I have read the post on here that explain how long it stays in your system the naltrexone that is.... I took one on saturday at 10am...then took sunday off no naltrexone...then monday took one at 1pm...now its wednesday 9:44 pm im good on not doing dope and stuff im an occasional user of H i just wanted to try the stuff out so ya of course i IV'd a bag to see if it really blocks it ((had to know)) and yes it did...i bought 2 anticipating the release of opiate accepting parts of my brain to enjoy this next one sooooo with that being said...tomorrow thursday at 1pm will be 72 hours im not looking to get ripped just dont want to waste the bag...should i wait until later in the day tomorrow, longer or what not... no rush on an answer anyone...this is my first post...NW-Indiana region friend - shplah