Would do it for longer than 4 weeks definately. Proper liver support, and you should be able to do 6-8. Use milk thistle, liv 52, and other supps, the more the merrier. Drink plenty of water, and have good fresh foods, no drinking whatsoever and you should be ok.
Since you won't be having any long acting injectables, I'd make sure to split into the most doses you can, so if you're going with 40 try 6-8 tabs a day split as many times before you go to bed.