Nicotine gastrointestinal effects

Gastro/ntest/na/Tobacco has gastrointestinal effects that result from parasympathetic stimulation, with a net effect of increased bowel activity (Taylor 1996). Initial exposure to nicotine typically causes nausea, vomiting, and occasionally diarrhea. 

Nicotine - The effects of nicotine on functions of the gastrointestinal tract are of interest both pharmacologically and clinically. Single doses of nicotine depress basal secretion in rats,104 normal persons and... 

Additional effects of nicotine include an increase in gastric acid secretion and an increase in the tone and motility of the gastrointestinal tract. These effects are produced because of the predominance of cholinergic input to these effector systems. 

Galantamine, unlike the other anticholinesterases in clinical use, is derived from the alkaloids from the daffodil and snowdrop family. It is a reversible, competitive inhibitor of acetylcholinesterase with some inhibitory action on butyryl cholinesterase. It is also an agonist at nicotinic receptor sites. Although a clinically effective drug, galantamine frequently causes gastrointestinal side effects. 

Actions Carbachol has profound effects on both the cardiovascular system and the gastrointestinal system because of its ganglion-stimulating activity and may first stimulate and then depress these systems. It can cause release of epinephrine from the adrenal medulla by its nicotinic action. Locally instilled into the eye, it mimics the effects of acetylcholine, causing miosis. 

Two reviews (2,3) of the use of metrifonate in Alzheimer s disease have been published. Both reported a positive effect of metrifonate, with generally mild and usually transient adverse effects, consisting of gastrointestinal symptoms (such as abdominal pain, diarrhea, flatulence, and nausea, probably reflecting cholinergic overactivation) and leg cramps, possibly caused by the overstimulation of nicotinic receptors at the neuromuscular junction. No laboratory abnormalities were reported. 

Carbachol is a quaternary ammonium compound that shares both the muscarinic and nicotinic actions of acetylcholine but is much more slowly deactivated. Carbachol has been used topically in ophthalmology and systemically (subcutaneously, for example in doses of 2 mg/day) for urinary retention. Severe cholinergic effects can result. In one instance they primarily involved the gastrointestinal tract and the patient died of esophageal rupture (1). In other cases patients have experienced extreme bradycardia with hypotension, requiring treatment with intravenous atropine. As carbachol is not destroyed by cholinesterase, a cumulative effect is possible in patients who receive regular doses at short intervals in one case, hypotension only developed on the third treatment day (2). 

Toxic effects occur within seconds to 5 min of nerve agent vapor or aerosol inhalation. The muscarinic effects include ocular (miosis, conjunctival congestion, ciliary spasm), nasal discharge, respiratory (bronchoconstriction and increased bronchial secretion), gastrointestinal (anorexia, vomiting, abdominal cramps, and diarrhea), sweating, salivation, and cardiovascular (bradycardia and hypotension) effects. The nicotinic effects include muscular fa-sciculation and paralysis. CNS effects can include ataxia, confusion, loss of reflexes, slurred speech, coma, and paralysis. 

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