The purpose of this study is to compare the blood drug levels of two prescribed medications, immediate-release omeprazole 40 mg powder and delayed-release omeprazole 40 mg capsule to determine which drug is better absorbed in patients with a slow stomach emptying (gastroparesis). Delayed-release omeprazole has a protective coating to prevent the drug omeprazole from being neutralized by stomach acid. Immediate-release omeprazole has sodium bicarbonate (antacid) which neutralizes the stomach acid, eliminating the need for a protective coating. Immediate-release omeprazole suspension may have a more rapid pharmacokinetic profile and greater overall drug absorption in gastroparesis.