Parasympathomimetic Herbs

Summary

Parasympathomimetic Herbs

introduction:
Very few common medicinal herbs have overtly cholinergic constituents that produce overall physiological parasympathomimetic action. The exceptions are restricted herbs, poisons, or foods not generally used in herbal medicine, such as the pilocarpine-containing Pilocarpus spp. (Jaborandi) and muscarine from Amanita muscaria and related toxic mushroom species. The Asian masticatory spice Areca catechu contains the muscarinic alkaloid arecoline, which is also nicotinic at higher doses. Areca is not used therapeutically in Western herbal medicine although the isolated alkaloids have been shown to cause bronchoconstriction and may exacerbate extrapyramidal effects of neuroleptic drugs.

Several western herbs are considered "parasympathomimetic-like" by herbalists primarily because of cardiovascular effects that resemble muscarinic cholinergic activity (hypotension, bradycardia). The pharmacology of these agents is either unknown, or results from complex mechanisms other than direct muscarinic agonism. For example, the veratrum alkaloids of Veratrum spp. (Liliaceae) have some cholinergic activity but their predominant bradycardic and hypotensive actions are more due to sodium channel blocking.

overview of interactions:
• herbal/food constituent possibly affecting drug performance: Antiasthmatics

• herbal constituent theoretically affecting drug performance: Atropine
Note: Parasympathomimetic herbs may antagonize antimuscarinic drugs such as atropine and hyoscamine.

• herbal constituent affecting drug performance and toxicity: Procyclidine (Kemadrin®)

• herbal synergy:
Indirect interaction with other herbs in the following groups may take place through various synergistic physiologic mechanisms including:
• Sedative Herbs
• Hypotensive and Bradycardic Herbs
• Vasodilator Herbs




Herbs

herbal constituent affecting drug performance: Antiasthmatics

• mechanism: Due to muscarinic effects on bronchial smooth muscle, isolated arecoline alkaloid challenge causes bronchoconstriction and therefore may reduce the effectiveness of some classes of antiasthmatic medications.
(Taylor RFH, et al. Lancet 1992;339:1134-1136.)

• herbal/dietary concern: Individuals prone to asthma, and those taking asthma medications should avoid excessive consumption of Areca catechu (Betel Nut). Betel nut is little used in Western herbal medicine, although large amounts are consumed in India and South East Asia and it is similarly consumed by ethnic populations from these cultures now resident in the West.

herbal constituent theoretically affecting drug performance: Atropine

• mechanism: Parasympathomimetic (cholinerginic) herbs will theoretically antagonize antimuscarinic drugs such as atropine and scopalamine.

• herbal concern: Due to the relatively weak cholinergic activity of the great majority of herbal paraympathomimetics this interaction is speculative and unlikely to occur in daily practice.

herbal/dietary constituent affecting drug performance and toxicity: Procyclidine (Kemadrin®)

• report: Deahl reported two cases of schizophrenic patients maintained on depot procyclidine developing severe extrapyramidal symptoms (tremor, stiffness, akithesia) following excessive betel nut consumption.
(Deahl M. Mov Disord 1989;4:330-333.)

• herbal/dietary concern: Excessive consumption of Areca should be avoided during therapy with neuroleptic drugs affecting cholinergic transmission.


Common herbs with parasympathomimetic activity:
See "Parasympathomimetic-like" below.

Restricted and unusual herbs with parasympathomimetic activity:
• Areca catechu (Betel nut), containing arecoline.
• Pilocarpus jaborandi (Jaborandi), containing pilocarpine.
• Veratrum album (White Hellebore), containing veratramine.
• Veratrum viride (American Hellebore), containing veratramine.
• Lobelia inflata (Lobelia), containing lobeline, has nicotinic cholinergic effects and produces mixed autonomic responses as opposed to the muscarinic alkaloids.
• Nicotinia tabacum (Tobacco), containing nicotine.

"Parasympathomimetic-like" herbs:
• Anemone spp. (Pulsatilla)
• Rauwolfia serpentina (Indian Snakeroot), containing reserpine, is sympatholytic, i.e., it depletes central and peripheral catecholamines.* toxic

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Do not rely solely on the information in this article.

The information presented in Interactions is for informational and educational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, case reports, and/or traditional usage with sources as cited in each topic. The results reported may not necessarily occur in all individuals and different individuals with the same medical conditions with the same symptoms will often require differing treatments. For many of the conditions discussed, treatment with conventional medical therapies, including prescription drugs or over-the-counter medications, is also available. Consult your physician, an appropriately trained healthcare practitioner, and/or pharmacist for any health concern or medical problem before using any herbal products or nutritional supplements or before making any changes in prescribed medications and/or before attempting to independently treat a medical condition using supplements, herbs, remedies, or other forms of self-care.


References

Deahl M. Betel nut-induced extrapyramidal syndrome: an unusual drug interaction. Mov Disord 1989;4:330-333.
Abstract: Two cases are described of chronic schizophrenic patients maintained on depot neuroleptics, who developed severe extrapyramidal symptoms following a period of heavy betel nut consumption. A mechanism for this effect is proposed based on the pharmacological antagonism of the anticholinergic agent, procyclidine, by the active alkaloid ingredient of the betel, arecoline.

Hardman J, et al. eds. Goodman and Gilman's Pharmacological Basis of Therapeutics. Ninth Edition. McGraw Hill, 1996

Moore M. Herbal/Medical Contraindications. Albuquerque, NM: Southwest School of Botanical Medicine, 1995.

Taylor RFH, Al-Jarad N, John LME. Betel-nut chewing and asthma. Lancet 1992; 339:1134-1136.
Abstract: Two Asian patients admitted to hospital with acute severe asthma had been chewing betel nut immediately before the attacks. Arecoline, a cholinergic alkaloid, is a major constituent of Areca catechu (betel) nut and causes the euphoric effects. We sought an association between betel-nut chewing and bronchoconstriction in asthmatic patients. In vitro, arecoline caused dose-related contraction of human bronchial smooth-muscle strips, with one-tenth the potency of methacholine. In a double-blind challenge study, inhalation of arecoline caused bronchoconstriction in six of seven asthmatic patients and one of six healthy subjects; methacholine caused bronchoconstriction in all the asthmatic patients and in five controls. The geometric mean concentrations of arecoline and methacholine that caused 20% falls in the forced expiratory volume in 1 s (PC20 FEV1) in the asthmatic subjects were 5.2 mg/ml and 1.6 mg/ml, respectively. We then studied four Bengali asthmatic patients, regular users of betel nut, during a betel-nut challenge. Three showed no adverse effects, but one showed a 30% fall in FEV1 by 150 min after chewing; the effect was reproducible. In the UK, the rate of hospital admission for acute asthma is higher among Asians than among other groups in the population; betel-nut chewing may be one of several factors that affect asthma control and severity of attacks.

Weiss RF. Herbal Medicine. Beaconsfield, England: Beaconsfield Publishers Ltd., 1988.