Metenkefalin
Also known as: [Met5]-enkephalin, MENK, Met-enkephalin, Methionine enkephalin, Tyr-Gly-Gly-Phe-Met
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Summary
Metenkefalin (Met-enkephalin) is an endogenous pentapeptide (Tyr-Gly-Gly-Phe-Met) belonging to the enkephalin family of opioid peptides. It is naturally produced in the adrenal medulla and distributed throughout the CNS. It has been investigated for immunomodulatory effects, particularly in HIV/AIDS and cancer, and for analgesic properties. It is not approved as a therapeutic agent in any major jurisdiction but has been explored in clinical trials.
Mechanism of Action
Agonist at delta-opioid receptors (DOR) and mu-opioid receptors (MOR); modulates pain signaling, immune function, and neuroendocrine activity by binding to opioid receptors in the central and peripheral nervous systems.
Routes of Administration
Goals & Uses
- Anti-tumor activityOncologyLow
- ImmunomodulationImmunologyLow
- Mood and stress modulationNeuropsychiatryLow
- AnalgesiaPain ManagementLow
Contraindications
- Known hypersensitivity to enkephalins or opioid peptidesAllergyHigh
- Concurrent use of opioid antagonistsDrug InteractionModerate
- Respiratory depression riskPulmonaryModerate
Adverse Effects
- Injection site reactionsLocalCommon
- HypotensionCardiovascularUncommonLow blood pressure
- NauseaGastrointestinalUncommonFeeling of sickness or urge to vomit
- SedationCNSUncommon
Drug Interactions
- Enkephalinase inhibitors (e.g., thiorphan)Moderate
- Naloxone / NaltrexoneHigh
- CNS depressants (benzodiazepines, barbiturates)Moderate
Population Constraints
- PregnancyReproductive SafetyRelative
- Pediatric populationsAgeRelative
- Severe hepatic or renal impairmentOrgan ImpairmentRelative
- Opioid use disorder historyPsychiatric/Substance UseRelative
Regulatory Status
- European UnionUnapprovedNot approved by EMA. No active marketing authorization applications on record.
- United StatesUnapprovedNot FDA-approved. Investigated under IND protocols in HIV/AIDS and oncology contexts in the 1980s–1990s. Currently a research compound.
- United KingdomUnapprovedNot approved by MHRA. Remains a research-only compound.
Not approved by FDA, EMA, or MHRA as a drug. Has been investigated in clinical settings (e.g., under the name Methionine enkephalin or TNX-355 context not applicable; studied under IND protocols). Marketed illicitly in some jurisdictions under names like 'Opiorphin' or 'MENK'; regulatory oversight is limited.
Evidence & Sources
No sources recorded yet.
Frequently Asked Questions
What is Metenkefalin?
Metenkefalin (Met-enkephalin) is an endogenous pentapeptide (Tyr-Gly-Gly-Phe-Met) belonging to the enkephalin family of opioid peptides. It is naturally produced in the adrenal medulla and distributed throughout the CNS. It has been investigated for immunomodulatory effects, particularly in HIV/AIDS and cancer, and for analgesic properties. It is not approved as a therapeutic agent in any major jurisdiction but has been explored in clinical trials.
What is Metenkefalin used for?
Metenkefalin is educationally associated with: Anti-tumor activity, Immunomodulation, Mood and stress modulation, Analgesia. Educational only — not medical advice.
How is Metenkefalin administered?
Recorded routes of administration: Intranasal, Intravenous, Oral, Subcutaneous.
What are the potential side effects of Metenkefalin?
Reported adverse effects include: Injection site reactions, Hypotension, Nausea, Sedation. This list is not exhaustive — consult a qualified clinician.
Who should avoid Metenkefalin?
Recorded contraindications: Known hypersensitivity to enkephalins or opioid peptides, Concurrent use of opioid antagonists, Respiratory depression risk. Consult a qualified clinician before use.