Reformulated Imatinib Eliminates Morphine Tolerance in Lab Studies
By reformulating the common cancer drug imatinib (Gleevec®), researchers have eliminated morphine tolerance in rats – an important step toward improving the effectiveness of chronic pain management in patients, according to researchers at The University of Texas MD Anderson Cancer Center.
Narcotics such as morphine are a mainstay of chronic pain treatment. Over time, tolerance to the pain-relieving effects of these drugs can develop, requiring increasing doses to control pain. In some cases, narcotics become ineffective. This study, published online in Nature Medicine, is the first to identify a cellular signal that selectively causes narcotic tolerance.
“By suggesting a way to prevent or reverse tolerance in patients, this study could have far-reaching implications for many people suffering with chronic intractable pain,” said senior author Howard B. Gutstein, M.D., professor in the Departments of Anesthesiology/Perioperative Medicine and Biochemistry at MD Anderson.
One imatinib target causes morphine tolerance
In the study, scientists discovered that activating the - isoform of the platelet-derived growth factor receptor (PDGFR) caused morphine tolerance in animals not previously exposed to morphine.
Imatinib is commonly used to treat certain types of leukemia and gastrointestinal tumors. It targets a number of cellular receptors, including the PDGFR, which is heavily expressed in those cancer cells.
What is the important information I should know about GLEEVEC (Imatinib Mesylate)?
Take GLEEVEC (Imatinib Mesylate) exactly as directed by your doctor. If you do not understand these directions, ask your pharmacist, nurse, or doctor to explain them to you.
Take GLEEVEC (Imatinib Mesylate) only after the food intake to prevent the gastric irritation and perforations.
For GLEEVEC (Imatinib Mesylate) dosage one must follow his doctor’s instructions.
It is important to take GLEEVEC (Imatinib Mesylate) regularly to get the most benefit, as directed by the Physician.
You should maintain strict oral hygiene while you are taking GLEEVEC (Imatinib Mesylate).
Do not stop taking GLEEVEC (Imatinib Mesylate) without first talking to your doctor, even if you are feeling well. Even after your symptoms improve, you may require continuous treatment for quite some time, as directed by the Physician.
If you missed GLEEVEC (Imatinib Mesylate) for a long period of time, consult your Physician before restarting the medicine, as you may need low dose than earlier.
Store GLEEVEC (Imatinib Mesylate) as per the instructions on the label.
Keep GLEEVEC (Imatinib Mesylate) away from the reach of the children and pets.
In this study, imatinib prevented morphine tolerance, and importantly, completely reversed tolerance in rats that received high morphine doses continuously for several days, which reflects how morphine and other opioids are often given to chronic pain patients.
Researchers modify imatinib to block PDGFR
Morphine and other opioids work by binding to mu opioid receptorsin the brain and spinal cord.
Imatinib’s ability to inhibit morphine tolerance has not yet been observed in cancer patients who take imatinib because the drug does not penetrate the nervous system. Gutstein’s group reformulated imatinib using a simple, clinically approved carrier molecule called Captisol® that markedly increased drug delivery to the brain.
“What’s particularly exciting is that imatinib already is approved for use in humans, which suggests that we might be able to utilize this discovery to treat patients fairly soon,” Gutstein said. He emphasized that the reformulated imatinib must first be tested for efficacy and safety in further animal studies, then in humans in a Phase I study.
Potential to reduce debilitating side effects
“Many patients in severe pain often refuse high doses of opioids because of the side effects, and they desperately need relief,” Gutstein said. “We may be able to quickly translate this discovery and dramatically reduce the suffering endured by the sickest patients, and not just those with cancer.”
Patients taking morphine and other opioids can experience side effects ranging from unpleasant to life-threatening in their intensity, including itching, constipation, nausea and breathing depression. Reducing morphine tolerance could allow the use of lower doses to relieve pain with fewer side effects.
Additional scientists conducting the studies from MD Anderson’s Departments of Anesthesiology and Biochemistry and Molecular Biology include: Yan Wang, Ph.D., Katherine Barker, Ph.D., Shanping Shi, Miguel Diaz, and Bing Mo, Ph.D.
The study was funded by research grants from the U.S. National Institute on Drug Abuse and the U.S. National Institute on Alcohol Abuse and Alcoholism. The authors have no competing financial interests.
About MD Anderson
The University of Texas MD Anderson Cancer Center in Houston ranks as one of the world’s most respected centers focused on cancer patient care, research, education and prevention. MD Anderson is one of only 40 comprehensive cancer centers designated by the National Cancer Institute. For eight of the past 10 years, including 2011, MD Anderson has ranked No. 1 in cancer care in “America’s Best Hospitals,” a survey published annually U.S. News & World Report.
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Source: University of Texas M. D. Anderson Cancer Center