Category: amino-acid
Aliases: Orn, L-Ornithine, L-Ornithine HCl
Non-proteinogenic basic AA produced from arginine by arginase (liver and kidney) — not incorporated into proteins because no codon exists. Central urea-cycle intermediate: condenses with carbamoyl phosphate via OTC to form citrulline. Also the substrate for ornithine decarboxylase (ODC) → putrescine → spermidine / spermine (polyamine pathway, rate-limited by ODC). Oral F limited by saturable cationic-AA transport (shared with arginine, lysine). Clinical LOLA formulation enhances hepatic urea synthesis and glutamine release, lowering plasma ammonia in cirrhosis.
PO: 1.2h, IV: 1.2h