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Ephedra |
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Ephedra (English) Ephedra sinensis
(Botanical) Ephedraceae (Plant Family)
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Overview |
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Native to central Asia, Ephedra sinensis (also called ma huang) has
been used in Traditional Chinese Medicine for more than 5,000 years. It is
primarily a remedy for bronchial asthma but also prescribed for symptoms of cold
and flu, including fever, chills, cough wheezing, headache, and nasal
congestion. It is the most widely used herbal medicine with known efficacy in
the treatment of bronchial asthma.
While several species of ephedra are distributed throughout the world,
Ephedra sinica, or Chinese ephedra, is particularly potent in alleviating
asthmatic symptoms. Pharmacological studies show that ephedra and ephedrine, the
main active constituent of ephedra, is a central nervous system stimulant. This
compound induces bronchodilation and vasoconstriction, and it decreases
bronchial edema. Ephedra is also sold commercially as a weight-loss aid,
although the evidence for its effectiveness in treating obesity is
contradictory.
Adverse side effects such as elevated blood pressure and heart rate are
associated with ephedra. In addition, ephedrine can be used as a precursor for
synthesizing methamphetamine, an illegal drug. These potential risks associated
with the sale and use of ephedra have prompted some states in the United States
to pass laws regulating the sale of the herb and preparations derived from it.
In reality, however, experts agree that the vast majority of ephedrine products
currently available are not derived from ephedra, but instead are chemically
synthesized from L,1-phenyl-1-acetylcarbinol and methylamine.
Since the 1980s, ephedra has been the center of major controversy between the
nutritional supplement industry and the U.S. Food and Drug Administration (FDA).
Concerns have been raised over the use of this herb as a weight-loss agent,
central nervous system stimulant, athletic performance enhancer, and substitute
for illegal "street" drugs. In response to these concerns, the American Herbal
Products Association in 1994 disseminated a warning label for consumers about
the adverse side effects of ephedra. Following the lead of the FDA, the herb
industry specified standards for ephedra products. These standards call for a
limit on the intake of ephedra preparations of 25 mg total alkaloids per dose
and a total daily consumption of 100 mg of ephedra.
In 1997, the FDA issued further regulations governing the formulations of
ephedra products. However, other agencies have challenged the foundation of the
FDA's recommendations. While the U.S. General Accounting Office (GAO) conceded
that the FDA was justified in evaluating the safety of ephedra products, the GAO
also questioned the cost-benefit analysis used by the FDA to guide its decision.
Earlier research revealed that caffeine and aspirin, either separately or in
combination, potentiated the appetite-suppressant, thermogenic (heat-promoting),
and athletic-enhancing effects of ephedra. More recent findings, however,
indicate that this herb, when administered singly and devoid of either caffeine
or aspirin, is safe for individuals with normal blood
pressure. |
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Macro Description |
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Ephedra is a genus of dioecious, perennial evergreens. These erect, highly
branching subshrubs can reach a height of four feet. Virtually leafless, ephedra
is typically found on tundra as well as rocky and sandy slopes. It is
distinguished by its cylindrical, slender, yellow-green branches and
under-runners. Its prostate stems have vertical grooves and are gray-green to
pale green in color.
The small, reddish-brown leaves that radiate from the nodes are toothed at
the tips, sometimes forming pointed scales. The yellowish-green flowers are so
small and inconspicuous that they appear in terminal catkins as acurninate
scales. Male and female flowers bloom separately. In August, the female flowers
bear poisonous, fleshy red cones resembling berries. These are known as ephedra,
or seagrapes. |
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Part Used/Pharmaceutical
Designations |
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Young stems, branchlets |
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Constituents/Composition |
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2-aminophenylpropane-type alkaloids, primarily L-(-)-ephedrine (IR,2S-(-)-
ephedrine and D-pseudoephedrine (IS,2S-(+)- ephedrine); lesser alkaloids
L-norephedrine, D-norpseudoephedrine; flavonoid glycosides; glycans (ephedrans);
citric, malic, and oxalic acids; proanthocyanidins (condensed tannins); tannins;
volatile oils (1-alpha-terpineol, limonene, linalool). |
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Commercial
Preparations |
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Chinese ephedra is available as dried and liquid preparations derived from
the dried young herbaceous stems and branchlets of Ephedra sinica
harvested in the fall. Products typically have a minimum of 0.8% total alkaloid
content, calculated as ephedrine. Some ephedra preparations are made from E.
equisetina, E. intermedia, and other species containing ephedrine.
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Medicinal
Uses/Indications |
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Traditional uses: Bronchial asthma, cold, flu, fever, chills, lack of
perspiration, headache, nasal congestion, aching joints and bones, and
cough.
Conditions: Cough, bronchitis, bronchial secretion, mild forms of airway
disease (especially those resulting from spastic disorders), allergic rhinitis,
sinusitis.
Clinical applications: Diseases of the respiratory tract with mild
bronchospasms in adults and children over the age of 6; bronchodilators in the
treatment of mild to moderate asthma; hay fever; common cold; weight-loss aid.
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Pharmacology |
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Chemically similar to epinephrine, ephedrine functions indirectly as a
sympathomimetic drug, both accelerating and enhancing the intensity of
respiration. Its stimulatory effects on the heart induce cardiac
automaticity.
In in vivo studies, both ephedrine and ephedra extracts inhibited tracheal or
bronchial mucosa-induced coughing in anesthetized animals. The bronchodilating
and antitussive actions of ephedrine account for suppression of the cough
reflex. These effects are due to the stimulant activity of ephedrine on the
central nervous system. There is also evidence that ephedra exhibits peripheral
vasoconstricting effects. The activity of pure (-)-ephedrine is more potent than
that of whole-herb extracts.
In other animal experiments, ephedra increased the endurance of rodents on
immobilization and coldness tests. Administered singly, ephedrine induced weight
loss and reduction in body fat through thermogenesis in vivo.
However, clinical studies on the effects of ephedrine on loss of weight and
body fat are conflicting. While ephedrine appears to be efficacious for weight
loss in individuals with thermogenic deficiencies, it is not effective in people
whose basal metabolic rates are not impaired. In other human investigations,
ephedra extracts increased T-lymphocytes in healthy subjects. An aqueous
decoction and volatile oil showed diaphoretic properties in
humans. |
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Dosage Ranges and Duration of
Administration |
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- Infusion or decoction: 1.2 to 2.3 g in 150 ml water
- Fluid extract (1:1): 1.2 to 2.3 ml
- Tincture 1:5 (g/ml): 5.75 to 11.5 ml
The maximum dose for children is 2 mg/kg body weight. Ephedra products should
be used only on a short-term basis for up to three months. A repeated course is
feasible. However, prolonged use carries a risk of tachyphylaxis and addiction.
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Side
Effects/Toxicology |
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Ephedra can produce adverse side effects of irritability, motor restlessness,
insomnia, headaches, nausea, vomiting, and urinary complaints. Excessive dosing
can induce tachycardia, cardiac arrhythmia, palpitations, and drug dependency.
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Warnings/Contraindications/Precautions |
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Ephedra is contraindicated in patients who have anxiety, restlessness,
hypertension, narrow-angle glaucoma, cerebral circulatory impairment, prostatic
adenoma with residual urine accumulation, thyrotoxicosis, and diabetes. It is
also contraindicated for individuals taking antihypertensives or antidepressant
therapy. |
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Interactions |
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While no specific drug interactions have been reported for the herb, the
active ingredients of ephedra, ephedrine and pseudoephedrine, have several
documented interactions with monoamine oxidase inhibitors (Dingemanse 1993;
Dingemanse et al. 1996); tricyclic antidepressants (Boada et al. 1999); narcotic
analgesics (Dambisya et al. 1991); antihypertensive medications (particularly
clonidine) (Goyagi et al. 1998; Hayakawa-Fujii et al. 1999); xanthine
derivatives such as theophylline and caffeine (Bahner et al. 1993; Dawson et al.
1995; Heiss and Podreka 1978); aspirin (Horton and Geissler 1991); and
amphetamine-derivatives (Clarkson and Thompson 1997). The isolation of
individual ingredients from a complex compound is not necessarily equivalent to
testing the complete product; however, for safety, it is important to assume
that interactions with the herb may be similar.
Ephedra should not be used with prescription or over the counter medications
containing ephedrine, pseudoephedrine, or phenylpropanolamine, which are
ingredients found commonly in nasal decongestants and weight loss
products. |
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Regulatory and Compendial
Status |
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Internal use of ephedra is approved by the German Commission E for diseases
of the respiratory tract with mild bronchospasms in adults and children over the
age of 6. |
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References |
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Copyright © 2000 Integrative Medicine
Communications This publication contains
information relating to general principles
of medical care that should not in any event be construed as specific
instructions for individual patients. The publisher does not accept any
responsibility for the accuracy of the information or the consequences arising
from the application, use, or misuse of any of the information contained herein,
including any injury and/or damage to any person or property as a matter of
product liability, negligence, or otherwise. No warranty, expressed or implied,
is made in regard to the contents of this material. No claims or endorsements
are made for any drugs or compounds currently marketed or in investigative use.
The reader is advised to check product information (including package inserts)
for changes and new information regarding dosage, precautions, warnings,
interactions, and contraindications before administering any drug, herb, or
supplement discussed herein. | |