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Amino acid (serotonin precursor)

Tryptophan

Brand names: Optimax

Tryptophan is an amino acid precursor of serotonin used as an adjunctive treatment in resistant depression, typically under specialist supervision.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

Clinical monograph

How it works

As a precursor in serotonin biosynthesis, it is thought to enhance central serotonergic activity, supplementing the action of conventional antidepressants.

Prescribing in practice

  • It has been associated with eosinophilia-myalgia syndrome, so it is restricted to specialist use with monitoring and patient registration in line with the SPC.
  • Combined with other serotonergic agents it increases the risk of serotonin syndrome.
  • Treatment should be reviewed for benefit, and patients monitored for eosinophilia and myalgic symptoms.

Monitoring

Monitor for eosinophilia-myalgia symptoms, including muscle pain and eosinophil count, and for features of serotonin excess.

Counselling the patient

  • Report any unexplained muscle pain, weakness or swelling promptly.
  • This medicine is used alongside other antidepressants under specialist guidance.
  • Tell your doctor about all other medicines you take, especially other antidepressants.

Evidence & guidelines

The association of tryptophan with eosinophilia-myalgia syndrome underlies its restricted specialist use, as reflected in MHRA and SPC guidance.

Reference: SmPC; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

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