"Living with chronic pain, particularly for patients with terminal illnesses, is excruciating,” said Kelly M. Standifer, professor of pharmaceutical sciences at the OU College of Pharmacy.
While there are no exact numbers on how many Oklahomans cope with chronic pain, Standifer said many residents need some pain medication because of severe arthritis, back problems, migraine headaches, cancer, diabetes complications, accidents or injuries.
Many have fought chronic pain for more than a decade and some say their pain isn't under control, Standifer said of a recent health survey.
So an OU team used morphine as its primary research drug for improving pain control, but their findings could affect other related pain-relieving drugs such as methadone, fentanyl, hydromorphone, oxycodone and levorphanol, she said.
As Standifer noted, a person's tolerance for morphine and other drugs grows with continued use.
"For terminally ill patients and patients who live with chronic pain, opiates such as morphine often lose their effectiveness because that tolerance increases,” Standifer said.
"Increasing the dosage is not always an option because too much morphine can stop someone from breathing. Other side effects, such as constipation, can make the patient very uncomfortable and can make the pain worse,” she said.
Researchers discovered that a specific protein and the peptide nociceptin in the brain can affect morphine tolerance.
Chronic morphine use increases levels of nociceptin, researchers found.
However, she added, it was believed that blocking the actions of nociceptin reduces morphine tolerance — and helps with continued pain relief.
Why and how
OU researchers wanted to know why and how that happened.
They used brain cells and found that nociceptin activated a specific enzyme that made those brain cells less sensitive to morphine — suggesting why patients needed more morphine to get the same amount of pain relief over time.
Previous research had not shown that direct link.
"Our next step is to determine specifically where in the brain or spinal cord nociceptin is working to reduce morphine's effectiveness,” she said.
That's important for determining where other medications could be given to target drug therapy.
OU researchers now want to help find a way — most likely with new drugs — to reduce the development of morphine tolerance and help doctors more effectively treat patients with chronic pain.
"Our hope is to find alternatives to help doctors more effectively treat the pain and vastly improve the quality of life of patients,” she said.
Prev
