D-Cycloserine is an NMDA receptor (NMDAR) partial agonist with antibiotic activity. It selectively binds to the glycine binding site (Ki = 2.33 μM) over the glutamate binding site (Ki = >100 μM).¹ D-Cycloserine modulates memory in a T-maze footshock test in CD-1 mice with optimal memory retention at doses of 10-30 mg/kg.² Administration of D-cycloserine (20-40 mg/kg) improves memory retention in ‘senescence-accelerated’ mice which exhibit impaired learning and memory. D-Cycloserine inhibits L-alanine racemase and D-alanine:D-alanine ligase, enzymes essential to peptidoglycan synthesis and bacterial cell wall formation.³ Formulations containing D-cycloserine have been used as second-line agents to treat drug resistant tuberculosis.⁴