Flupirtine Stats & Data
JUUFBMODXQKSTD-UHFFFAOYSA-NPharmacology
DrugBankDescription
Flupirtine is a pyridine derivative that is in clinical use as a nonopioid analgesic. It was approved for the treatment of pain in 1984 in Europe. It is not approved for use in the U.S. or Canada, but is currently in phase II trials for the treatment of fibromyalgia.
Mechanism of Action
Flupirtine upregulates Bcl-2, increases glutathione levels, activates an inwardly rectifying potassium channel, and delays loss of intermitochondrial membrane calcium retention capacity. Flupirtine acts like a NMDA receptor antagonists, but does not bind to the receptor. One study concluded that the discriminative effects of flupirtine are neither of opioid nor of alpha-1 adrenergic type, but are primarily mediated through alpha-2 adrenergic mechanisms PMID: 2901483.
Metabolism
Hepatic to 2-amino-3-acetylamino-6-(para-fluorobenzylamino) pyridine (which has 20-30% the analgesic potential of its parent compound) and Para-fluorohippuric acid.
Absorption
Bioavailability: 90% (oral), 70% (rectal)
Indication
Investigated for use/treatment in fibromyalgia.
Half-life
6.5 hrs (average), 11.2-16.8 hrs (average 14 hrs) (elderly), 8.7-10.9 hrs (average 9.8 hrs) (in those with moderate-level renal impairment).
Elimination
72% of flupirtine and its metabolites appear in urine and 18% appear in faeces.
Measured Affinities
Guide to PHARMACOLOGYMeasured binding and functional data for flupirtine, curated by the IUPHAR/BPS Guide to PHARMACOLOGY. Each row cites the paper it came from. Lower concentrations mean tighter binding — a value in the sub-nanomolar range indicates a very potent interaction.
| Target | Action | Measure | Value | Concentration | Species | Source |
|---|---|---|---|---|---|---|
| Kv7.2 KCNQ2 | Activator | pEC50 | 5 | 10,000 nM | Human | PMID 14736843 |
Reading this. pKi, pEC50 and pIC50 are negative log molar values, so a higher number means a tighter interaction; the concentration column converts them for you. Values from non-human species are laboratory measurements and do not translate directly to human effect. Receptor affinity is not a dose — it describes what a molecule binds, not how much of it is safe to take.
Receptor data from the IUPHAR/BPS Guide to PHARMACOLOGY (v2026.2), licensed CC BY-SA 4.0. Matched to this substance by InChIKey.
Toxicity
DrugBankToxicity (DrugBank)
Oral, mouse: LD50 = 300 mg/kg; Oral, rabbit: LD50 = 3200 mg/kg; Oral, rat: LD50 = 980 mg/kg.