yes, I did use this mag64... it seems unstable in the bottle when exposed to moisture. But all mag will do this as it is hygroscopic.

If you mix it with other things in a pill dispenser, you might find it ruining other drugs/supplements. Once you open the bottle if you can add some dryness canisters (you can ask your pharmacist to save some for you), it might last longer. I didn't use every day, because I am very sensitive to the oral mag laxative action. Others here may be less sensitive. People on opiates or high dose Tramadol may favor the laxative actions. I much prefer the topical Morton's lotion + nuts and high mag containing foods. This way I don't get so upset.

Mag64 is a money saver depending on where you purchase it.
The best price I found is at Costco on special order! I used to get it for around 5 bucks a bottle there. SlowMag brand name is a good buy at WalMart, even if they order it for you especially.