Hi. I just wanted to share that TUMS actually work for Vyvanse too (not as much as Adderall). LDX is not going to be absorbed better if you take it at the same time but it works when the lisdexamfetamine is completely metabolized into dextroamphetamine. This is due to the increased pH in blood. The more basic pH will actually make the molecule more lyposoluble, so it will be excreted more slowly and also may cross the blood brain barrier again (from blood to the brain) due to the increased lypophilicity. I have to admit tho that calcium carbonate is known to produce a rebound effect, so after a few hours the blood pH will change from higher than usual to lower than usual, making the dextroamphetamine molecule more hydrophilic, so it will be excreted more quickly and it will cross the BBB but in the opposite way (from the brain to your blood)