Hi,
We use mineral oil in a tablet press in a pharmaceutical plant. Does anyone know what type of conditions and time is required to cause peroxide formation in the oil? Peroxides that contact the drug can then degrade it.

If you have an anti-oxidant additive in the oil, then there will not be any peroxides. BHT is commonly used to prevent oxidation, and should be listed in the USP or any other formulary.

I agree with Refrig - sounds like you may not be utlizing a USP product and may want to change to one that is clearly identified as such - or perhaps going to a simple 3H release agent spray rather than using a mineral oil might help as the 3H formulation would prohibit peroxyl forming additives from being included in the make up of the product out of shear formulation necessity. I have examples of both if you would like information on the products - email me and I will see if I can help further.

Time, temperature and oxygen promote hydroperoxide - thin films left on press/die are more prone to oxidation than bulk, oxidation rate doubles every 10C
Just as a side note. I worked with a stamping machine in a automotive plant having trouble with sludge in summer time. Turns out stamping oil - mineral oil based - had hydroperoxide building in summer. Addition of 100 ppm BHT did not help, determined original mineral oil had hydroperoxides so addition of BHT was after the fact. Although BHT stabilizes oil against oxidation, it produces hydroperoxide as by-product of its reaction with oxygen or peroxy radicals. What level of hydroperoxides are you measuring? Is there any antioxidants in your oil? Also did work with peanut oils in making potato chips - Vitamin E in oil in chip was neccessary to keep chips fresh during storage. Again during summer - Vitamin E (tocopherols) were depleting during shipment from South and hydroperoxides were starting to build greatly shortening shelf-life. Potato goes in 30% water chip comes out 30% oil - reason they never have to change oil.