Researchers at the Johns Hopkins Oncology Center have developed the first under-the-skin narcotic drug implant for the treatment of pain in cancer patients. The researchers believe that the polymer implant could offer an alternative to external drug delivery systems used to treat serious pain and may be a potential technique for the management of drug addiction.
The button-sized polymer works much like the continuous-release birth control implant. It will be inserted under the skin through a tiny incision made under mild, local anesthetic. The polymer contains a highly concentrated powder form of the commonly used narcotic drug hydromorphone. The drug is released in a steady amount into the bloodstream over one to three months.
The shape and size of the polymer, which is made at Hopkins, controls the release of pain medication. "Different polymers will be available to meet the needs of a particular patient, so that patients requiring more pain control can get polymers that release more drug, and those with very stable requirements for pain medications can get one that lasts longer," says Stuart Grossman, M.D., associate professor of oncology and director of the Center's cancer pain program.
Results of safety tests of the polymer in animals are reported in the July 1996, issue of Pain, and human trials should begin within a year, he said.
Grossman and his team began developing the pain polymer five years ago as an inexpensive, abuse-resistant way of offering pain management to people in developing nations, where cancer rates are high, but little or no treatment for pain is available.
"India produces 80 percent of the world's opiates, yet only a minuscule amount of oral morphine was prescribed to cancer patients last year," says Grossman. "Because of limited financial resources as well as widespread concern about uncontrolled use of narcotics, governments in developing countries historically have limited the availability of narcotics for the management of pain." Grossman says physicians in India seem eager to offer patients the polymer, which can be easily implanted before patients return to their villages. Villagers, many of whom cannot read or write and do not own clocks, will not need to store medicines or remember when and how to take them. The new drug delivery system is also appealing to Indian physicians because it reduces concerns about illegal sales of these drugs.
Following the successful completion of U.S. trials, the researchers hope to make the polymer available to cancer centers in developing nations for further study.
If the pain treatment trials prove effective, Grossman also expects the implant could be used as an alternative to oral methadone treatment for heroin and morphine addicts in the United States. Current addiction therapy requires daily visits to a clinic for an oral dose of methadone, which occupies opiate receptors in the brain and eliminates narcotic craving and withdrawal symptoms.
"In essence, these people become addicted to the clinic. They cannot travel or seek employment that would require them to be away from the clinic," says Deborah J. Rhodes, M.D., Robert Wood Johnson Fellow at Johns Hopkins and participant in this research. She believes the polymer could be a more effective and less costly method of treating patients who have been maintained successfully on methadone for several years.
Currently, Grossman says, 117,000 people are enrolled in federally funded methadone management programs at an annual cost to the taxpayer of $4,500 per person.
In addition to Grossman and Rhodes, other participants in this research are Glenn J. Lesser, M.D., Kam W. Leong, Ph.D., Hungnan Lo, Ph.D., and Susan L. Eller.