Atropine

Atropine is a competitive antagonist of muscarinic cholinergic receptors. It is absorbed from the gastro-intestinal tract, and is excreted in the urine. It remains in the body for about 2-3 hours. Causes a decrease in bronchial and salivary secretions, increases the heart rate, and pupillary dilation. It is one of the chemicals, found in many of the nightshade species, that induces a "sensation".

-- Sometimes used in the treatment of snake bite or severe asthma attack