Scientists can now block heroin, morphine addiction; clinical trials possible within 18 months

In a major breakthrough, an international team of scientists has proven that addiction to morphine and heroin can be blocked, while at the same time increasing pain relief.

The team from the University of Adelaide and University of Colorado has discovered the key mechanism in the body's immune system that amplifies addiction to opioid drugs. Laboratory studies have shown that the drug (+)-naloxone (pronounced: PLUS nal-OX-own) will selectively block the immune-addiction response. The results were published in the Journal of Neuroscience in August 2012.

The discovery overturns a long-held assumption. Opioid addiction was thought to work purely through the brain's reward pathways. But the researchers, led by Dr. Mark Hutchinson of Adelaide and Professor Linda Watkins of Colorado, showed that opioids also bind to an immune receptor called TLR4 (Toll-like receptor 4) — essentially tricking the immune system into treating the drug like a pathogen. The immune response amplifies the craving and the addiction.

(+)-naloxone blocks TLR4 without interfering with the opioid receptors that provide pain relief — meaning it could, in principle, separate the painkilling benefit of morphine from its addictive grip. In laboratory studies on rodents, the drug blocked the immune-driven addiction response while pain relief actually improved.

The researchers said clinical trials could be possible within about 18 months — though they cautioned that the leap from rodents to humans is long, and addiction in people involves far more than a single receptor.

If it works, the implications are enormous: safer painkillers for surgery and chronic pain, and potentially a new weapon against heroin addiction — one of the most destructive drug epidemics in the world.