Ajmaline is extracted from the roots of Rauwolfia serpentina, the Indian snake root. It is available by prescription and is used to treat cardiac arrhythmias. In Germany, it is available under the trade name Gilurytmal.
What is ajmaline?
Ajmaline is extracted from the roots of Rauwolfia serpentina, the Indian snake root. It is available by prescription and is used to treat cardiac arrhythmias. Ajmaline is an indole alkaloid. The active ingredient of Indian snake root is prescribed in the prescription drug Gilurytmal of class I antiarrhythmics for cardiac arrhythmias in the form of supraventricular tachycardia. These arrhythmias to be treated with ajmaline must be accompanied by accelerated pulse beats and originate in the atria. These arrhythmias include, for example, palpitations originating from the AV node, palpitations in WPW syndrome, or paroxysmal atrial fibrillation. Ajmaline is also used in emergency medicine for the acute treatment of symptomatic supraventricular tachycardia requiring treatment and for life-threatening ventricular tachycardia. The active ingredient ajmaline is available as 50 mg/10 ml solution for injection and is always injected intravenously. Later, 90% of the active ingredient is excreted by the liver and 10% by the kidneys.
Pharmacological action
Ajmaline functions as a sodium channel antagonist. It delays the influx of sodium ions into cardiac muscle cells. Muscle cells require sodium ions to contract. This reduces excitation propagation in the fast-conducting areas of the heart. This prolongs the action potential duration in the atria and ventricles. As a consequence, the functional refractory period is also prolonged, which in turn leads to an increased stimulus threshold. Overall, this results in a slower heartbeat and a reduction in the beating force of the heart. The effect on the general cardiovascular system is rather small. Nevertheless, careful attention should be paid to a possible negative inotropy as well as bradycardia tendency. The pharmacological effect lasts up to 2 minutes and lasts for about 20 minutes. Thus, it can be well controlled. It is recommended to inject ajmaline very slowly to avoid accidental overdose. 5 minutes is a good length of time for the injection. For an already pre-damaged heart, it should be a few minutes more.
Medical application and use
Ajmaline is used to treat cardiac arrhythmias that originate in the atria and are accompanied by an accelerated heart rate. Supraventricular tachyarrhythmias such as AV junctional tachycardia, supraventricular tachycardia in WPW syndrome, or paroxysmal atrial fibrillation, which are symptomatic and require therapy, are among the classic applications of ajmaline. Furthermore, life-threatening ventricular tachycardias are also included. Thus, Ajmaline is also excellently suited for use in emergency medicine. The effect sought with the administration of ajmaline can be captured in two points:
- Slowing of the heartbeat
- Attenuation of the conduction of excitation in the heart
Ajmaline as a drug of class I antiarrhythmics should not be combined with other antiarrhythmics of this class. Otherwise, there is a risk of serious side effects. Also, a combination with drugs such as beta-blockers or calcium channel blockers increases the effect on the AV conduction of the excitation conduction system of the heart and reduces its pumping capacity. Especially when ajmaline is administered by continuous drip infusion, it should be borne in mind that it increases the effect of drugs such as beta-blockers, antidepressants, and neuroleptics, since it interferes with their degradation in the organism. Therapy with ajmaline is excluded in:
- Ajmaline hypersensitivity
- AV block of the II. as well as III. degree
- Pre-existing excitation conduction disorders in the ventricles.
- Existing myocardial weakness, because ajmaline would aggravate it clear increase in excitation propagation within the ventricles or in the case of prolongation of the complete electrical ventricular function, because it could be additionally delayed
- Adam Stokes seizures
- Myasthenia gravis
- Intoxication with cardiac glycosides
- Bradycardia
- Pathological enlargement of the heart muscle
- Within the first 3 months after myocardial infarction
- Left ventricular failure with less than 35% of normal output
Risks and side effects
A feared side effect of ajmaline is paradoxical proarrhythmic reactions of the heart. They can occur especially in people with CHD. Rarely, seizures occur, and even more rarely, blood count changes. In addition to the exclusion criteria listed for medical use, Ajmaline is still not to be used in cases of marked hypotension and severe electrolyte disturbance. An exception may be made for SA block, higher degree AV block, sinus node syndrome, and severe bradycardia if the patient is wearing a pacemaker. Because ajmaline is excreted by the liver and kidneys, dosage should be adjusted if hepatic or renal function is impaired.
