Rauwolfia Root
Traditional Uses
Hypertension and arrhythmia.
Mechanism of Action
Rauwolfia’s effects on the heart include decreasing myocardial excitability, inhibiting atrial-ventricular conduction, and extending the refractory period of the heart rhythm.1
Much of the medicinal effects of Rauwolfia serpentina and Rauwolfia vomitoria have been attributed
to the hypotensive indole alkaloid reserpine.2 Additional alkaloids found in Rauwolfia roots include the indoles ajmaline, ajmalicine, raubasine, imethylajmaline, methylisoajmaline, hydroxysarpagine, yohimbinic acid, and isorauhimbinic acid.3 The constituent ajmaline is thought to be antiarrhythmic.4
Before the advent of the current pharmaceutical options for hypertension (beta blockers, calcium channel blockers, and angiotensin-converting Inhibitors), reserpine was a mainstay in the management of hypertension. Reserpine acts via the CNS to reduce sympathetic tone, increase parasympathetic activity, and help normalize blood pressure, especially when because of stress and sympathetic nervous responses, as it may partially block adrenaline receptors.5 Reserpine’s ability to block adrenoreception on blood vessels can reduce stress-induced vasoconstriction contributing to hypertension or heart palpitations.
Research suggests that reserpine may deplete peripheral catecholamine stores, contributing to hypotensive effects.6,7 Reserpine also seems to bind to vesicular monoamine transporters (VMATs) with high affinity, blocking neurotransmitter uptake into the vesicle and ultimately depleting catecholamines from storage vesicles. The actions of reserpine on the VMAT result in an acute catecholamine release, followed by chronic inhibition of catecholamine secretion, as a result of diminished releasable stores of vesicular catecholamine.8
Mechanisms involving cellular calcium influx and transport are also involved with the initiation and development of hypertension as a result of constrictive effects on vascular smooth muscle; thus, Rauwolfia may elicit vascular relaxation, reducing peripheral resistance and improving blood pressure.9
Although Rauwolfia can help reduce blood pressure, its effects are more pronounced on the CNS than the peripheral nervous system, through activity at the diencephalon, as reserpine decreases the release and accumulation of noradrenaline.8 Rauwolfia has a mildly sedating effect, making this herb especially indicated for those with concomitant tension, overwork, or poor sleep.
Evidence-Based Research
A review of the few randomized and placebo controlled trials that have been conducted on reserpine in the treatment of hypertension reported that reserpine is an effective tool in managing hypertension but that additional and larger trials are needed.10 One study that examined 108 elderly patients with II stage hypertensive disease reported that reserpine decreased arterial pressure and peripheral vascular resistance while increasing oxygen saturation in the tissues.11
A Rauwolfia product called Serpina was given to more than 100 patients for periods of 1 month to
1 year. In the study, a daily dose of one to three Serpina tablets was well tolerated. The product caused sedation and usually improved sleep, and it promoted moderate hypotension, particularly in labile patients with hypertension and tachycardia. It also seemed to have a sympatholytic effect, but did not produce postural hypotension.12
A Cochrane meta-analysis of a Rauwolfia randomized controlled trial on human hypertension subjects assessed that Rauwolfia displayed similar efficacy to first-line antihypertensive drugs, without significant side effects.10 Much of the medicinal effects have been attributed to the alkaloids reserpine, ajmaline, and ajmalicine.13
Trouble sleeping (insomnia). Early evidence indicates that Indian snakeroot in a specific combination with two other herbs might help insomnia.
Nervousness.
Mental disorders such as schizophrenia.
Constipation.
Fever.
Liver problems.
Joint pain.
Spasms in the legs due to poor circulation.
Mild high blood pressure.
Other conditions.