Rauwolfia, Viscum, and Psicidia are well known herbs used in the treatment of hypertension. These herbs contain several different bioactive constituents including alkaloids, lectins, rotenones, flavonoids and isoflavones, among others, which research indicates as being cardioprotective, promote vascular health and reduce blood pressure. As the mechanisms of action are different for each herb, due to the varying bioactive compounds present, they can be used alone or in combination for these indications.
Patients being treated with the above-described herbs need to be carefully monitored, particularly for interactions with any concomitant antihypertensive medication—and herbal doses individually tailored.
AARM REFERENCE REVIEWS:
These are AARM reference reviews in which clinicians can obtain a quick overview of understanding with respect to how herbs, nutrients, and hormones can be used effectively in clinical practice. The dosages recommended are based on therapeutic results. Side effects that have not been seen in clinical experience or found in clinical studies but only been theorized have been identified and depicted as Unsubstantiated Theoretical Concerns.
Since many nutrients and herbs on the market have not gone through double-blind studies but have been used extensively in clinical settings for hundreds, and for some thousands of years, these reference reviews have attempted to give a unified opinion on how to use these herbs effectively. The opinions expressed are from different professors and experts in the field of nutritional and botanical medicine. Some information is based on personal opinions and can not be quantified as fact. However, if clinicians only restricted themselves to what is fully proven by double-blind studies, the art of healing and restoring health with nutrients and herbs would be lost.
The use of herbal medicines can be effective in the treatment of hypertension African snake root (Rauwolfia vomitoria), European Mistletoe (Viscum album) and Jamaican Dogwood (Piscidia erythrina) can normalize blood pressure via different mechanisms, and can synergistically support and tone the cardiovascular system. Rauwolfia, Viscum and Piscidia (alone or in combination with other herbs) support vascular tone, blood flow and viscosity, stress response, adrenaline and sympathetic nervous tone, and other mechanisms that enhance overall circulatory health and control blood pressure. In some subset of hypertensive patients, herbal medicines can be weaned off totally while patients remain normotensive.
KEY HERBS DISCUSSED:
African Snake Root (Rauwolfia vomitoria), European Mistletoe (Viscum album) and Jamaican Dogwood (Piscidia erythrina)
ADJUNCTIVE OR STAND-ALONE TREATMENT:
Adjunctive or Stand-Alone
Rauwolfia: Diverse alkaloids including ajmaline, chandrine, deserpidine, reserpine, rescinnamine, sarpagine, serpentinine, and yohimbine
Viscum: Lectins, phenylpropanoids
Piscidia: Isoflavones, rotenoids, piscidin
Rauwolfia whole plant root 200 mg daily containing 300mcg reserpine a day, European Mistletoe up to 2.5 grams daily, Jamaican Dogwood whole plant 50-400 mg a day
SYNERGISTIC HERBAL FORMULA:
African Snake Root (Rauwolfia), Mistletoe (Viscum), Jamaican Dogwood (Piscidia), Hawthorn (Craaegus), and Motherwort (Leonorus)
SIDE EFFECTS (AND CAUTIONS):
This herbal synergistic formula may interact with anti-hypertensive medications in some patients to cause hypotension and bradycardia. While treating patients with the above herbs, it is important to determine any concomitant anti-hypertensive prescriptions, and to closely monitor blood pressure. Because Rauwolfia contains reserpine, at high doses it can promote or exacerbate Parkinson’s disease. Nasal congestion and diarrhea may occur in patients taking more than 200 mg of Rauwolfia daily. While findings are inconclusive, one study found reserpine to cause depression in 10% of the study patients; however, this percentage is not higher than found in the general population. Some researchers cites Reserpine induced depression as a myth. Rauwolfia, Viscum and Piscidia are not recommended in pregnancy. At higher doses than 2.5 grams a day, there is some evidence that Viscum is contraindicated in Tuberculosis and Aids.
UNSUBSTANTIATED THEORETICAL CONCERNS:
Rauwolfia: There is some theoretical evidence that Rauwolfia should not be taken with alcohol, antipsychotics, antidepressants barbiturates, digoxin, monoamine oxidase inhibitors, propranolol, and stimulant drugs.
Viscum: There is some theoretical evidence that Viscum may decrease effectiveness of immune suppressant drugs.
Piscidia: There is some theoretical evidence this herb should not be taken with central nervous system (CNS) depressant medications.
Editors Note: The first drug studied to be effective in treating depression in a randomized placebo-blind controlled study was reserpine. This study was published in the Lancet in 1955.
Hypertension is a very common medical problem commonly treated with prescription antihypertensive drugs; however, these medications are not without side effects. Additionally, the patients over time often require increased dosage to control blood pressure and/or additional antihypertensive medications. It is recommended that herbal therapy for hypertension be combined with a healthy lifestyle, low-sodium diet, and reduced stress. Lifestyle modifications and herbal treatments can control blood pressure or be added to an antihypertensive protocol. Some herbs can also support, restore and protect cardiac and vascular health.
RAUWOLFIA AND ITS BIOACTIVE CONSTITUENTS
Rauwolfia (in the Apocynaceae family) grows mainly in the tropical forests of Asia and India. The Apocynaceae family is rich in alkaloids and other constituents with important medicinal effects. Rauwolfia contains a large number of bioactive constituents, though most attention has been directed towards the indole alkaloids. These alkaloids are generally classified as either reserpine-like or yohimbine-like. R. serpentina and R. vomitoria contain relatively high concentrations of reserpine. Rauwolfia serpentina is currently considered an endangered herb; it being replaced with the non-endangeredRauwolifa vomitoria in synergistic herbal formulas.
Yohimbine is well known as a selective alpha-adrenergic antagonist in the peripheral blood vessels. Antagonism at these receptors relaxes smooth muscle and lowers blood pressure. Examples of prescription alpha-adrenergic blockers are doxazosin (Cardura) and prazosin (Minipress). Reserpine, on the other hand, acts primarily in the central nervous system at the level of monoamines in the neuronal synapses. Reserpine reduces sympathetic nervous system tone and increases parasympathetic activity via effects on neurotransmittors.
Another principle reserpine-like alkaloid is rescinnamine, which has an antihypertensive effect similar to reserpine. While rescinnamine has a greater hypotensive effect in dogs than reserpine, in humans, it is slightly less potent per gram than reserpine. Deserpidine is structurally related to reserpine (11-demethoxyreserpine) and also has anti-hypertensive effects. Most clinical trials have used deserpidine in combination with a thiazide drug.
Ajmaline (derived from R. serpentine) is a class I antiarrhythmic drug that is highly useful in diagnosing Brugada Syndrome (hereditary cardiac disorder), and differentiating between subtypes of patients with this disease. In fact, administration of the Rauwolfia alkaloid to patients with this type of arrhythmia is known as the “Ajmaline Test”; EKG results of this test are considered to be the best predictor of patients at risk for sudden death from the condition. Ajmaline is a sodium channel blocker that has a short duration of action when given intravenously, which makes it ideal for diagnostic purposes.
THE MEDICINAL EFFECTS OF RAUWOLFIA
Reserpine has been shown to normalize blood pressure, especially in cases of hypertension exacerbated by stress and sympathetic nervous system activity. In fact, prior to the development of beta-blockers, calcium channel blockers, ACE inhibitors, and diuretics, reserpine was a leading therapeutic agent utilized by physicians in the management of hypertension.
Rauwolfia has a mild sedating effect and possible anti-depressant effect; therefore, this herb is especially indicated for those with known concomitant tension or insomnia. However, it is not typically used for exhausted and lethargic patients because it may worsen their fatigue. It is essential to start with a small dose of Rauwolfia to determine if the herb is well-tolerated. Due to its significant side effects, the use of isolated alkaloid reserpine was generally abandoned as other antihypertensive medications became available.
Research in the 1930s and 1940s described the hypotensive effects of Rauwolfia, and its traditional use as a calming and relaxing agent. A Rauwolfia-based medicine for hypertension (Serpasil) was released in the 1950s; several derivatives remain on the market today, and reserpine-based antihypertensive medications are currently used in Russia. A review of randomized, placebo-controlled trials with reserpine concluded that it was an effective tool in the management of hypertension but that additional and larger clinical trials were needed.
Rauwolfia reduces peripheral resistance, thereby lowering blood pressure, and decreases arterial pressure and increases tissue oxygen saturation. The isolated Rauwolfia component (called Ajmaloon in India, from the Sanskrit name for the plant), has a positive effect on blood pressure through its effect on vascular baroreceptors The reserpine alkaloid may also partially block adrenaline receptors.
THE USE OF VISCUM
The Loranthaceae family contains several plant genera including Viscum or ‘Mistletoe’. Several species of Viscum are used worldwide as herbal medicines. Viscum album contains lectins, phenylpropanoids and flavonoids that inhibit cAMP by inducing phosphodiasterase to break down cAMP. The flavonoids include syringin and conferin which may contract the aorta, while kalopanaxin has a relaxing effect. When used in tandem, they have tonifying effects on vascular muscle tone.
An ethanol extract of Viscum album was shown to reduce vascular tension when placed in contact with endothelial tissue. Viscum stimulates both the synthesis and release of nitric oxide to enable vasodilation. Nitric oxide is released from the vascular endothelium, and plays a role in local inflammatory processes; it helps to regulate the degree of vasodilation versus vasoconstriction via a mechanism independent of nerve regulation (such as adrenergic innervation).
Viscum album has been used as a blood pressure-regulating agent in Nigeria. Nigerian researchers reported that Viscum interfered with calcium ion-driven vascular contraction; both the influx of calcium and mobilization of calcium in intracellular stores were believed to be affected. Researchers in Serbia reported that hydroethanol extracts of Viscum album were capable of lowering blood pressure in rats, and that the use of muscarinic receptor blockers diminished or totally abolished the hypotensive effects of Viscum. This suggests that Viscum may act via muscarinic nerve transmission.Likewise, Viscum album has been shown to prevent changes in blood viscosity in a manner that is supportive to maintaining healthy blood pressure.Lectins found in Viscum may affect glycoprotein receptors, erythrocytes, lymphocytes and platelets, and contribute to its positive effects on blood viscosity and blood flow.
Besides blood pressure regulation, Viscum flavonoids may have other cardio-protective effects; it has been shown to reduce tissue damage by inhibiting platelet activating factor (PAF) response and reducing free intracellular calcium ions. Herbal practitioners usually prescribe Viscum as a tincture or tea; few encapsulated products are available on the market. When Viscum is used to treat cancer it is prepared by a different extraction method and given by subcutaneous injection.
THE USE OF PISCIDIA
The physicians in the early 1900’s researched and described Piscidia’s effects on the cardiovascular system; they stated that Piscidia could slow the pulse and briefly increase arterial tension followed by a long reduction in arterial tension. Piscidia was sometimes prescribed as a morphine-substitute to promote restful sleep, because it did not have the numerous side effects associated with morphine.
Piscidia erythrina is a flowering tree in the Fabaceae (legume) family, found in Central America, the West Indies and the Caribbean. It is historically used for pain, tension, insomnia, and to control high blood pressure. Its common name is ‘Jamaican Dogwood’. The linguistic derivation of Piscidia is related to its indigenous historical use as a toxin to stun fish. In fact, the isoflavonoid, sumatrol, and a variety of rotenones are credited with causing fish toxicity and are being investigated as potential chemotherapeutic agents.
Piscidia has powerful effects on the heart, vascular system, respiratory centers and nerve conduction, and is traditionally prescribed in small, doses.Its chemical constituents have not been well-studied; however, it is known to contain the resins, piscidin, jamaicin, and ichthynone. The sum of its chemical constituents are credited with muscle-relaxing effects which could account for its traditional use to treat pain and muscle spasms. Animal studies have also shown an anxiolytic effect that may contribute to its hypotensive actions.
DISCLOSURE OF INTERESTS
Dr. Saunders reports personal fees related to employment or seeing patients from CCNM, the Dundas Naturopathic Centre, and from Beaumont Health Systems, Troy Hospital, MI, outside the submitted work. Dr. Winston reports personal fees from Herbalist & Alchemist, Inc, outside the submitted work. Dr. Stansbury and Dr. Zampieron have nothing to disclose.
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