Pharmacology
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)
Toxicity
Oral, mouse: LD50 = 300 mg/kg; Oral, rabbit: LD50 = 3200 mg/kg; Oral, rat: LD50 = 980 mg/kg.
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.