Abstract
Wounds are painful, particularly if they require debridement or suture. Systemic analgesics or injected local anaesthesia can be insufficient, unavailable and/or painful to administer. It would be ideal to have a topical anaesthetic product that could be promptly applied to any wound, regardless of its size or type, to immediately numb it, alleviate pain with prolonged effect, and provide sufficient anaesthesia to allow for debridement or suturing without the need for painful injected local anaesthetics. At present, however, aside from products used on minor cuts, there are few, if any topical anaesthetic products registered and approved (i.e., of proven safety and efficacy) for use on open wounds of this nature in humans. More-over, needed safety and efficacy data to support such applications are lacking. This is not the case in veterinary medicine however, where a combination topical anaesthetic and antiseptic solution formulated specifically for such use, has been developed, approved and is now extensively used for such indications. This is as a consequence of a 20-year research and development programme focused on developing a practical, yet safe and effective method of providing pain relief for livestock undergoing surgical husbandry procedures in Australia. These procedures, (such as castration, tail docking, dehorning and Mulesing), performed ‘in the field’ by farmers using a swift technique, leave painful open wounds that heal by secondary intention. Traditional pain relief methods were impractical, prompting us to explore topical anaesthesia. Trials led, in outcome, to the development of a formulation which combines rapid onset and long-acting local anaesthetics (lidocaine and bupivacaine), with a vasoconstrictor (adrenaline) and an antiseptic (cetrimide), in a viscous biocompatible base capable of being sprayed onto the wound and remining in place. Positive safety and efficacy data have supported multiple product registrations including to mitigate pain associated with castration wounds in sheep, cattle, and pigs; Mulesing and tail-docking wounds in lambs; scoop and cautery (burn) dehorning wounds in calves; infectious hoof and mouth ulcers in cattle. Six-7 million animals are now treated annually, with over 120 million animals treated to date. This editorial reviews data from this development programme, discusses new findings, and explores potential human applications.