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methionine

V03AB26

Forms & Strengths

Oral tablets 500 mg and 1 g
Oral solution 200 mg/5 mL
Powder for reconstitution (100 g)
Parenteral solution for PN (10 % w/v)

Adult Dosing

Hyperhomocysteinemia: 500–1000 mg PO daily
Cystathionine β‑synthase deficiency: 25–100 mg/kg/day divided BID/TID
Hepatic steatosis: 500 mg PO TID
Parenteral nutrition: up to 1 g/kg/day as part of AA mixture

Pediatric Dosing

Homocystinuria (CBS deficiency): 50–100 mg/kg/day divided doses
Hyperhomocysteinemia: 10–30 mg/kg/day PO divided
PN in infants: 0.5–1 g/kg/day as part of AA solution

Indications

Dietary supplement for protein‑malnutrition
Treatment of homocystinuria (CBS deficiency)
Adjunct in parenteral nutrition
Management of hyperhomocysteinemia to reduce cardiovascular risk
Support of hepatic lipid metabolism in fatty liver disease

Mechanism of Action

Essential sulfur‑containing amino acid; donor of methyl groups via S‑adenosyl‑methionine (SAM)
Precursor for cysteine and glutathione synthesis, enhancing antioxidant capacity
Facilitates remethylation of homocysteine to methionine through methionine synthase (B12‑dependent)
Improves hepatic VLDL export by supporting phosphatidylcholine synthesis

Contraindications

Known hypersensitivity to methionine or formulation excipients
Severe hypermethioninemia
Acute hepatic failure with impaired sulfur‑amino‑acid metabolism
Severe renal impairment (risk of accumulation)

Adverse Reactions

Nausea, vomiting, abdominal pain, diarrhea
Transient fishy or sulfur odor in breath/urine
Elevated plasma methionine levels (hypermethioninemia)
Rare allergic rash or urticaria

Drug Interactions

Vitamin B12, folate, and pyridoxine augment homocysteine‑lowering effect
High‑dose methionine may reduce efficacy of antiepileptic drugs that deplete folate (e.g., carbamazepine)
Concurrent levodopa may experience altered methylation metabolism
Excessive methionine can antagonize the antioxidant effect of N‑acetylcysteine

Curated Content: Needs Vetting Before Put to Clinical Use