Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Informational only. Not medical advice.INFORMATIONAL PLATFORM ONLY — NOT MEDICAL ADVICE, DIAGNOSIS, OR TREATMENT
Head-to-head comparison of L-Tetrahydropalmatine (L-THP) and Phenibut — mechanism, dosing, side effects, legal status, and pricing.
L-Tetrahydropalmatine (L-THP) is a non-peptide isoquinoline alkaloid naturally occurring in Corydalis yanhusuo and Stephania rotunda. It acts as a mixed dopamine receptor antagonist with affinity for D1, D2, D3, serotonin 5-HT1A, and alpha-1 adrenergic receptors, and facilitates GABA-A receptor binding. One randomized controlled trial in schizophrenia found no efficacy on psychiatric symptoms and unexpectedly raised inflammatory markers. Widely sold by gray-market vendors as a research chemical labeled “not for human consumption.”
Phenibut (β-phenyl-GABA) is a non-peptide small-molecule GABA analogue that acts primarily as a GABA-B receptor agonist, with weaker GABA-A activity and secondary binding to the α2-δ subunit of voltage-dependent calcium channels. Developed and approved in Russia/former Soviet states since the 1960s for anxiety, sleep disturbance, and related conditions, it is not FDA-approved and is not a lawful dietary ingredient in the United States; FDA has issued warning letters to supplement marketers. Phenibut is widely documented in case literature for dependence, severe withdrawal syndromes (including delirium and seizures), and is sold in a gray market as an unregulated nootropic despite regulatory action.
L-Tetrahydropalmatine (L-THP)
Phenibut
Category
Legal Status
Mechanism
Dose Range
Route
COA-verified vendors · trust score ≥70 required · single-vial price — bulk/bundle deals may be lower
L-Tetrahydropalmatine (L-THP)
No pricing data yet.
Check L-Tetrahydropalmatine (L-THP) prices →Phenibut
No pricing data yet.
Check Phenibut prices →COA corpus from Disclosed Labs — independently tested batches only.
L-Tetrahydropalmatine (L-THP)
2
COAs
99.1%
Avg purity
2
Labs
Phenibut
6
COAs
99.9%
Avg purity
4
Labs
One completed randomized, double-blind, placebo-controlled trial (NCT02118610; 63 adults with schizophrenia, 60 mg/day L-THP vs placebo for 4 weeks) found no significant benefit on positive, negative, depressive, or global symptom measures. The trial did show reduced extrapyramidal symptoms (p<.001, possibly confounded by anticholinergic co-medication) but unexpectedly raised inflammatory markers (sICAM-1 p=.004, CRP p=.039) rather than lowering them as animal data had suggested. Preclinical studies in rats demonstrated dose-dependent reductions in methamphetamine self-administration and reinstatement (1.25–5.0 mg/kg IP), reduced cocaine self-administration breaking points and discrimination (1.875–7.5 mg/kg), and decreased voluntary ethanol drinking in mice (10 mg/kg) via D2-receptor-mediated PKA signaling in dorsal striatum, without affecting locomotor activity at lower doses.
Key references
No registered interventional clinical trials were found on ClinicalTrials.gov (API totalCount=0). Phenibut was developed and used clinically in Russia beginning in the 1960s for anxiety, sleep disturbance, peri-operative sedation, asthenia, PTSD, stuttering, and vestibular disorders, reflecting legacy regulatory approval abroad rather than FDA-reviewed randomized controlled trial data. Human data otherwise consists of case reports and case series documenting toxicity, dependence, and withdrawal rather than controlled efficacy trials. Rodent studies showed decreased neuronal activation in hippocampus and neocortex, increased neuronal synchronization, and reduced behavioral reactivity/anxiety; rat brain membrane binding studies confirmed R-phenibut binding to the α2-δ subunit of voltage-dependent calcium channels and gabapentin-like anti-nociceptive effects in rodent pain models.
L-Tetrahydropalmatine (L-THP) and Phenibut are both in the Cognitive category and may have overlapping mechanisms. Researchers should review both profiles carefully, understand the mechanisms of action, and monitor the relevant biomarkers when combining compounds in the same class. As always, consult a licensed healthcare provider before making any decisions about combining research compounds.
This platform provides informational tools only, not medical advice. This comparison is for educational purposes only. Consult a licensed provider.
Frequency
Dosing Notes
Side Effects
Contraindications
Lab Testing
Disclosed Labs