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Herba Ephedrae
Definition
Herba Ephedrae consists of the dried stem or aerial part of Ephedra sinica
Stapf or other ephedrine-containing Ephedra species (Ephedraceae).
Synonyms
None.
Selected
vernacular names
Amsania, budshur, chewa, Chinese ephedra, ephedra, horsetail, hum, hurna,
joint fir, khama, ma hoang, ma huang, mahuang, mao, maoh, maou, mao-kon,
moc tac ma hoang, mu-tsei-ma-huang, phok, san-ma-huang, shrubby, soma,
song tue ma hoang, trung aa hoang, tsao-ma-huang, tutgantha.
Description
Erect or prostrate, green, almost leafless shrub, 2O-9Ocm high. Branches
erect, short, glaucous green, somewhat flat, 1.0-1.5mm in diameter, with
small sparse longitudinal striae, fasciated at the nodes; nodes reddish
brown; internode 2.5-5.5 cm long X 2 mm in diameter. Small triangular
leaves opposite, reduced to scales, barely 2mm. Flowers in summer, unisexual,
dioecious; male Rowers pedunculate or nearly sessile, grouped in catkins
composed of 4 to 8 pairs of flowers with about 8 anthers; female flowers
biflorous, pedunculate with 3 or 4 pairs of bracts, the naked ovule surrounded
by an un-shaped perianth sheath, fruiting with often fleshy red succulent
bracts, 2-seeded.
Plant
material of interest: stem or aerial part
General appearance
Macroscopically Herba Ephedrae occurs as thin cylindrical or ellipsoidal
cylinder, 1-2mm in diameter; 3.5-5.5cm in length of internode; light green
to yellow-green; numerous parallel vertical furrows on the surface; scaly
leaves at the node portion; leaves, 2-4mm in length, light brown to brown
in colour, usually opposite at every node, adhering at the base to form
a tubular sheath around the stem. Under a magnifying glass, the transverse
section of the stem appears as circle and ellipse, the outer portion greyish
green to yellow-green in colour, and the centre filled with a red-purple
substance or hollow. When fractured at an internode, the outer part is
fibrous and easily split vertically.
Organoleptic
propeties
Odour, slight; taste, slightly bitter and astringent, giving a slight
sensation of numbness on the tongue.
Microscopic
characteristics
The epidermal cells of the stem are covered with a moderately thick granular
cuticle; the cells are polygonal or subrectangular, axially elongated,
having straight anticlinal walls. The stomata are few and are of the ranunculaceous
type with lignified appendages. The epidennis of the scaly leaf is covered
with smooth (upper) or warty (lower) cuticle and consists of subrectangular
to polygonal cells, having straight or sometimes slightly beaded anticlinal
walls; few stomata are present resembling those of stem. The epidermis
of the apical and marginal regions of the scaly leaf shows short papillae-like
outgrowths. Chlorenchymatous palisade-like cells fonn the outer
zone of the cortex; rounded ordinary parenchy-matous cells form the inner
zone of the cortex. Cortical parenchyma and pith cells contain an
amorphous reddish brown substance. Non-lignified or lignified hypodermal
and pericyclic fibres, which have thick walls, bear slit-like pits and
blunt, slightly tapering, occasionally forked ends. The vessels of the
secondary xylem of the stem are lignified with bordered pits, having rounded
or oval apertures. The vessel segments have much inclined end walls, bearing
foraminate perforation plates. The tracheids and fibrous tracheids of
secondary xylem of the stem are lignified with bordered pits having oval
or slit-like apertures. The fibres of the scaly leaf are lignified, usually
irregular or nearly straight, having moderately thick walls and blunt
or sometimes forked ends. Few, small, rounded, simple and compound starch
granules with indistinct hilum are present in cortical parenchyma, pith,
and medulary ray cells. Few, small prisms of calcium oxalate are present
in the cortical parenchyma.
Powdered
plant material
Powdered Herba Ephedrae is greyish green. Numerous thick fragments of
cutinized outer walls of epidermis vary from colourless to varying shades
of brown or red; numerous fragments of sclerenchyma fibres with extremely
thickened, non-lignified to lignified walls, narrow, frequently indistinct
lumina and sharp pointed ends; fragments of vascular tissue showing tracheids
with bordered pores and occasional spiral and pitted tracheae; numerous
chlorenchyma cells; starch grains simple, spheroidal to occasionally ovate,
averaging up to 1.2 cm but occasionally up to 20cm; fragments of epidermis
with rectangular cells and granular contents, some with sunken elliptical
stomata; fragments of lignified or non-lignified pith parenchyma, some
of the cells showing mucilage sacs; papillae; granules of calcium oxalate.
Geographical
distribution
Ephedra species are found in Afghanistan, Central America. China, India,
regions of the Mediterranean, Mongolia, and North America.
General
identity tests
Macroscopic and microscopic examinations and microchemical tests fot the
presence of alkaloids with Mayer's reagent.
Purity
tests
Microbiology
The test for Salmonella spp. in Herba Ephedrae products should be negative.
The maximum acceptable limits for other microorganisms are as follows.
For preparation of decoction: aerobic bacteria-not more than 10 /g; fungi-not
more than 10-5/g; Escherichia coli-not more than 10-2/g. Preparations
for internal use: aerobic bacteria-not more than 10-5 /g or ml; fungi-not
more than 10-4/g or ml; enterobacteria and certain Gram-negative bacteria-not
more than 10-5/g or ml; Escherichia coli-0/g or ml.
Foreign
organic matter
Woody stems, not more than 5%. Does not contain stems of Equisetaceae
or Gramineae plants, nor any other foreign matter.
Total
ash
Not more than 9% .
Acid-insoluble
ash
Not more than 2%.
Moisture
Not more than 9%.
Pesticide
residues
To be established in accordance with national requirements. Normally,
the maximum residue limmit of aldrin and dieldrin for Herba Ephedrae is
not more than 0.05 mg/kg. For other pesticides, see WHO guidelines on
quality control methods for medicinal plants and guidelines for predicting
dietary intake of pesticide residues.
Heavy
tttetals
Recommended lead and cadmium levels are no more than 10 and 0.3mg/kg,
respectively, in the final dosage form of the plant material.
Radioactive
residues
For analysis of strontium-90, iodine-131, caesium-134, caesium-137, and
plutonium-239, see WHO guidelines on quality control methods for medicinal
plants.
Other
purity tests
Chemical, dilute ethanol-soluble extractive, and water-soluble extractive
tests to be established in accordance with national requirements.
Chemical
assays
Contains not less than O.7%, total alkaloids, calculated as ephedrine
by high-performance liquid chromatography in the Japanese pharmacopoeia;
or not , less than 0.8% of total alkaloids, calculated as ephedrine in
the Chinese pharmacopoeia. Thin-layer,
gas-liquid or high-performance liquid chromatographic analysis for ephedrine
and related alkaloids are available.
Major
chemical constituents
The major active principle found in Herba Ephedrae is ( -)-ephedrine in
concentrations of 40-90% of the total alkaloid fraction, accompanied by
( +) -pseudoephedrine. Other trace alkaloids in the alkaloid complex include
( -)-norephedrine, ( + )-norpseudoephedrine, ( -)-methylephedrine and
( + )- methylpseudoephedrine. The total alkaloid content can exceed 2%
depending on the species. Not all Ephedra species contain ephedrine or
alkaloids.
Dosage
forms
Powdered plant material; extracts and other galenicals. Store in well
closed, light-resistant containers.
Medicinal
uses
Uses supported by clinical data
Herba Ephedrae preparations are used in the treatment of nasal congestion
due to hay fever, allergic rhinitis, acute coryza, common cold, and sinusitis.
The drug is further used as a bronchodilator in the treatment of bronchial
asthma.
Uses described in
pharmacopieias an din traditional systems of medicine
Herba Ephedrae has been used for the treatment of urticaria, enuresis,
narcolepsy, myasthenia gravis, and chronic postural hypotension.
Uses described in
folk medicine, not supported by experimental or clinical data
Other medical uses claimed for Herba Ephedrae preparations include its
use as an analgesic, an antiviral agent, an antitussive and expectorant,
an antibacterial, and an immune stimulant.
Clinical
pharmacology
Two of the main active constituents of Herba Ephedrae, ephedrine and pseudoephedrine,
are potent sympathomimetic drugs that stimulate a-, ß1- and ß2-
adrenoceptors. Pseudoephedrine's activity is similar to ephedrine, but
its hypertensive effects and stimulation of the central nervous system
are somewhat weaker. Part of ephedrine's peripheral action is due to the
release of norepinephrine, but the drug also directly affects receptors.
Tachyphylaxis develops to its peripheral actions, and rapidly repeated
doses become less effective owing to the depletion of norepinephrine stores.
Cardiovascular
actions
Like epinephrine (adrenaline), ephedrine excites the sympathetic nervous
system, causing vasoconstriction and cardiac stimulation. Ephedrine differs
from epinephrine in that it is orally active, has a much longer duration
of action, and has more pronounced activity in the central nervous system,
but is much less potent . The drug stimulates the heart rate, as well
as cardiac output, and increases peripheral resistance, thereby producing
a lasting rise in blood pressure. The cardiovascular effects of ephedrine
persist up to ten times as long as those of epinephrine. Ephedrine elevates
both the systolic and diastolic pressures and pulse pressure. Renal and
splanchnic blood flows are decreascd, while coronary, cerebral, and muscle
blood flows are increased.
Bronchodilator
and nasal decongestant
Ephedrine, like epinephrine, relaxes bronchial muscles and is a potent
bronchodilator owing to its activation of the ß-adrenoceptors in
the lungs. Bronchial muscle relaxation is less pronounced but more sustained
with ephedrine than with epinephrine. As a consequence, ephedrine should
be used only in patients with mild cases of acute asthma and in chronic
cases that require maintenance medication. Ephedrinc, like other sympathom\metics
with a receptor activity, causes vasoconstriction and blanching when applied
topically to nasal and pharyngeal mucosal surfaces. Continued, prolonged
use of these preparations (>3 days) may cause rebound congestion and
chronic rhinitis . Both ephedrine and pseudoephedrine are useful orally
as nasal decongestants in cases of allergic rhinitis, but they may not
be very effective for the treatment of nasal congestion due to colds.
Central
nervous system
Mydriasis occurs after local application of ephedrine (3-5%) to the eye,
but the effect lasts for only a few hours. Ephedrine is of little value
as a mydriatic in the presence of inflammation. The activity of the smooth
muscles of the uterus is usually reduced by ephedrine; consequently, the
drug has been used to relieve the pain of dysmenorrhoea.
Ephedrine is a potent stimulator of the central nervous system. The effects of the drug may last for several hours after oral administration. Thus, preparations containing Herba Ephedrae have been promoted for use in weight reduction and thermogenesis (fat burning). The safety and effectiveness of these preparations is currently an issue of debate and requires further investigation.
Ephedrine stimulates the a-adrenoceptors of the smooth muscle cells of the bladder base, which increases the resistance to the outflow of urine. Thus Herba Ephedrae has been used in the treatment of urinary incontinence and nocturnal enuresis.
Contraindications
Herba Ephedrae should not be administered to patients with coronary thrombosis,
diabetes, glaucoma, heart disease, hypertension, thyroid disease, impaired
circulation of the cerebrum, phaeochromocytoma, or enlarged prostate .
Co-administration of Herba Ephedrae preparations with monoamine oxidase
inhibitors is contraindicated as the combination may cause severe, possibly
fatal, hypertension.
Warnings
Dosage should be reduced or treatment discontinued if nervousness, tremor,
sleeplessness, loss of appetite or nausea occurs. Not for children under
6 years of age. Keep out of the reach of children. Continued, prolonged
use may cause dependency.
Precautions
General
Insomnia may occur with continued use of Herba Ephedrae preparations.
Drug
interactions
In combination with cardiac glycosides or halothane, may cause heart rhythm
disturbances; with guanethidine, may cause an enhancement of sympathomimetic
effect; with monoamine oxidase inhibitors, can cause severe, possibly
fatal, hypertension; with ergot alkaloid derivatives or oxytocin. may
increase risk of high blood pressure.
Caricinogenesis,
mutagenesis, impairment of fertility
Extracts of Ephedra sinica are not mutagenic in the Salmonella microsome
reversion assay.
Pregnancy:
teatogenic effects
Ephedra sinica did not have any teratogenic effects in vivo.
Pregnancy:
nonteratogenic effects
Ephedra sinica is not abortifacient in rats. Clinical studies in
humans are not available; therefore, use of the drug during pregnancy
is not generally recommended.
Nursing
mothers
There are no reliable studies on this subject. Therefore, nursing mothers
should not take Herba Ephedrae without consulting a physician.
Paediatric
use
Herba Ephedrae should not be administered to children under 6 years of
age.
Other
precautions
No information available concerning drug and laboratory test interactions.
Adverse
reactions
In large doses Herba Ephedrae products can cause nervousness, headaches,
insomnia, dizziness, palpitations, skin flushing and tingling. and vomiting.
The principal arlverse effects of ephedrine and Herba Ephedrae are stimulation
of the central nervous system, nausea, tremors, tachycardia, and urine
retention. Continued, prolonged use (>3 days) of topical preparations
containing Herba Ephedrae, for the treatment of nasal congestion, may
cause rebound congestion and chronic rhinitis. Continued prolonged use
of oral preparations may cause dependency.
Posology
Crude plant material: 1-6g for decoction daily. Liquid extract (1:1
in 45% alcohol): 1-3ml daily. Tincture (1:4 in 45% alcohol): 6-8ml
daily.