[Pharmacology of nicotine]

Nicotine has a small molecular weight and is absorbed via the mucosa (Guccal or nasal), the pulmonary alveoli and the skin. The phenomenon of autotitration explains how a dependent smoker can unconsciously change his method of smoking to maintain a steady nicotine level. Nicotine leads to a liberation of catecholamines by acting on the nervous system through the intermediary of nicotine receptors. There is increased vigilance and powers of intellectual concentration, an awakening reaction and some anxiolytic and euphoriant effects. From the cardiac stand point there is an increased heart rate and blood pressure, as a result of the sympathomimetic effects. Elimination is via the kidneys as unchanged nicotine, cotinine and 1'-N-oxide of nicotine. Nicotine has an addictive action and is capable of inducing pharmacological dependency, tolerance and withdrawal syndrome in cases of abrupt cessation. A knowledge of the pharmacology of nicotine is important in the process of stopping smoking.