Great question 🌿. Pyridoxine (vitamin B6) is not usually thought of as a psychiatric drug, but it does have several important uses in psychiatry and neuropsychiatry.
1.
Prevention and treatment of medication-induced side effects
- Isoniazid-induced neurotoxicity:
- Isoniazid (an anti-TB drug, sometimes used in psych patients with comorbid TB) depletes B6 → can cause neuropathy, seizures, and psychiatric symptoms.
- Pyridoxine supplementation prevents this.
- Hydralazine, penicillamine, cycloserine, levodopa (without carbidopa):
- These drugs interfere with B6 metabolism and may cause irritability, cognitive changes, or neuropathy.
- Antipsychotic-induced tardive dyskinesia:
- Some studies suggest high-dose pyridoxine (up to 1200 mg/day) may reduce tardive dyskinesia severity, possibly via GABA synthesis and antioxidant effect. Evidence is mixed, but it is used experimentally in resistant cases.
2.
Seizures and encephalopathy related to B6 deficiency
- B6 is a cofactor for glutamate decarboxylase, which converts glutamate → GABA.
- Severe deficiency → seizures, irritability, agitation.
- In infants, rare pyridoxine-dependent epilepsy presents with seizures and behavioral disturbance.
3.
Mood and anxiety disorders (adjunctive use)
- B6 is a cofactor in the synthesis of serotonin, dopamine, norepinephrine, and GABA.
- Deficiency can manifest with irritability, depression, confusion.
- Some small studies suggest supplementation (often combined with other B-vitamins) may help mild depression, premenstrual syndrome (PMS), or anxiety.
4.
Special clinical notes
- Alcohol use disorder: Chronic alcoholics often have multiple B-vitamin deficiencies. B6 deficiency can contribute to neuropathy, mood instability, and seizures.
- High homocysteine states (with B12/folate): B6 helps lower homocysteine, which has been linked to depression and cognitive decline.
✅ Summary:
In psychiatry, pyridoxine is mainly used to:
- Prevent neurotoxicity from drugs like isoniazid.
- Treat tardive dyskinesia (experimental, high dose).
- Correct deficiency-related mood/behavioral symptoms.
- Support neurotransmitter synthesis (serotonin, dopamine, GABA).
- Address comorbid states like alcohol dependence or homocysteine elevation.
Would you like me to prepare a compact clinical table (Indication → Mechanism → Typical dose) so you have a quick psychiatric reference for pyridoxine?
