AJMALINE

Description

Rauwolfia (Luo Fu Mu) is derived from the plants Rauvolfia verticillata (Lour.) Baill. and R. yunnanensis Tsiang, and the root is usually used as its medicinal part. R. verticillata (Lour.) Baill. var. hainanensis Tsiang and R. vomitoria Afzel. ex Spreng have been also used as traditional Chinese herb.
Rauwolfia is one of the important traditional herbs in southern China. Its scope of treatment includes cold, fever, sore throat, headache, and dizziness caused by hypertension, abdominal pain and diarrhea, scabies, and so on. Rauwolfia is also used to treat insomniac dizziness, bruises, sprains, and venomous snake bites in folk.
In the “Flora of China,” 135 species of Rauwolfia were recorded, mostly distributed in the tropics and subtropics, a few in the temperate regions. There are nine species, four varieties, and three cultivated species in China.

Chemical properties

White Solid

Physical properties

Appearance: white or yellowish crystal powder. Melting point: its anhydride is 205– 207?°C. Optical rotation: +144° (chloroform). Solubility: well soluble in organic solvents, such as methanol, ethanol, etc., and slightly soluble in water. Storage temperature: 2–8?°C.

Originator

Ajmaline ,Solvay Pharma

History

Since 1930s, abundant studies have been focused on the Rauwolfia plants. So far, a total of 91 alkaloids were separated from Rauwolfia, and the identification of the chemical structures was obtained, including 2 non-indole alkaloids (thebaine and papaverine) and 89 indole alkaloids . In accordance with the basic framework, indole alkaloids can be divided into seven classes, such as the ajmaline class, the

The Uses of AJMALINE

An antiarrhythmic agent isolated from Rauwolfia serpentina.

The Uses of AJMALINE

For use as an antiarrhythmic agent.

Indications

For use as an antiarrhythmic agent.

Background

An alkaloid found in the root of Rauwolfia serpentina, among other plant sources. It is a class Ia antiarrhythmic agent that apparently acts by changing the shape and threshold of cardiac action potentials. Ajmaline produces potent sodium channel blocking effects and a very short half-life which makes it a very useful drug for acute intravenous treatments. The drug has been very popular in some countries for the treatment of atrial fibrillation in patients with the Wolff–Parkinson–White syndrome and in well tolerated monomorphic ventricular tachycardias. It has also been used for many years as a drug to challenge the conduction system of the heart in cases of bundle branch block and syncope. In these cases, abnormal prolongation of the HV interval has been taken as a proof for infrahisian conduction defects tributary for permanent pacemaker implantation.

Definition

ChEBI: A monoterpenoid indole alkaloid that consists of ajmalan substituted at positions 17 and 21 by hydroxy groups.

Manufacturing Process

Ajmaline isolated from Rauwolfia sp. roots: Rauwolfia serpentine Benth., Rauwolfia vomitoria Afr., Rauwolfia canescens L.
Threshed roots of Rauwolfia canescens L. extracted with 5% solution of acetic acid at room temperature for 24 h. Then extract was decanted to flask. This extract was alkalified with ammonia (alkaloid salts were converted to alkaloid bases). The obtained thus method solution was extracted with chloroform 3 or more times. Then chloroform extract was chromatographed on column through Al2O3 sorbent. After chromatography ajmalin was obtained, which had melting point at 205°C (recyrstallization from methanol).

Therapeutic Function

Antiarrhythmic

Pharmacokinetics

Ajmaline is a class 1A antiarrhythmic agent. By interfering with the sodium channels, this drug allows for improvement in abnormal rhythms of the heart

Pharmacology

Anti-arrhythmic R. serpentina (She Geng Mu) is the first anti-arrhythmic herbal medicine in the psychiatry history. Ajmaline has a potent anti-arrhythmic effect for treating atrial and ventricular arrhythmias and also has a good effect on the treatment of Wolff-Parkinson-White syndrome. Ajmaline plays a main role in decreasing the permeability of sodium ion on the myocardial cell membrane by moderately inhibiting the sodium channel. The electrophysiological effect of ajmaline is similar to that of quinidine, but it is stronger than quinidine.
In addition, ajmaline has a mild anti-sympathetic effect. It affects sympathetic nerve endings to release more sodium, dilate the coronary artery, relax vascular smooth muscle, and then decrease blood pressure. Therefore, it is suitable for clinical treatment of atrial and ventricular premature beats, pre-excitation syndrome with supraventricular tachycardia, but not suitable for the treatment of paroxysmal
atrial fibrillation and sinus tachycardia.

Clinical Use

Ajmaline has the anti-arrhythmic effects for the treatment of atrial or ventricular extrasystoles, paroxysmal supraventricular or ventricular tachycardia, and paroxysmal atrial fibrillation. The lethal dose for human ranged from 100 to 500?mg/kg.

Side Effects

Side effects include disturbances of the central nervous system and intrahepatic cholestasis.

Metabolism

Not Available

Purification Methods

Ajmaline crystallises from MeOH or EtOAc containing a little H2O to give the trihydrate m 158-160o. This loses 1H2O at 110o and all H2O at 150o. [Beilstein 23 III/IV 3212.]

References

Le Gall., Ann. ph arm. franc., 18,817 (1960)