The efficacy of Ajmaline in ventricular arrhythmias after failure of lidocaine therapy in the acute phase of myocardial infarction

Fatal poisoning with detajmium: identification of detajmium and its metabolites and artifacts by gas chromatography-mass spectrometry and quantification by high-performance liquid chromatography

After ingestion of an unknown dose of detajmium, a 14-year-old female collapsed with asystolia. Resuscitation efforts were not successful. A medicolegal autopsy was carried out, and blood, liver and gastric content were extracted and analyzed by gas chromatography-mass spectrometry (GC-MS). After derivatization with acetic anhydride, detajmium and twelve of its derivatives and metabolites were identified. The main metabolic pathways include hydroxylation and subsequent O-methylation of the indol ring, and oxidation as well as reduction of the C-21 hydroxyl function. Cleavage of the N-alkyl side-chain is a further, possibly non-enzymatic degradation pathway. Artifact formation induced by acetylation included dehydratation of the hydroxyl function of C-21 and the N-alkyl side-chain. The detajmium concentration in blood of the decreased was determined by high-performance liquid chromatography with fluorimetric detection (12 micrograms/ml).

Effect of ajmaline on sustained ventricular tachycardia induced by programmed electrical stimulation in conscious dogs after myocardial infarction

As yet the antiarrhythmic efficacy of ajmaline with regard to suppressing the induction of sustained ventricular tachycardia after myocardial infarction has not been determined. Therefore, programmed electrical stimulation was performed in 8 conscious, chronically instrumented mongrel dogs 8-20 days after a 4-hour occlusion of the left anterior descending coronary artery. At baseline all animals responded with sustained ventricular tachycardia. Thereafter, ajmaline was administered at two consecutive i.v. doses: a bolus of 0.7 mg kg-1 followed by infusion of 2 mg kg-1 h-1 and infusion of 4 mg kg-1 h-1. The induction of sustained ventricular tachycardia was prevented in 2/8 animals by 2 mg kg-1 h-1 ajmaline and in 1/8 animals by 4 mg kg-1 h-1 ajmaline. During sinus rhythm only 4 mg kg-1 h-1 ajmaline significantly increased QRS-duration and intraventricular activation times, but during rapid right ventricular pacing (cycle length = 330 ms) both doses of ajmaline increased QRS duration and intraventricular conduction times. 4 mg kg-1 h-1 ajmaline also increased the cycle length of induced sustained ventricular tachycardia. In 3 animals induction of sustained ventricular tachycardia during infusion of 4 mg kg-1 h-1 ajmaline was achieved by introduction of less extrastimuli than at baseline. Furthermore the coupling intervals of extrastimuli that induced sustained ventricular tachycardia were substantially prolonged by this dose. Inhomogeneity of conduction between left ventricular normal zone and left ventricular infarct zone was significantly increased by 4 mg kg-1 h-1 ajmaline during rapid right ventricular pacing, but not during sinus rhythm.(ABSTRACT TRUNCATED AT 250 WORDS)

Dual inhibition of platelet-activating factor and arachidonic acid metabolism by ajmaline and effect on carrageenan-induced rat paw oedema

The effects of ajmaline on human platelet aggregation, arachidonate metabolism and platelet activating factor (PAF)-induced lethality in rabbits were examined. Platelet aggregation induced by several stimuli (ADP, collagen, and PAF) was inhibited by increasing concentrations of ajmaline. The potency of ajmaline was higher when PAF was employed as stimulating agent in comparison with other agonists (IC50 70, 270 and 380 microM for PAF, ADP and collagen, respectively) whereas ajmaline had no effect against arachidonic acid-induced aggregation. In contrast however, ajmaline inhibited arachidonate metabolism by platelet homogenates. The formation of both thromboxane A2 and 12-hydroxy-eicosatetraenoic acid was inhibited by ajmaline with comparable potencies. Pretreatment of rabbits with ajmaline (50 mg kg-1) completely abolished the lethal effects of PAF (11 micrograms kg-1) given intravenously (P < 0.001). In addition, ajmaline at doses ranging from 50 to 100 mg kg-1 inhibited carrageenan-induced rat paw oedema (P < 0.001). In this test ajmaline was three times more potent than aspirin. In the light of these results we conclude that ajmaline, a known anti-arrhythmic agent is a PAF antagonist and a dual inhibitor of platelet cyclo-oxygenase and lipoxygenase enzymes with anti-inflammatory properties.

Pharmacologic treatment of supraventricular tachycardia: the German experience

Tachyarrhythmias that originate above the bifurcation of the bundle of His or in tissue proximal to it are classified as supraventricular tachyarrhythmias (SVTs). Primary treatment of SVT tries to influence the underlying disease. Symptomatic therapy is subdivided into drug therapy, electrotherapeutic tools (e.g., antitachycardia pacemakers, catheter ablation), and antiarrhythmic surgery. Antiarrhythmic agents that slow conduction and suppress premature beats are efficient for emergency and long-term treatment of SVTs. We evaluated some of the most relevant antiarrhythmic drugs in SVT, including propafenone, diprafenone, cibenzoline, sotalol, and diltiazem; in addition, usage and efficacy of quinidine/verapamil, disopyramide, amiodarone, ajmaline, adenosine, and flecainide are summarized. In 1990, the case load of supraventricular arrhythmias per physician in Germany was more than 30 patients seen per month. About 50% of them were treated with drug therapy; i.e., approximately 17 patients were treated with antiarrhythmic drugs per month per physician for supraventricular arrhythmias. The most important antiarrhythmic agents used in Germany are propafenone (40%), combination of quinidine and verapamil (23%), sotalol (12%), disopyramide (6%), flecainide (6%), and other (13%).

Monitoring of ajmaline in plasma with high-performance liquid chromatography

A rapid, reliable and sensitive assay for routine determination of ajmaline in plasma by high-performance liquid chromatography with fluorimetric detection is presented. A low limit of detection in plasma (less than 1 ng/ml ajmaline) could be achieved by the extraction of plasma samples and the use of fluorimetric detection. Deproteinization of the plasma sample instead of extraction, or the use of an ultraviolet detector, yielded a higher limit of detection (less than 50 ng/ml). Two different eluents were studied. Eluent 1 allowed clear separation of ajmaline from isoajmaline and sandwicine, but did not separate isoajamaline from sandwicine. With eluent 2, separation of isoajmaline and sandwicine was achieved, but separation of ajmaline from sandwicine was less optimal than with eluent 1. Therefore, eluent 1 was used for further clinical studies. No interference was observed from therapeutic doses of other commonly co-administered drugs, such as acetylsalicylic acid, digoxin, digitoxin, ranitidine, dopamine, dobutamine, furosemide, captopril or glycerol trinitrate. In addition, the chemical stability of ajmaline and a possible rearrangement of ajmaline to its stereoisomers isoajmaline and sandwicine was studied in vivo and in vitro. Ajmaline proved to be unusually stable under both in vivo and in vitro conditions.

Metabolic disposition of ajmaline

Urine was collected from six patients receiving a continuous infusion of 20 mg/h ajmaline. Pooled urine was extracted with and without enzymatic conjugate cleavage or hydrolysis with concentrated hydrochloric acid. The extracts were analyzed by gas chromatography/mass spectrometry. Ajmaline and its metabolites in urine were identified in the form of their acetylated derivatives. Twenty two different acetylated derivatives of ajmaline and its metabolites could be detected. Three of these derivatives were artifacts generated by acetylation and/or thermal decomposition. The major metabolic pathways were mono- and di-hydroxylation of the benzene ring with subsequent O-methylation, reduction of the C-21, oxidation of the C-17 and C-21-hydroxyl function, N-oxidation, and a combination of these metabolic steps. Ajmaline and its metabolites were mainly excreted in the form of their conjugates. Furthermore, the interference of sparteine, debrisoquine, quinidine, and nifedipine with ajmaline metabolism was studied with semiquantitative thin-layer chromatography. Ajmaline metabolism was inhibited by co-administration of sparteine or quinidine, but not by debrisoquine or nifedipine. Sparteine most likely competed with ajmaline metabolism. Quinidine probably bound competitively to ajmaline-metabolizing enzymes without being metabolized itself. Additionally, the metabolic ratio of hydroxyajmaline/ajmaline in urine was determined in 9 extensive metabolizers and one poor metabolizer of dextromethorphan. The poor metabolizer had a significantly reduced metabolic ratio of hydroxyajmaline/ajmaline, which indicates that ajmaline metabolism probably co-segregates with polymorphic sparteine/debrisoquine/dextromethorphan metabolism.

Unmasking of sinus node dysfunction by ajmaline

A 75-year-old male with bifascicular block presented with recurrent giddiness and presyncope. Prolonged monitoring of the cardiac rhythm did not reveal any arrhythmia. Electrophysiological evaluation, including an ajmaline stress test, was performed. Ajmaline had an unusual effect. It reproducibly induced sinus arrest and thus unmasked a latent sick sinus syndrome.

Pharmacokinetics and antiarrhythmic efficacy of intravenous ajmaline in ventricular arrhythmia of acute onset

21 patients with acute myocardial infarction and ventricular arrhythmia of Lown class II-IIIB of acute onset received a short infusion of (50 mg/5 min) ajmaline (Gilurytmal). 6 of the patients had normal kidney and liver function (Group 1), 4 patients had acute renal failure and hemodialysis treatment (Group 2), 4 patients had impaired hepatic function (Group 3), 3 patients had cardiogenic shock (Group 4), and 4 patients had been pretreated with phenobarbital for seizures for at least 5 days (Group 5). A distribution half-life of 6 +/- 1 min and an elimination half-life of 95 +/- 6 min was determined in Group 1. The total plasma clearance was significantly lower in patients with impaired liver or cardiac function and significantly higher in Group 5, whereas impaired renal function did not affect total plasma clearance. After short infusion, ventricular arrhythmia of Lown II-IIIB completely disappeared for at least 16 to 36 min (mean: 19 min), which was associated with an ajmaline plasma level of 0.1-0.45 micrograms/ml. Additionally, steady-state plasma levels of ajmaline were determined after continuous infusion of 10-50 mg/h to 16 patients (Group 6) with ventricular arrhythmia of acute onset (Lown class IVA-V). Ventricular arrhythmia completely disappeared or at least changed to lower Lown classes at ajmaline plasma levels of 0.4-2.0 micrograms/ml. The ajmaline plasma protein binding was 76 +/- 9%. Ajmaline had a special affinity to alpha 1-acid glycoprotein.