Flexible packages, transdermal drug delivery devices, and methods for fabricating packages are provided. An exemplary flexible package includes a chemical and moisture resistant layer formed from poly(chlorotrifluoroethylene-co-vinylidene fluoride) (“P(CTFE-co-VDF)”) copolymer. Further, the exemplary flexible package includes a substance to be delivered. The substance is applied to or enclosed by the chemical and moisture resistant layer.