Ornithine

Summary

L-Ornithine is a non-essential amino acid central to the urea cycle and nitrogen metabolism. Available primarily as a dietary supplement, it is used to support ammonia detoxification, promote growth hormone secretion, enhance exercise performance, and reduce fatigue. L-Ornithine L-Aspartate (LOLA) is used clinically in some countries for hepatic encephalopathy.

Mechanism of Action

Ornithine is a non-proteinogenic amino acid that serves as a key intermediate in the urea cycle, facilitating the conversion of ammonia to urea for excretion. It stimulates the release of growth hormone and insulin, serves as a precursor to polyamines (putrescine, spermidine, spermine) that regulate cell growth and differentiation, and is a precursor to proline and glutamate.

Routes of Administration

Goals & Uses

• Hepatic encephalopathy managementHepatologyModerate
• Wound healing and tissue repairSurgery / RecoveryLow
• Ammonia detoxificationMetabolic SupportModerate
• Growth hormone stimulationEndocrine / HormonalLow
• Exercise performance and fatigue reductionSports / PerformanceLow

Contraindications

• Known hypersensitivity to ornithine or formulation componentsAllergyHigh
• Severe renal impairmentOrganModerateKidney function concerns
• Pregnancy and lactationReproductiveModerate

Adverse Effects

• HeadacheNeurologicUncommonPain in the head or upper neck
• Gastrointestinal discomfortGastrointestinalCommon
• Nausea and vomitingGastrointestinalCommon
• Electrolyte imbalanceMetabolicUncommonAbnormal blood electrolyte levels

Drug Interactions

• RifaximinLow
• LactuloseLow
• Growth hormone / secretagoguesLow

Population Constraints

• Pediatric populationsAgeRelative
• Chronic kidney diseaseRenalRelative
• Patients with urea cycle disordersMetabolic DisorderRelative

Regulatory Status

• European UnionApprovedApproved: Hepatic encephalopathy (LOLA form)LOLA is approved in several EU member states for hepatic encephalopathy; regulatory status varies by country.
• United StatesUnapprovedAvailable OTC as a dietary supplement (DSHEA); not FDA-approved as a drug. LOLA not FDA-approved.
• United KingdomUnknownL-Ornithine available as a food supplement; LOLA prescription status varies; consult MHRA guidance.

L-Ornithine is sold as an over-the-counter dietary supplement in the US and many countries. L-Ornithine L-Aspartate (LOLA) is approved as a prescription drug in some European and Asian countries for hepatic encephalopathy but is not FDA-approved. Not classified as a peptide per se, but frequently grouped with amino acid therapeutics.

Evidence & Sources

No sources recorded yet.

Frequently Asked Questions