who had conversion to sinus rhythm with intravenous aprindine remained free of ventricular tachycardia during oral treatment with aprindine (at 2 weeks) and for a follow-up period of 2 to 38 months (mean 16 +/- 13). Of the 14 patients who did not have conversion to sinus rhythm with intravenous aprindine, 12 had spontaneous or inducible ventricular tachycardia, or both, at evaluation 1 to 2 weeks after initiation of oral aprindine. In conclusion, administration of intravenous aprindine to patients with ventricular tachycardia is helpful in predicting the subsequent response to oral aprindine. In addition, the pattern of ventricular tachycardia predicted the response to aprindine; patients with incessant ventricular tachycardia tended to respond, and those with paroxysmal sustained ventricular tachycardia tended not to respond.

Aprindine

Aprindine is a long-acting antiarrhythmic agent, effective when administered orally or intravenously in the treatment of ventricular arrhythmias of varying etiologies. It may be especially useful in the treatment of the Wolff-Parkinson-White syndrome. To a lesser extent, it may be useful in the treatment of atrial arrhythmias. Side effects can be minimized by careful titration of the dose of aprindine. If the frequency of such serious side effects as cholestatic jaundice and agranulocytosis remains low enough, aprindine should prove to be a useful addition to currently available antiarrhythmic drugs.

Suppression of the repetitive ventricular response: an index of long-term antiarrhythmic effectiveness of aprindine for ventricular tachycardia in man

The repetitive ventricular response, defined as the production of two or more ventricular premature complexes in response to a single ventricular pacing stimulus, is common in patients with serious ventricular arrhythmias. Twenty-seven patients with refractory ventricular tachycardia were studied to determine whether acute suppression of the repetitive ventricular response by aprindine predicts long-term effectiveness of this agent. Twenty-three of the 27 patients had the repetitive ventricular response before intravenous administration of aprindine, whereas only 6 had the response after aprindine. All patients were maintained on a regimen of oral aprindine and evaluated repeatedly for a mean of 12 months. Twenty of the 21 patients who had no repetitive ventricular response after intravenous aprindine manifested clinical improvement compared with only 1 of the 6 in whom the repetitive response was present after aprindine (P less than 0.0005). Aprindine is a useful agent in refractory ventricular tachycardia, and the absence of the repetitive ventricular response after its intravenous administration predicts long-term clinical responsiveness to the oral form.

Prolongation of cardiac conduction times by intravenous aprindine in man

The acute electrophysiologic effects of intravenous aprindine were evaluated in 48 patients to assess the effect on conduction times and refractoriness in patients with severe cardiac disease and arrhythmias. The patients had not responded to conventional antiarrhythmic medications or had been unable to tolerate effective doses of conventional medications because of side effects. Eleven patients had an abnormal H-V interval, 9 had prolonged QRS duration and 22 had evidence of severe left ventricular dysfunction. Aprindine prolonged conduction transiently in the atria, the atrioventricular (A-V) node, the His-Purkinje system and the ventricles. The refractory times of the atria, the A-V node and the ventricles increased insignificantly, both functionally and statistically. Atrioventricular block did not develop in any patient, and side effects were minor. Thus, aprindine can be safely administered intravenously (10 to 15 mg/min) to severely ill patients with arrhythmias that are refractory to other medications even in the presence of underlying conduction system and myocardial disease.

Design of a study to evaluate drug therapy of serious ventricular rhythm disturbances after an acute myocardial infarction

A study was designed to investigate whether long-term use of aprindine can prevent sudden death from primary ventricular fibrillation. Patients with a proven recent myocardial infarction and malignant ventricular arrhythmias occurring late after the acute episode were asked to participate in a 1-yr, double-blind, randomized, placebo-controlled trial to suppress the rhythm disturbances observed on an ambulatory electrocardiogram. Particular care was taken to monitor drug adherence. Arrhythmia detection by ambulatory electrocardiography was used to assess drug efficacy; side-effects establish the maximum tollerated dose for each individual patient. Aprindine was therefore used under optimal circumstances. An interactive computer system served as a data base and provided the investigators and the monitoring committee with all the information required for a proper evaluation of the progress of the study.

Suppression of refractory arrhythmias by aprindine in patients with the Wolff-Parkinson-White syndrome

Four patients with supraventricular tachycardia associated with the Wolff-Parkinson-White syndrome were refractory to conventional pharmacological therapy and received aprindine hydrochloride intravenously and orally. Electrophysiological studies disclosed that intravenous aprindine caused increased refractoriness and slowed conduction in the atria, atrioventricular node, ventricles, and accessory pathway. The ability to induce supraventricular tachycardia with timed atrial and ventricular premature stimuli was totally abolished in all 4 patients after intravenous aprindine. Oral aprindine therapy, twice daily thereafter, provided symptomatic relief of the supraventricular tachycardia without significant side effects. Aprindine is useful in the management of supraventricular tachycardia associated with Wolff-Parkinson-White and may offer significant advantages over currently available therapy.

Cardiovascular and antiarrhythmic effects of aprindine (AC1802) during partial occlusion of a coronary artery in the pig

The effect of intravenously administered aprindine (AC1802) as a prophylactic agent against ventricular arrhythmias was studied in pigs. During the first 30 min of ischaemia 5 of the 22 untreated animals died because of ventricular fibrillation against 1 of the 23 animals pretreated with aprindine (P=0.09). Ventricular tachycardias were observed in 10 untreated animals and in none of the aprindine group (P=0.0002). The incidence of other arrhythmias was significantly less in the aprindine group compared with the untreated group (P less than 0.02).

Treatment of recurrent ventricular tachycardia and fibrillation with aprindine

Twenty-three patients with recurrent ventricular tachycardia or ventricular fibrillation, or both, were treated with aprindine, a new antiarrhythmic agent. It was found that: (1) no patient had a recurrence of ventricular fibrillation after aprindine therapy was begun, except as a terminal event subsequent to the development of acute myocardial infarction and cardiogenic shock or refractory congestive heart failure; (2) 6 patients experienced ventricular tachycardia after the loading dose, but with continued aprindine therapy the ventricular tachycardia was suppressed in 3 of these 6 patients, and a fourth patient was asymptomatic during brief paroxysms of ventricular tachycardia; (3) in 2 patients, aprindine was ineffective and was discontinued; (4) electrical cardioversion was not required in any patient receiving aprindine; (5) premature ventricular extrasystoles were decreased in 18 of the 23 patients treated with aprindine; (6) aprindine was discontinued in 1 patient because of intolerable side effects, although ventricular arrhythmias were suppressed in this patient; and (7) 5 patients died from acute myocardial infarction or severe heart failure while receiving aprindine.

Absorption, half-life, and toxicity of oral aprindine in patients with acute myocardial infarction

Plasma concentrations of aprindine were used to assess its absorption, toxicity and disappearance rate after oral administration to patients within 24 hours of admission to a coronary care unit. Despite high oral doses, absorption was so slow that in half the patients effective plasma levels (exceeding 0.70 mug/ml) were not found during the first 12 hours of treatment. Therefore the oral route should not be used to treat cases of acute myocardial infarction with severe ventricular dysrhythmias. Clinical tolerance was good; there was one episode of delirium tremens in a chronic alcoholic (aprindine plasma concentration: 3 mug/ml); no case of tremor or cerebellar syndrome was observed. Disappearance of aprindine from plasma was slow, by far exceeding the half-lives found in healthy volunteers, and ranging from 20 to over 100 h. The variability of biological half-life in individual patients makes plasma level determiniations necessary whenever aprindine is to be administered for a long period.