Malgaldrate is the actual chemical bonding and not just mixing of magnesium hydroxide and aluminum hydroxide. If taken with food, the protective effect may be 2 or 3 hours. To get as much acid reduction as prescription medicines produce is expensive as the antacid must be taken frequently during the day and night. It is probably cheaper to take an acid-reducing pill once or twice a day. All antacids, but especially calcium carbonate, can result in an acid rebound effect where the stomach acid surges back after the antacid has left the stomach, another reason for long-acting medications.
Antacids interfere with many drugs.
Staggering the antacid away from medications is always preferable but again is a nuisance and hard to comply with long-term. Antacids are useful for the temporary relief of occasional indigestion and heartburn. Frequent, daily or nightly symptoms usually mean a more serious problem. Antacids by themselves do not correct these problems. The medications that are now available to treat acid problems are generally superior to antacids.