The United States Pharmacopeia (USP) is a quasi-governmental organization that sets standards for the active and inert ingredients found in prescription and non-prescription drugs, veterinary drugs, and other health care products. If the lotions you refer to are considered "drugs" that require pre-market approval, it is possible that the moisture vapor transmission rate (MVTR) test found in USP Chapter 671 may be applicable. Packaging materials that are used with drug products must be approved by the U.S. Food and Drug Administration as part of a New Drug Application (NDA) or Abbreviated New Drug Applications (ANDA) before that product can be sold in the U.S. Since the USP is recognized in the Federal Food, Drug, and Cosmetic Act as an "official compendium," its standards for packaging materials may be legally enforced by FDA. A packaginglaw.com article on establishing regulatory compliance for drug and other types of nonfood packaging can be found here. If you would like assistance in determining the requirements for your specific product, please feel free to contact us.