Ornithine
Ornithine, an amino acid. Non-proteinogenic basic AA produced from arginine by arginase (liver and kidney) — not incorporated into proteins… Oral half-life 1.2 h.
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.
PK: THE STORED ABSORPTION RATE WAS THE SOLVER DEFAULT WEARING A CITATION. A ka of 1.0/h is exactly what resolvePk substitutes when the field is ABSENT, and no source on this record states one. Removing it is NUMERICALLY A NO-OP — the resolver supplies the identical number — so no curve moves; what changes is that the record stops asserting an absorption rate it never measured. This is the same shape already found on a volume of 35 L, which is likewise the default at the seventy-kilogram reference. THE WIDER DEBT IS LEFT ALONE ON PURPOSE: twelve values account for 152 of the 276 authored absorption rates, but the other eleven are NOT the default, so deleting those would move their curves rather than leave them, which is the error this audit spent a batch documenting.
Pharmacokinetics
- Oral — t½ 1.2 h · F 10% · Vd 24.5 L
- IV — t½ 1.2 h · F 100% · Vd 24.5 L
Sources: PMID:19083482