Definition: ACE-TA-MIDINE: A compound that contains a heterocyclic ring system and is structurally similar to aminoguanidine (AGN). It is used as an immunosuppressant in various medical conditions such as rheumatoid arthritis, lupus erythematosus, and multiple sclerosis. Acetamidine has been shown to exhibit antioxidant activity and may have potential therapeutic applications for diseases that involve oxidative stress.