Alka-seltzer and Gastric antacid

Alka-seltzer noun - A commercial antacid that contains aspirin; tablets dissolve in water to give an effervescent solution.

Gastric antacid and Alka-seltzer are semantically related. In some cases you can use "Gastric antacid" instead a noun phrase "Alka-seltzer".

Gastric antacid noun - An agent that counteracts or neutralizes acidity (especially in the stomach).

Alka-seltzer and gastric antacid are semantically related. Sometimes you can replace phrase "Alka-seltzer" with "Gastric antacid", this phrases are similar.