Hellebore, American Description - Side Effects and its Dosage
Taxonomic class: Liliaceae
Common Trade Names: Cryptenamine
Common Forms: Available as fluidextract, powder, root, and tincture.
American or green hellebore is derived from the dried rhizome and roots of the perennial herb Veratrum viride. Related species include V. album (white hellebore), V. californicum, V. japonicum, and V. officina Ie (Cevadilla).
The main components of the root include several ester glycoalkaloids (pseudojervine, rubijervine, jervine, neogermitrine, cevadine, protoveratrine, veratridine, and protoveratridine), starch, and resin. The alkaloids are chemically similar to steroids and are considered both medicinally active and toxic. All species contain varying amounts of alkaloids, which explains the varying degrees of action and toxicity.
The ester alkaloids are responsible for hellebore's physiologic effects, including lowering arterial pressure and heart and respiratory rates and stimulating blood flow to the kidneys, liver, and extremities. The CV response to Veratrum alkaloids depends on the agent and the dose administered. High doses have paradoxically elevated blood pressure .
Veratrum alkaloids are known to have a depolarizing action on cardiac tissue, nerve membranes, and skeletal and visceral muscles. They are believed to increase nerve and muscle excitability, as noted by the adverse effects of increased muscle tone and paresthesia. These agents also produce nausea and emesis; large doses depress respiration and can cause respiratory failure.
Historically, hellebore has been used as an emetic and for neuralgias, peritonitis, pneumonia, and seizures. More recently, Veratrum alkaloids have been used to treat hypertension, acute hypertensive crises, hypertensive toxemia of pregnancy, and nephropathies . They have been given parenterally (with success) for managing pulmonary edema resulting from severe acute hypertensive crises. One Veratrum alkaloid, germine diacetate, has been used experimentally to treat myasthenia gravis .
Hellebore and the Veratrum alkaloids are not currently used because of their narrow therapeutic index and highly toxic nature. Some herbalists may recommend American or green hellebore as a cardiac sedative. Dosage
For cardiac sedation, 1 to 3 minims of fluidextract P.O. every 2 to 3 hours until pulse rate is reduced; or 1 to 2 grains of powder P.O.; or 10 to 30 minims of tincture P.O. I.V. doses are unknown.
CNS: paresthesia, seizures, syncope.
CV: arrhythmias, bradycardia, ECG changes, hypertension, hypotension.
EENT: dysgeusia, extraocular muscle paralysis, increased salivation, sneezing (inhalation).
GI: abdominal pain and distention, nausea, vomiting.
Musculoskeletal: increased muscle tone, muscle weakness.
Respiratory: dyspnea, respiratory depression.
Skin: pallor, sweating.
Interactions: None reported.
Contraindications and precautions
American hellebore is contraindicated in patients with aortic coarctation, digitalis intoxication, hypotension, increased intracranial pressure (unless caused by hypertensive crisis), or pheochromocytoma and in pregnant patients.
American hellebore is considered highly toxic. It has a low therapeutic index that makes it unfavorable for medicinal purposes.
Alert Ingestion of any part of the plant can cause toxicity. Signs of overdose are abdominal pain, burning in throat, diarrhea, loss of consciousness, nausea, paralysis, shortness of breath, spasms, syncope, and vision changes. Most cases have not been fatal because of the rapid vomiting that occurs and the poor intestinal absorption of the Veratrum alkaloids.
Although no known chemical interactions have been reported in clinical studies, consideration must be given to the pharmacologic properties of the herbal product and the potential for exacerbation of the intended therapeutic effect of conventional drugs.
Advise the patient to consult a health care provider before using herbal preparations because a treatment that has been clinically researched and proved effective may be available.
Points of Interest
Veratrine, which once appeared in the USP and British Pharmacopoeia Codex, is derived from the plant V. officina Ie (Mexican hellebore) or sabadilla. It is used as a topical analgesic and a parasiticide. Veratrine contains many of the same alkaloids found in American hellebore in varying amounts.
Ingestion of the plant V. californicum, related to American hellebore, has been associated with causing cyclopia and other related facial deformities in animals.
Sneezing powders are known to have contained Veratrum alkaloids. The powders contained pulverized V. album root, which, when inhaled, caused many of the same adverse effects seen after ingestion, including bradycardia, hypotension, nausea, sweating, and vomiting .
Veracintine, an alkaloid isolated from V. album, and its derivatives have exhibited in vitro cytotoxic effects on leukemia cells.
Despite its extensive use in the past for malignant hypertension, hellebore and Veratrum alkaloids are no longer preferred for these uses because of their narrow therapeutic index and the emergence of safer and more tolerable agents. The Veratrum alkaloids have clear pharmacologic activity, but their noxious and toxic adverse effects have limited their use. Because only small amounts of Veratrum alkaloid extracts are needed to cause toxic effects, their use is considered extremely dangerous. Hellebore is not recommended for medicinal use.
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