NEW DRUGS THAT COULD BE THE ANSWER

THOUSANDS of years after humans discovered the pain- relieving effects of opium, clinicians still rely on opioids to treat severe pain.

‘Opioids work best for people with serious injury or disease, such as cancer,’ explains Steve Bazire, an honorary professor at the school of pharmacy, University of East Anglia.

But the drugs are addictive and have side-effects, including constipation and drowsiness, says Dr Roger Knaggs, an expert in pain management at Nottingham University Hospitals NHS Trust.

There are new drugs coming on to the market, such as a type of opioid, buprenorphine; already licensed in the U.S., it is less addictive because its effects taper off at higher doses.

There are also new classes of pain drugs on the horizon. Resiniferatoxin (RTX) is a compound derived from a cactus-like plant, euphorbia

resinifera. The active ingredient binds to a receptor on nerve cells that senses pain.

Scientists are also looking at redeploying drugs licensed for other conditions. For instance, naltrexone, currently used to treat drug and alcohol addiction, is being trialled at a lower dose for pain, according to Dr Mike Platt, a consultant in pain medicine at Imperial College Healthcare NHS Trust, London.

The drug bars the action of microglial cells in the nervous system, which produce a protein causing pain to linger after an injury has healed.

Scientists are also trying to replicate the painkilling power of chilli. Chilli-based creams can deactivate receptors on nerve cells and stop pain, but don’t work for all. ‘So scientists are now looking for other compounds that could attach to these receptors,’ says Dr Platt.