I would call it an information sheet, but there is also a proper name for it that I can't remember. I think it is something like prospectus but that's not it.

Leaflet?

I found this on some legal documents for the EU. "The inclusion in the packaging of all medicinal products of a package leaflet is obligatory unless all information required is directly conveyed on the labelling." So in the eu it is called a package leaflet. http://ec.europa.eu/health/files/eudralex/vol-2/c/bluebox_06_2013_en.pdf

It wouldn't be a "prospectus", which is a legal document (e.g. a stock offering). The actual physical form is that of a "pamphlet", although I suppose that the average person would call it "the instructions". Since the drug instruction pamphlets in the USA are almost useless to the average person (who can understand structural chemical formulas?), we don't even talk about them! We focus more on the label on the drug bottle and instructions on the box. Perhaps others have ideas on the terminology.