Molecule

Drug Groups

approved

Description

Nicotine is highly toxic alkaloid. It is the prototypical agonist at nicotinic cholinergic receptors where it dramatically stimulates neurons and ultimately blocks synaptic transmission. Nicotine is also important medically because of its presence in tobacco smoke. [PubChem]

Indication

For the relief of nicotine withdrawal symptoms and as an aid to smoking cessation.

Pharmacology

Nicotine, the primary alkaloid in tobacco products binds stereo-selectively to nicotinic-cholinergic receptors on autonomic ganglia, the adrenal medulla, neuromuscular junctions and in the brain. Nicotine exerts two effects, a stimulant effect exerted at the locus ceruleus and a reward effect in the limbic system. Itranvenous administration of nicotine causes release of acetylcholine, norepinephrine, dopamine, serotonine, vasopressin, beta-endorphin and ACTH. Nicotine is a highly addictive substance. Nicotine also induces peripheral vasoconstriction, tachycardia and elevated blood pressure. Nicotine inhalers and patches are used to treat smoking withdrawl syndrome. Nicotine is classified as a stimulant of autonomic ganglia.

Toxicity

Symptoms of overdose include nausea, abdominal pain, vomiting, diarrhea, diaphoresis, flushing, dizziness, disturbed hearing and vision, confusion, weakness, palpitations, altered respiration and hypotension. LD₅₀= 24 mg/kg (orally in mice).

Affected Organisms

Biotransformation

Primarily hepatic, cotinine is the primary metabolite.

Absorption

Absorption of nicotine through the buccal mucosa is relatively slow and the high and rapid rise followed by the decline in nicotine arterial plasma concentrations seen with cigarette smoking are not achieved with the inhaler. About 10% of absorbed nicotine is excreted unchanged in urine.

Half Life

Cotinine has a half life of 15-20 hours, while nicotine has a half life of 1-3 hours

Protein Binding

Less than 5%

Elimination

About 10% of the nicotine absorbed is excreted unchanged in the urine.

Distribution

* 2 to 3 L/kg

Clearance

* 1.2 L/min [healthy adult smoker]

References

External Links