my latest patch 1.72beta8 or 9 it is? has this softcoded, however it works only when using NWN©X, the script is 70_s3_healkit
Plus there is a small downside of my method, since NWScript has no way to determine poison/disease ID (without another NWNX plugin) it assigns random DC, but if you want to remove that part of the functionality its not a problem.