Not sure but i doubt it, the mdma will dissolve in your stomach contents and absord into your system. Your meds stop acid production not stomach absorption. Acid reflux usally means your body produces so much acid causing you to reflux it into ur asophogus (AR also comes in forms of bad breath and burping but i assume u have too much acid as your symptom) you should be ok to go.
When I was on Nexium, I would just skip taking it that night and resume the next day. I'd be ok heartburn wise for a day without taking Nexium. Thank God I'm no longer a slave to heartburn.