New film on the hunt for drugs to treat chronic pain - a detective story

Imperial researchers feature in a new film - 'The Pain Detective' - that explains the development of pain relief drugs through the eyes of a patient.

Pain is a double-edged sword, essential for protection against injury, but a cause of suffering when it becomes chronic. Current drugs provide limited relief for chronic pain, and developing new drugs has been a highly challenging task. The film, created by the Wellcome Trust, features retired policeman Colin Froy (aka the Pain Detective), telling the story of his pain and providing insight into how scientists are working to understand and treat pain.

Using his detective skills, Colin quizzes the professionals about aspects of drug development and clinical trials, and gets to see first-hand the work that goes on behind the scenes.

Colin participated in a clinical study at Imperial College London that involved application of a high-dose chilli patch, which alleviated his nerve pain for a month, and one of the opening scenes features Colin having a repeat patch application.

The patches contain capsaicin, the pungent ingredient of chilli peppers.  The hottest chilli in the world, known as the Caroline Reaper, scores more than 1.5 million on the Scoville Heat Unit scale. To put this in perspective, jalapeños fall into the 2,500-8,000 Scoville Unit range, while the Scotch Bonnet pepper spans 100,000–350,000 Scoville Units. Amazingly, the chemical version of capsaicin is 10 times hotter than the actual Caroline Reaper.

The film shows application of local anesthetic to Colin’s feet before applying the capsaicin eight per cent patch so he doesn’t feel the burning sensation. Professor Praveen Anand from Division of Brain Sciences, Imperial College London, explains the effect of capsaicin as “pruning the nerve endings” so the skin is no longer hypersensitive. 

The film also features footage of the use of human sensory neurons to enable the study of drugs and thereby reduce the reliance on animal models, which are known to be poor in predicting clinical efficacy.

Professor Anand’s group in the Neuropathy Unit has collaborated with the pharmaceutical industry, including  Pfizer Neusentis and MedImmune AstraZeneca who participated in the film, and also with Astellas who distribute the capsaicin eight per cent patch.

“There is an unmet need for patients suffering chronic nerve pain,” says Professor Anand. “By doing translational research linked closely with the pharmaceutical industry we have succeeded in developing drugs that have worked in recent clinical trials, and provided a model in this challenging area.”

‘The Pain Detective’ was produced as part of the Wellcome Trust’s digital publication Mosaic, which produces long-form features about the science of life. It is free for anybody to access and the content can be republished or shared.