Carbidopa/oxitriptan

Carbidopa / oxitriptan

Carbidopa (top) and oxitriptan (bottom)
Combination of
Carbidopa	Aromatic L-amino acid decarboxylase inhibitor
Oxitriptan	Serotonin precursor
Clinical data
Other names	Carbidopa/5-hydroxytryptophan; Carbidopa/L-5-hydroxytryptophan; Carbidopa/5-HTP; Carbidopa/L-5-HTP; EVX-101; EVX101
Routes of administration	Oral [1] [2]

Carbidopa/oxitriptan (developmental code name EVX-101), or carbidopa/5-hydroxytryptophan (carbidopa/5-HTP), is a combination of 5-hydroxytryptophan (5-HTP; oxitriptan), a serotonin precursor, and carbidopa, a peripherally selective aromatic L-amino acid decarboxylase (AAAD) inhibitor, which is under development as an add-on therapy for the treatment of obsessive–compulsive disorder (OCD) in people taking a selective serotonin reuptake inhibitor (SSRI). ^{[1] [3] [4] [2]} It is or was also under development as an antidepressant for the treatment of depressive disorders in people taking an SSRI or serotonin–norepinephrine reuptake inhibitor (SNRI) with an inadequate treatment response, but no recent development has been reported for this indication. ^{[1] [3] [5]}

The drug is taken orally. ^[1] It is a gastro-retentive sustained-release formulation of 5-HTP (250 mg per tablet) and low-dose carbidopa (0.3125–2.5 mg per tablet). ^[2] Use of 5-HTP alone is impractical due to poor pharmacokinetics and rapid metabolism. ^[2] Carbidopa enhances the pharmacokinetics of 5-HTP, for instance greatly increasing its oral bioavailability. ^[2] The elimination half-life of 5-HTP in combination with carbidopa was found to be 4.1 to 6.5 hours. ^[2] The purpose of carbidopa/oxitriptan add-on therapy is to further increase serotonin levels beyond that provided by an SSRI alone. ^[2] Circulating cortisol levels increased with the drug, which is a known biomarker for brain serotonin elevation. ^[2] Carbidopa/oxitriptan is analogous to carbidopa/levodopa, which contains carbidopa and the dopamine precursor levodopa (L-DOPA) and is approved and used to elevate brain dopamine levels to treat Parkinson's disease. ^[6]

Carbidopa/oxitriptan is under development by Evecxia. ^{[1] [3]} As of October 2025, it is in phase 1 clinical trials for OCD, with a phase 2 trial being planned. ^{[1] [3] [4] [7]}

See also

• List of investigational antidepressants
• List of investigational obsessive–compulsive disorder drugs
• Carbidopa/levodopa

References

1. "Carbidopa/oxytriptan - Evecxia". AdisInsight. Springer Nature Switzerland AG.
2. Carpenter D, McKenzie L, Beaudoin S, Totaro C, Zann V, Hart J, Klein R, Raskin J, Jacobsen J (June 2023). A Phase 1 SAD and MAD Trial of EVX-101, A Novel Gastro-Retentive Prolonged-Release 5-HTP/Low-Dose Carbidopa Tablet, in Healthy Subjects Taking Escitalopram (PDF). 2023 Annual Meeting of the American Society of Clinical Psychopharmacology (ASCP), Miami Beach, FL; May 30-June 2.
3. "Delving into the Latest Updates on EVX-101 with Synapse". Synapse. 8 May 2025. Retrieved 12 January 2026.
4. Chowdhry, Amit (23 September 2025). "Evecxia Therapeutics: $5 Million Secured To Advance OCD and Depression Treatments". Pulse 2.0. Retrieved 12 January 2026.
5. "Evecxia Therapeutics Reports Favorable Data From a Phase 1 Single-Ascending Dose and Multiple-Ascending Dose Trial of Adjunctive EVX-101 in Healthy Volunteers Treated With a First-Line Antidepressant". BioSpace. 10 April 2023. Retrieved 12 January 2026.
6. Müller T (May 2020). "Pharmacokinetics and pharmacodynamics of levodopa/carbidopa cotherapies for Parkinson's disease". Expert Opin Drug Metab Toxicol. 16 (5): 403–414. doi:10.1080/17425255.2020.1750596. PMID   32238065.
7. "Evecxia Provides Financing & Corporate Updates Including Plans for an EVX-101 Proof-of-Concept Phase 2 Clinical Study in Obsessive-Compulsive Disorder (OCD) Responding Inadequately to First-line Therapies". BioSpace. 23 September 2025. Retrieved 12 January 2026.

External links

• EVX-101 - Pipeline - Evecxia Therapeutics