What are the pharmacokinetics of S-adenosylmethionine?

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    Last Updated: April 23, 2025

    S-Adenosylmethionine has a half-life of approximately 80 to 100 minutes when administered intravenously and shows 80% to 90% bioavailability with intramuscular injection, whereas oral bioavailability is significantly lower at 2% to 3%. Enteric-coated capsules and novel formulations like phytate salts and solid lipid nanoparticles have been shown to improve oral bioavailability, although the latter have yet to be tested in humans.

    In humans, intravenous administration of S-adenosylmethionine (100 mg, 500 mg, and 0.5 mg/kg of body weight) directly into the bloodstream has a half-life of approximately 80 to 100 minutes.[1][2] Furthermore, there are detectable increases in S-adenosylmethionine concentrations in the blood and the cerebrospinal fluid after oral, intravenous, and intramuscular administration, suggesting that S-adenosylmethionine crosses the blood-brain barrier.[3]

    In humans, intramuscular administration of S-adenosylmethionine (0.5 mg/kg of body weight) shows approximately 80–90% bioavailability — i.e., 80–90% of S-adenosylmethionine injected into a muscle appears in the blood.[1] However, when orally administered in humans, the bioavailability of S-adenosylmethionine is poorer,[3][4] as low as 2–3% in some studies.[5] However, some studies show that enteric-coated capsules of S-adenosylmethionine, which are protected from degradation by stomach acid, have improved bioavailability in humans when compared to uncoated S-adenosylmethionine.[6][7] Novel formulations such as phytate salts[8] and solid lipid nanoparticles[9] have further improved oral bioavailability in rodents, but these formulations remain to be tested in humans.

    What are the pharmacokinetics of S-adenosylmethionine? - Examine