2 The technology

2.1 Botulinum toxin type A (Botox, Allergan) is a purified neurotoxin complex, which is derived from the bacterium Clostridium botulinum. It has neuromuscular transmitter blocking effects. It has a UK marketing authorisation 'for the prophylaxis of headaches in adults with chronic migraine (headaches on at least 15 days per month of which at least 8 days are with migraine)'. The recommended reconstituted dose is 155–195 units, administered intramuscularly as 0.1 ml (5 units) injections to between 31 and 39 sites around the head and back of the neck. The recommended re-treatment schedule is every 12 weeks (see the summary of product characteristics).

2.2 The summary of product characteristics lists the following common adverse reactions that may be associated with botulinum toxin type A treatment: headache, migraine, facial paresis, eyelid ptosis, pruritus, rash, neck pain, myalgia, musculoskeletal pain, musculoskeletal stiffness, muscle spasms, muscle tightness, muscular weakness, and injection site pain. It states that 'in general, adverse reactions occur within the first few days following injection and while generally transient, may have a duration of several months or, in rare cases, longer'. For full details of adverse reactions and contraindications, see the summary of product characteristics.

2.3 The net price of a 200 unit vial is £276.40 (excluding VAT; 'British national formulary' [BNF] edition 63). The manufacturer estimates that the administration cost is £73 per treatment, based on a total treatment time of less than 30 minutes. The total cost for treatment and administration of treatment per 12 week cycle, assuming no vial sharing, is therefore expected by the manufacturer to be £349.40. Costs may vary in different settings because of negotiated procurement discounts.