Research improves pain control for cancer sufferers

Research being carried out by the University of Queensland's School of Pharmacy in collaboration with the Multidisciplinary Pain Centre at Royal Brisbane Hospital has resulted in major improvements in the treatment of chronically ill cancer sufferers.

According to Associate Professor Maree Smith, although about 90 percent of cancer patients already get good pain relief with morphine, some types of cancer pain, such as that with head and neck cancer, require such large doses of morphine for pain control that patients can experience hypersensitivity. The touch of a sheet or the brush of caring relative's hand causes a painful condition called allodynia.

"Our research has shown that the hypersensitivity is a side effect of administering very large doses of morphine because more than half of each morphine dose undergoes a metabolic change in the liver to a new form called morphine-3-glucuronide," she said.

In the usual doses of morphine, which 90 percent of patients receive, the build-up of morphone-3-glucoronide in the body is not enough to produce this hypersensitivity side effect.

However, in the other 10 percent of sufferers, the build-up of this altered form of morphine can prevent patients from obtaining optimal pain relief.

A recent collaborative study involving Associate Professor Smith and Professor Tess Cramond of the Multidiscipline Pain Centre at the Royal Brisbane Hospital has treated patients experiencing this morphine-related hypersensitivity side effect by administering very low doses of the drug directly into the brain fluid.

The study had been completed and the results showed that patients experienced excellent pain relief with minimal side effects and that morphine given directly into the brain fluid is not metabolized to morphine-3-glucoronide, as it is in the liver.

The work has recently been published in an international journal called Anesthesia Analgesia.

"Our research is now focused on defining the brain mechanism through which morphine-3-glucoronide produces this hypersensitivity side effect. "Once we know this mechanism, it may be possible in the future to further improve the treatment of cancer pain."

The University of Queensland was named Australian University of the Year in 1998 and is a recognised leader in medical and health-related research and teaching.

Further information: Maree Smith, telephone 3365 2554