Flupirtine. A review of its pharmacological properties, and therapeutic efficacy in pain states.

Flupirtine is a novel non-opiate centrally acting analgesic agent with muscle relaxant properties, advocated for use in a number of pain states. Preliminary evidence suggests that flupirtine 100 to 200mg orally or 150mg rectally 3 to 4 times daily (maximum daily dose 600mg) is more effective than placebo in relieving moderate acute pain of various types. For the relief of pain due to surgery, traumatic injury, dental procedures, headache/migraine and abdominal spasms, flupirtine has proved at least as effective as the opiate analgesics codeine, dihydrocodeine and pentazocine, the nonsteroidal anti-inflammatory agents suprofen, diclofenac and ketoprofen, as well as dipyrone and paracetamol (acetaminophen). Although evidence to support a role in the treatment of chronic pain is limited, flupirtine has been found as effective as pentazocine in short term trials of patients with muscular or neuralgiform pain, dysmenorrhoea, soft tissue rheumatism or cancer pain. The safety profile of flupirtine has not yet been fully established, although initial evidence suggests that adverse reactions, while frequent, are usually minor in nature. The most common reactions are drowsiness, dizziness, dry mouth and various gastrointestinal complaints. In comparison with opiate drugs, flupirtine appears to produce fewer central nervous system effects, no respiratory or cardiovascular depression, and no overt tolerance or physical dependence on prolonged administration. If these initially favourable results are confirmed in larger long term trials, then flupirtine would appear to represent an effective analgesic for the relief of moderate pain, particularly that of musculoskeletal origin.