Used primarily in the treatment of multidrug-resistant tuberculosis, especially when first-line drugs are ineffective. It acts as a second-line antimicrobial agent by interfering with bacterial cell wall synthesis, specifically inhibiting enzymes involved in peptidoglycan formation. Due to its potential neurotoxicity, it is typically reserved for complex cases and administered under strict medical supervision. Also investigated for use in neurological research due to its action on NMDA receptors in the brain, suggesting possible cognitive enhancement applications, though not approved for this use clinically.