Fletcher's Castoria is still being sold by Mentholatum (which was acquired by Rohto Pharmaceutical Co. Ltd of Osaka Japan in 1988) and they currently have a Fletcher's Castoria FAQ (
http://www.mentholatum.com/products.php?id=17), which discusses Castoria from a medical point of view. You can do a search on it here at Yahoo.com. The brief summary is that Fletcher's Castoria was patented in 1868, and has been in continuous manufacture since (as of July 2003). Unlike some of the other patent medicines of the day, Castoria's effectiveness was not merely hyperbole. Please read on if you wish to read more about it.
Centaur.com (http://www.centaur.com/) has a lot more information about it, and the company that manufactured it for many years (The Centaur Company) if you wish to look. More information will be appearing here as I (and others) have time.