We had to push extremely hard to get any medication at all for Avery. The last straw, I took my husband in to the pedi with me, fed Avery 10 minutrs before we saw the doctor, and let him watch her scream and vommit. Zantac did nothing for her, so we ended up on TWO other RX's. One was prevacid, and was amazing, and the other was Reglan (metaclopramide) which helped keep the reflux down. There was a huge decrease in her refluxing and screaming. The reglan does have side effects, so we were very careful about that one, and watching for signs of problmes. The prevacid can take several weeks to work, but we found it helpful even after a few days.
Avery did end up on a prescription formula due to dairy and soy protein intolerance, which contributed to her reflux. You might call the NICU and ask for a recipe for increasing calories using a different formula. That's what we did.