Researchers create opioid that only activates at pain sites

Opioids are a highly effective and widely prescribed treatment for pain, but their widespread non-targeted activation of opioid receptors can result in many adverse side effects.

In a paper published in Science^[1]
(online, 3 March 2017), researchers engineered an opioid-receptor agonist that only activates peripheral opioid receptors under acidic conditions, as occurs with inflammation at injured sites.

Trialling the molecule in rats, they found it demonstrated a similar level of pain relief to fentanyl, without any of the typical side effects commonly observed from opioids, such as respiratory depression, sedation, constipation and addiction.

The researchers say that designing drugs to activate under specific pathological conditions could be a valuable strategy for future drug development.