UQ spinout to develop brain's own analgesic

In the New Age of "natural" remedies, there's no more natural a remedy for pain than the brain's native analgesic, endomorphin. It's an easy synthesis: a simple pentapeptide, that would be an instant winner for headaches and chronic neuropathic pain, if only someone could bottle it in tablet form.

The University of Queensland's commercial arm, Uniquest, is spinning off a new company to do just that. But Neurotide must solve some fundamental problems to develop an oral form of endomorphin.

Synthesised endormorphin quells both acute and chronic pain when injected directly into the brain, but its short half-life makes it unsuitable for treating the chronic, spontaneous pain of nerve injury, 'phantom limb' pain in amputees, and diabetic neuropathy.

And the two UQ researchers working on the project, professor Istvan Toth and Dr Joanne Blanchfield, must also solve the problem that bedevils all peptide and protein therapeutics: the oral route is barred because digestive enzymes break down peptides into their constituent amino acids.

Because endomorphin is the brain's own native painkiller, Toth said it was hoped it would not be addictive, unlike synthetic or plant-derived opiates like heroin and morphone, which target the same receptors on nerve cells in the brain.

There is currently no convenient, effective treatment for chronic neuropathic pain. Toth said conotoxins like Elan Pharmaceuticals' Ziconotide, derived from cone-shell venom, are effective in quelling chronic neuropathic pain, but can only be delivered intrathecally - by direct injection into the spinal cord - because they can cause blood pressure to rise dangerously.

Melbourne biotech Metabolic Pharmaceuticals (ASX:MBP) is working to commercialise a conotoxin developed by Melbourne University researchers that does not cause a blood-pressure rise when injected into the bloodstream.

Toth and Blanchfield hope to develop a stabilised endomorphin analogue that can be administered orally, and which will bind more strongly to endorphin and enkephalin receptors in the brain to provide sustained painkilling activity.

They are developing a more stable, lipophilic form of endorphin using polyethylene glycol (PEG), to protect the drug during transit through the digestive tract, and to enhance its penetration through the blood-brain barrier.

Neurotide recently received $249,450 funding from the Australian Government's Biotechnology Innovation Fund (BIF) to conduct proof-of-concept research.

Toth said Neurotide hopes to demonstrate within the next 18 months that the modified endomorphin can relive pain in vivo in animals, and will then proceed to human clinical trials.

The international market for painkilling drugs is estimated at US$38 million a year. Toth said the need was greatest in the neuropathic pain sector, which is estimated to be worth US$2.2 billion.