University of Adelaide researchers have made a breakthrough in the treatment of heroin addiction which could improve treatment success rates for millions of heroin users around the world.

Researchers in the Discipline of Pharmacology have discovered a genetic variation that may help determine the most effective methadone dosage levels for individual heroin addicts.

The genetic discovery reveals why some people are either less efficient or more effective in distributing drugs throughout their body to the central nervous system.

Lead researcher Dr Janet Coller says accurate dosing of methadone is essential to successfully treat drug addicts because up to 62% fail to remain in the methadone program due to the severe withdrawal symptoms.

“Individualised dosing may decrease the incidence of withdrawal symptoms in some people and therefore encourage them to continue with the methadone treatment.”

An estimated 10 million people worldwide are heroin dependent, including 74,000 Australians, incurring enormous health, social and economic costs.

“More than 40,000 people are undergoing methadone treatment in Australia and only 38% of them are staying in the program at the moment. Most drop out at the start of the treatment when the withdrawal effects are severe,” Dr Coller says.

This breakthrough will allow individuals undergoing the methadone treatment program to be tested for the genetic variation to determine optimal treatment doses.

The pharmacology study was conducted collaboratively as part of Dr Coller’s postdoctoral and Daniel Barratt’s PhD studies, supervised by Professor Andrew Somogyi, with the assistance of Karianne Dahlen and Morten Loennechen, Masters of Science students from Denmark. The results have been published in the December issue of the journal Clinical Pharmacology and Therapeutics.