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Plant Poisoning, Alkaloids - Tropane

Author: Richard A Wagner, MD, PhD, Staff Physician, Sierra Vista Regional Health Center; Consultant, Arizona Drug and Poison Information Center
Coauthor(s): Samuel M Keim, MD, Associate Professor, Department of Emergency Medicine, University of Arizona College of Medicine
Contributor Information and Disclosures

Updated: Dec 11, 2007

Introduction

Background

Alkaloids are plant metabolites that have a nitrogen-containing chemical ring structure, alkali-like chemical reactivity, and pharmacologic activity. The alkaloids represent a very diverse group of medically significant compounds that include well-known drugs like the opiates.

A subgroup of the alkaloids is the alkaloid amines. The 3 major pharmacologic groups of alkaloid amines are the hallucinogenic alkaloid amines, the stimulant alkaloid amines, and the highly anticholinergic tropane alkaloids (also called the belladonna alkaloids or bicyclic alkaloids).

Plants that contain the tropane alkaloids atropine, scopolamine, and hyoscyamine include the following:

• Datura species (jimson weed, angel's trumpet, thorn apple)
• Hyoscyamus niger (henbane)
• Atropa belladonna (deadly nightshade)
• Mandragora officinarum (mandrake)

All of these plants have long histories of hallucinogenic use and have been connected with sorcery, witchcraft, native medicine, and magico-religious rites dating back to 1500 BC and Homer's Odyssey. (Homer's use of the plant moly as an antidote to Circe's poisonous anticholinergic drugs may have been the first recorded use of an anticholinesterase to reverse central anticholinergic intoxication.)

Chinese herbal medicines containing tropane alkaloids have been used to treat asthma, chronic bronchitis, pain, and flu symptoms. In Mexico, Datura is taken by Yaqui women to lessen pain of childbirth. In Africa, a common use is to smoke leaves from Datura to relieve asthma and pulmonary problems. Many cultures worldwide add plants with tropane alkaloids (particularly Datura species) to alcoholic beverages to increase intoxication.

Recently, Datura has been used as a recreational hallucinogen in the US, resulting in sporadic cases of anticholinergic poisoning and death. Numerous cases of anticholinergic poisoning also have resulted from belladonna alkaloid contaminants in foods, including commercially purchased Paraguay tea (an herbal tea derived from Ilex paraguariensis), hamburger, honey, stiff porridge made from contaminated millet, and homemade "moon flower" wine. Other accidental ingestions include misuse as an edible wild vegetable and inclusion in homemade toothpaste, as well as a large epidemic in New York and the eastern US that resulted from heroin contaminated with scopolamine.

Although most tropane alkaloids cause an anticholinergic syndrome, a recent report indicates that the tropane alkaloid–containing medicinal herb Erycibe henri Prain ("Ting Kung Teng") contains a tropane alkaloid that may cause a cholinergic syndrome, as well as renal, hepatic, and erythrocyte toxicity. This is considered atypical for the tropane alkaloids, which are predominantly strongly anticholinergic.

Pathophysiology

Toxicity from plants containing tropane alkaloids manifests as classic anticholinergic poisoning. Symptoms usually occur 30-60 minutes after ingestion and may continue for 24-48 hours because tropane alkaloids delay gastric emptying and absorption.

Scopolamine, acting as an antagonist at both peripheral and central muscarinic receptors, is thought to be the primary compound responsible for the toxic effects of these plants. Tropane alkaloids are found in all parts of the plants, with highest concentrations in roots and seeds.

Atropine is an artifact of purification, produced by racemization of l-hyoscyamine. The proportion of each alkaloid present varies among species, time of year, location, and part of plant. As little as one-half teaspoon of Datura seed, equivalent to 0.1 mg of atropine per seed, has caused death from cardiopulmonary arrest. The usual route of ingestion is as a tea, although ingesting seeds or other plant parts and smoking dried leaves also are common.

Frequency

United States

Incidence is sporadic, with clusters of poisoning cases, mostly among adolescents using plants for their hallucinogenic effects. 

During 2005, 975 anticholinergic plant poisonings were reported to Poison Control Centers in the United States; 566 of these cases were treated in health care facilities.¹

During 1998-2004, a total of 188 reported human exposures were identified by Texas Poison Control Centers.² Seventy-six percent of the exposures occurred in June-October, 82% of the cases occurred in males, and 72% of cases occurred in those aged 13-19 years.

Widespread access to information on hallucinogenic plants through the Internet may lead to a further increase in the incidence.

International

Worldwide incidence is unknown. However, cases have been reported in Germany, Italy, Greece, Saudi Arabia, Tanzania, Australia, Brazil, Hong Kong, Taiwan, Mexico, Chile, and Venezuela, attesting to broad geographic distribution of Datura species.

Mortality/Morbidity

Nonfatal cases are likely underreported.

• Of the 975 anticholinergic plant poisonings reported to the American Association of Poison Control Centers in 2005, there were no fatalities.¹
• In 1993, 318 cases of Datura poisoning were reported to the American Association of Poison Control Centers; the Centers for Disease Control and Prevention (CDC) reported 2 deaths.
• In 1994, the CDC reported 7 cases of anticholinergic poisoning in 3 families who consumed contaminated commercial Paraguay tea.
• Reports of sporadic cases or clusters of cases involving intentional use as a hallucinogen are frequent; most patients recover uneventfully, although fatalities do occur.
• Related deaths from drowning, exposure, and lack of supportive care have been reported.

Sex

Males are more frequently involved in cases of intentional exposure.

Age

No age predilection exists, although Datura use as a recreational drug is more common among adolescents. Accidental ingestion and resultant toxicity in children has been reported.

Clinical

History

• As in any patient presenting with an acute change in mental status or suspected poisoning, attempt to obtain the following information:
  • Complete past medical history
  • Medication history
  • Precise description or sample of suspected toxicant(s)
  • Route of administration, amount ingested, time since ingestion, and reason for ingestion
  • Co-ingestants and use of alcohol or other street drugs
• Initial signs and symptoms may include the following:
  • Dry mucous membranes and skin
  • Dysphagia and dysarthria
  • Photophobia
  • Blurred vision
  • Tachycardia
  • Urinary retention
• Initial signs and symptoms may be followed by hyperthermia, confusion, agitation, combativeness, seizures, coma, and death.
• Amnesia regarding events following ingestion of tropane alkaloids is common.
• Identification of ingested plants can be diagnostic of tropane alkaloid poisoning.
  • Datura species, the most commonly encountered plants containing tropane alkaloids, are 3-5 foot annuals with coarse-toothed leaves.
  • Trumpet-shaped flowers are 3-5 inches in length, with white-pale-violet colored petals (see Media files 1-2).
  • Most important for taxonomic identification are spiny, round, chambered seed pods (see Media file 3).

Physical

The mnemonic "red as a beet, dry as a bone, blind as a bat, mad as a hatter, and hot as a hare" is useful to remember the anticholinergic toxidrome.

• Vital signs
  • Tachycardia and tachypnea
  • Hyperpyrexia (in about 20% of cases)
  • Inconsistent hypertension and hypotension, respiratory depression (rare)
  • Warm dry skin (may be flushed)
• Head, ears, eyes, nose, and throat
  • Mydriasis and cycloplegia (almost always occur and may persist for days)
  • Dry mucous membranes
• Abdomen
  • Diminished bowel sounds
  • Distention of urinary bladder
• Neurologic
  • Agitation, confusion, and hallucinations
  • Seizures, decreased muscle coordination, paralysis, respiratory depression, and coma (rare)

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