Rabeprazole
Rabeprazole is a proton pump inhibitor: it shuts down the acid-producing pumps in the stomach lining, so much less acid is made until new pumps are built. Lower acid gives inflamed tissue a chance to heal. It is used for heartburn and for stomach and duodenal ulcers.
It is taken in the morning on an empty stomach, before the first meal of the day, because the pumps to be blocked are the ones switched on by eating. Because stomach acid is needed to free vitamin B12 from food and to absorb iron, long use can lower both, and magnesium can also drift down, which is why B12 and magnesium are worth checking on extended courses. The need for a long course should be reassessed rather than repeated indefinitely, and a doctor decides when it ends.
Persistent muscle cramps, twitching, palpitations, unusual tiredness, numbness or tingling, or heartburn that keeps coming back despite treatment are reasons to see a doctor rather than continue on one's own.
Reference information, not medical advice. Discuss any change with your doctor.