The federal government approved a drug Tuesday that offers a new way of fighting severe pain--an option for patients who no longer benefit from morphine and other traditional pain medications, including people with AIDS and cancer. It's the first in a new class of drug known as a N-type calcium channel blocker that selectively obstructs the nerve channels responsible for transmitting pain signals. It will be marketed as Prialt and should be available by the end of January.
"When you've taken all the kinds of pain medication that there is and you still have pain, that is a very frightening situation," said Lars Ekman, president of research and development for the drug's Ireland-based manufacturer, Elan. "When you have that kind of pain, there is nowhere to go."
Morphine is the standard treatment for severe pain from cancer, AIDS, amputations, and other significant illnesses, but its effects eventually wear off, requiring the dosage to be increased. At some point many patients switch from taking medication by mouth or by injection to a microinfusion pump implanted under the skin that delivers drugs directly into the fluid surrounding the spinal cord. Ekman said about 35,000 to 50,000 Americans have these pumps now. The Food and Drug Administration approved Prialt for patients who are already using these pumps but not getting effective relief from them, or who cannot tolerate the available treatments. This is the first new drug in 20 years to treat pain using such a pump.
Prialt has been studied in patients with cancer, AIDS, and other sources of chronic pain, such as back pain. More than 1,200 patients took part in three clinical trials. There are side effects, and the FDA gave the drug a "black box" warning--the government's strongest warning short of a ban. Side effects may include dizziness, drowsiness, and altered mental state, with patients confused at times. Despite the side effects, the drug was approved because there are no other options for these patients and the benefits outweighed the risks, said Robert Meyer, director of the FDA's Office of Drug Evaluation II. "Because this is such an important patient population, where they have such pain and they have so few options, we felt this drug does offer some real gains," he said.
The idea for the drug came from a South Pacific snail called the Conus magus, which paralyzes its victims with venom after capturing them, Elan officials said. Researchers set out learning how to develop a drug based on this venom and eventually copied the amino acid sequence. (AP)