Lobelia

Scientific Name(s): Lobelia inflata L.
Common Name(s): Asthma weed, Bladderpod, Eyebright, Gagroot, Indian tobacco, Indian weed, Pukeweed, Vomitwort

Medically reviewed by Drugs.com. Last updated on Feb 20, 2024.

Clinical Overview

Use

L. inflata and its major alkaloid, lobeline, have been used in smoking cessation programs and proposed for treatment of other drug dependencies. The sale of over-the-counter (OTC) lobeline products for smoking cessation was prohibited by the US Food and Drug Administration (FDA) in 1993. Lobeline has traditionally been used to treat asthma and bronchitis. However, clinical trial data are lacking to recommend use for any indication.

Dosing

Clinical trials are lacking to support the use of lobelia or provide dosing recommendations. Traditional use of the leaf (ie, as an expectorant) suggests 100 mg of dry herb up to 3 times a day. Doses of 0.6 to 1 g of the leaf are considered toxic, while 4 g of the leaf is considered to be fatal.

Contraindications

Contraindications have not been clearly defined; however, the sale of lobelia OTC products for smoking cessation is prohibited by the FDA due to a lack of efficacy and safety evidence.

Pregnancy/Lactation

Avoid use. Evidence of safety is lacking. Adverse effects have been documented, including loss of uterine tone.

Interactions

None well documented.

Adverse Reactions

Lobelia and lobeline are capable of inducing nausea, vomiting, tremors, and dizziness at high doses. Lobelia alkaloids are cardioactive; cardiotoxicities (ie, hypotension, tachycardia, convulsion) have been reported.

Toxicology

Toxic dosages of the plant have been described: 1 g of leaf is toxic, while 4 g of leaf is considered a fatal dose.

Scientific Family

• Campanulaceae (bellflower)

Botany

L. inflata is a branching, perennial herb that is completely self-fertilizing and reproduces only once in its lifetime.Hughes 2014 It grows from 0.3 to 0.9 m in height and produces small, violet-pinkish flowers in the alternate leaf axils. The base of the flower expands to form the seed capsule, which is the source of the name "inflata." L. inflata is native to the eastern half of United States and parts of Canada.Khan 2010, USDA 2019 The genus Lobelia has more than 400 recognized species, some of which contain alkaloids similar to those of L. inflata, including Lobelia chinensis, a plant important in traditional Chinese medicine.Khan 2010

History

The lobelia plant was named in honor of Matthias de Lobel, a 16th century Flemish physician and botanist. American Indians smoked the leaves like tobacco and used them medicinally for respiratory ailments. Lobelia was introduced into New England medical practice in the 18th century for use in producing emesis. It was also used in treating colic, rheumatism, fever, and asthma. By the 19th century, lobelia was considered an important medicinal plant used in many conditions (eg, abscess, insomnia, tetanus, shock); however, fatalities were recorded due to dosing inconsistencies.Bolyard 1981, Felpin 2004 In 1993, the sale of lobelia OTC products for smoking cessation was prohibited by the FDA.Duke 2002, FDA 2019, Khan 2010

Chemistry

The piperidine alkaloid lobeline was isolated as the main active component of lobelia,Wieland 1921 and its absolute stereochemistry was later determined.Schöpf 1965 The main components identified in Lobelia species are alkaloids, in particular lobeline, as well as lobelanine, norlobelanine, lobelanidine, and radicamine, among others, as well as flavonoids such as apigenin, luteolin, and quercetin. Other compounds include terpenes, alkynes (eg, polyacetylenes such as lobetyolin and lobetyolinin), coumarins, and mineral elements.Chen 2014, Folquitto 2019, USDA 2014, Yang 2014 Lobeline concentration is highest in the seeds of the plant.Dwoskin 2002

Uses and Pharmacology

Lobelia has mostly been used in preparations aimed at reducing respiratory tract disorders and as a smoking deterrent. Lobeline has CNS and peripheral effects similar to nicotine; however, it is not as potent. It initially causes CNS stimulation followed by respiratory depression.

Lobeline has a high affinity for nicotinic acetylcholine receptors and exhibits both agonist and antagonistic actions.Damaj 1997, Dwoskin 2002, Flammia 1999, Kaniakova 2014, Lobelia 2017 Because of large diversity of the nicotinic receptor subtypes identified, lobeline's actions are thought to be only partly caused by agonism at nicotinic receptors, with some subtypes insensitive to lobeline.Briggs 1998, Decker 1995, Parker 1998 Similar to nicotine, stimulation of respiration and bronchoconstriction has been observed with lobelineKlide 1968; however, lobeline exhibits a slow rate of unbinding from receptorsKaniakova 2014 and might act via a different mechanism than does nicotine.Dwoskin 2002, Teng 1997 The effects of lobelin on N-methyl-D-aspartateRao 1997 and [3H]5-HTLendvai 1996 and norepinephrineSántha 2000 release have been described. A review of potential mechanisms of action has been published.Dwoskin 2002 Both preclinical and clinical data exist supporting nicotinic acetylcholine receptor–based ligands (eg, lobeline) as promising therapeutic agents for the treatment of alcohol and drug dependence.Rahman 2015

Addiction to psychostimulants

Animal data

Experimental work has provided evidence that lobeline may be useful in the treatment of amphetamine abuse, based on blockade of amphetamine-induced dopamine release in rat striatum, and the observed high affinity of lobeline for opioid receptors.Dwoskin 2002, Hart 2010 Lobeline attenuated the self-administration of amphetamine, methamphetamine, and heroin in various rat experiments.Harrod 2001, Hart 2010, Neugebauer 2007, Nickell 2014 In several rodent models, lobeline had a selective effect on amphetamine-induced behavior and neurochemistry.Miller 2001 Limitations of lobeline use include a need to determine its behavioral profile; self-administration of lobeline in a manner similar to cocaine and nicotine has been observed in drug-naive mice,Rasmussen 1998 although this finding has been disputed.Dwoskin 2002 In addition, cross-tolerance to nicotine has been observed.Flammia 1999

Addiction to tobacco

Animal data

Experiments in rodents and in vitro studies have produced equivocal results, possibly reflecting a diversity of experimental procedures, as well as the actions of lobeline on various receptor sites.Benwell 1998, Dwoskin 2002, Lecca 2000, Tani 1998

Clinical data

Lobeline was a component of OTC products for smoking cessation for many years. Results from clinical studies on the efficacy of lobeline have been mixed, Grabowski 1985, Plakun 1966, Schuster 1979 and a meta-review found that none of the available studies were adequately controlled or of sufficient duration to prove its efficacy.Glover 2010, Stead 2012 As part of its OTC review process in 1993, the FDA required the removal of lobeline products for smoking cessation from the market because of a lack of demonstrated efficacy.FDA 2019

Antimicrobial and antiviral activity

Animal and in vitro data

Using the disc diffusion method, methanolic and ethanolic extracts of inflorescence have demonstrated inhibition against respiratory tract pathogens (eg, Klebsiella pneumonia, Staphylococcus aureus).Folquitto 2019 Orally administered lobeline inhibited herpes simplex virus (HSV) type 1 replication in mice (ie, decreased HSV titer).Kuo 2008

Cancer

Animal and in vitro data

Lobeline and extracts of L. chinensis have been studied in vitro and in rodents for anticancer activity. In mice, an extract of L. chinensis inhibited the growth of liver and gastric cancersChen 2014 and reduced the number of precancerous colon lesions.Han 2013 In human cancer cell lines, lobeline showed potential to reverse P-glycoprotein–dependent multidrug resistance in tumor cells.Ma 2008

CNS effects

Animal data

Experiments have shown that lobeline exerts analgesic,Damaj 1998, Khan 2001 enhanced memory and learning,Levin 1996, Vicens 2000 antidepressant,Roni 2014 and anxiolytic effects.Dwoskin 2002, Felpin 2004, Martin 2018, Roni 2015 Lobeline has also been shown to reduce seizures in mice, possibly by increasing the levels of gamma-aminobutyric acid in the brain.Tamboli 2012 In addition, a study in adult male mice demonstrated that lobeline has anticonvulsant and neuroprotective actions that may be mediated by antioxidant-like mechanisms, indicating lobeline's potential as a candidate in alcoholism therapy.da Costa E Silva 2018

Clinical data

A small study in volunteers with attention-deficit/hyperactivity disorder (ADHD) (N=42, with only 9 subjects completing the study) evaluated the effects of lobeline on ADHD compared with placebo and methylphenidate. No discernable difference with lobeline was observed; however, the small study size could be responsible for the lack of effect.Martin 2018

Respiratory effects

Lobeline has traditionally been used for the management of respiratory conditions (eg, pneumonia, asthma, bronchitis) because it induces coughing and consequent expectorant action.Felpin 2004 With the development of more effective agents, lobelia use in respiratory conditions has become obsolete.

Clinical data

A group of researchers reported positive effects of lobeline on juxtapulmonary receptors using intravenous (IV) bolus administration.Anand 2009)

Dosing

Clinical trials are lacking to support the use of lobelia or provide dosing recommendations. The sale of OTC lobeline products for smoking cessation was prohibited by the FDA in 1993.FDA 2019

Lobeline (salt form undefined) doses of 7.5, 15, or 30 mg sublingually over a 7-day protocol were used in a study of patients with ADHD.Martin 2018

Traditional use of the leaf (ie, as an expectorant) suggests 100 mg of dry herb up to a maximum of 3 times a day.Duke 2002 Doses of 0.6 to 1 g of the leaf are considered toxic, while 4 g of the leaf is considered to be fatal.Duke 2002

Pregnancy / Lactation

Avoid use. Evidence of safety is lacking. Adverse effects have been documented, including loss of uterine tone.Duke 2002, Ernst 2002

Interactions

None well documented.

Adverse Reactions

Lobelia and lobeline are capable of inducing nausea, diarrhea, coughing, vomiting, tremors, and dizziness at high doses (lobeline sulfate 8 mg).Duke 2002 Respiratory effects have also been described; at high doses, lobeline can induce sensations of choking or breathlessness.Anand 2009, Butler 2001 The lobelia alkaloids are cardioactive; cardiotoxicities (ie, hypotension, tachycardia, convulsion) have been reported.Cohen 2010, Dangerous supplements 2010 Death from overdose has been recorded in historical literature; however, reports in the medical literature are lacking.Duke 2002, Khan 2010, Stead 2012 Irritant contact dermatitis due to occupational contact with the related Lobelia richardii was reported in a case report.Idriss 2012)

Toxicology

In cases of lobelia overdose, symptoms include diaphoresis, tachycardia, convulsions, hypothermia, hypotension, coma, and even death.Barnes 2007 Toxic doses of the plant have been described (0.6 to 1 g of the leaf is toxic, while 4 g of the leaf is considered to be fatal).Duke 2002 In studies in mice, the alkaloid lobeline was not genotoxic or mutagenic, and liver and kidney biochemistry appeared unaffected.da Costa E Silva 2014, Verde 2014

Index Terms

• L. inflata
• Livistona chinensis
• Lobelia chinensis

References

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