P5P (Pyridoxal-5'-Phosphate) — Active B6

P5P is the active coenzyme form of vitamin B6 — bypasses hepatic conversion needed for pyridoxine (regular B6). Relevant for: people with impaired liver conversion, those on drugs that inhibit B6 activation (theophylline, isoniazid, oral contraceptives, penicillamine). 25-100mg/day. High-dose pyridoxine (>200mg/day) can cause PERIPHERAL NEUROPATHY — P5P may have lower neuropathy risk but data is limited. --- *Reviewed by the Dose AI Research Team and Clinical Advisory Board* *Last updated: 2026-04-06*