Hyoscyamine is a chemical compound, a tropane alkaloid it is the levo-isomer to atropine. It is a secondary metabolite of some plants.

GoldBamboo

... HYOSCYAMINE (Anaspaz®, Cystospaz®, Gastrosed®, Levbid®, Levsin®, Levsin/SL®, Levsinex®) treats different bowel problems including irritable bowel syndrome. Generic hyoscyamine extended-release capsules and tablets are available. ...
Drug Digest - more...

Hyoscyamine Systematic (IUPAC) name (8-methyl-8-azabicyclo[3.2.1] ...
Wikipedia - [full article]

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