First 'photo-drug' for pain can be activated with light

Researchers have designed the first "photo-drug" to treat pain that can be specifically activated with light at any moment.
Common pharmacology can limit the therapeutic action of any drug, said researchers, including those from University of Barcelona in Spain.
Using light on a photosensitive drug, the pharmacological process can be controlled with spatial and temporal precision, they said.
The drug JF-NP-26 has powerful therapeutic applications to treat pain and can be specifically activated at any moment with light.
"In the clinical field, there is not any precedent of the uses of optopharmacology to improve pain treatment or any disease associated with the nervous system. This is the first light-activated drug designed for the treatment of pain in vivo with animal models," said Francisco Ciruela, Professor at University of Barcelona.

In the new optopharmacology proposal published in the journal eLife, a drug with a known action mechanism (for example an analgesic) is chemically modified to make it photosensitive and inactive.

This drug is activated when receiving light - using an optical fibre - of a suitable wave length and with an exact precision on the target tissue (brain, skin, articulations, etc).
Compared to other photosensitive compounds, JF-NP-26 is a molecule that has no pharmacological effect on an animal until the target tissue received light from a visible spectrum (405 nm wave length).
Moreover, JF-NP-26 does not show toxic or unwanted effects even if the dose is high, researchers said.

The drug's lightening includes a treatment on the molecule that releases the active molecule (raseglurant) that blocks the metabotropic glutamate type 5 (mGlu5) receptor, found in lots of neuronal functions such as the spread of neuronal pain.
Blocking this receptor allows preventing the pain from spreading into the brain. This can be produced both due the outlying neurons and the central nervous system (brain) and create, in both cases, an analgesic effect as a result.
"The molecule created by the action of the light, the raseglurant, does not belong to any group of drugs from the classic anti-pain list of drugs: non-steroidal anti- inflammatory drugs or NSAID (paracetamol, ibuprofen, etc) and opioids (morphine, phentanyl).

"Consequently, the study describes an analgesic mechanism which has not been explored enough so far," said Ciruela.