The belladonna alkaloids, while toxic, are also very useful medically. Atropine, hyoscyamine, and scopolamine are just a few examples. All of the
these possess some degree of anticholinergic activity, and differ in terms of pharmacodynamics such as soluibility in fats and receptor specificity.
For example hyoscyamine is particulary active peripherally, making very useful for colic, or cramping pains from irritation and spasm of smooth muscle
within the stomach, intestine or urinary tract. Atropine has a strong cardiovascular effect, making it valuable in treatment of bradydysrrythmias
(dangerousl slowing of heart rate). Scopolamine has a particular affinity for the central nervous system, and it is responsible for a lot of the toxic
delirium seen with belladonna poisoning. These are veryi] potent - for example, the max dose of atropine used medically is only
2 mg, and as little as 0.2 mg has noticable effect. The dose for dangerous toxicity is not much higher. Toxic doses have a long half-life, so that if
you ingest Jimsom Weed or datura, you are going to be badly messed up for days.
It is said the the name belladonna derives from Italian and means "beautiful lady". Apparently the plant at one time was used by females for cosmetic
reasons. It was known that applying the plant juices to one's eyes would induce profound mydriasis (dilation of the pupils) that could last for days.
This was supposed to make a gal look prettier to the guys, even though she'd also probably be blind as bat! We use this effect medically as well to
dilate the pupils for opthalmoscopic examinations, and to relieve painful spasm of the iris muscle from eye disorders like uveitis.
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