A new drug that may help people with certain types of memory disorders may soon be on the market in this country. The drug, called vinpocetine, appears to improve an individual's ability to acquire new memories and to restore memories that have been disrupted, it was disclosed Monday.
Vinpocetine was first discovered in the early 1970s by chemists at the Gedeon Richter Chemical Works in Budapest, Hungary, and is already being sold in much of the Eastern Bloc, as well as in Mexico, Central America, and Japan.
But most of the earlier studies of the drugs in humans did not have proper controls, according to John Mullane, an executive vice president of Ayerst Laboratories, and it is only recently that sound studies in both humans and animals have been reported.
The first reports of research conducted by Ayerst were made here Monday at a meeting of the American Chemical Society.
Clinical trials by Ayerst and approved by the federal Food and Drug Administration have focused on treatment of patients with multiple-infarct dementia, a brain disorder resulting from a series of small strokes. The disorder affects an estimated 200,000 Americans each year.
"These people suffer damage to many small areas of their brains when blood flow is cut off, often as a complication of hardening of the arteries," Mullane said. "Often they have difficulty both in recalling information and in setting down new memories."
Trials in Europe, some conducted by other companies marketing the drug there, Mullane said, have shown that about 60% to 70% of patients who received vinpocetine after developing multiple-infarct dementia showed at least some improvement in memory and other mental functions, and 20% to 30% showed significant improvement.
The company has just completed a similar study at eight institutions in the United States. Mullane said the results of that study should be available sometime this fall, when it will be reviewed by the FDA. Ayerst hopes to win FDA approval to begin selling the drug for use against multiple-infarct dementia by February, 1987.
There is some evidence also, Mullane said, that vinpocetine could be useful against the symptoms of Alzheimer's disease, which is characterized by, among other problems, loss of memory. Ayerst plans to begin clinical trials of the drug in Alzheimer's patients in mid-1987.
Neuropharmacologist J. M. Ordy of Pennwalt Corp., another drug manufacturer, said at a press conference at the meeting that he is not familiar specifically with the Ayerst trials but that scientists, especially those in Europe, are very enthusiastic about drugs such as vinpocetine, which they call nootropic or brain-stimulating drugs. Many neurologists, he said, are convicnced that even more powerful nootropic drugs will be developed.
Little is known about how vinpocetine--a wholly synthetic chemical that is closely related to compounds obtained from periwinkle--works. The Hungarians originally thought it worked by increasing blood flow to the brain, Mullane said, but that effect lasts for only about 15 minutes.
"The important effect is more likely to be improved use of glucose and other substrates by the brain cells," he said.
Because so little is known about vinpocetine, Ayerst has been studying its effects in animals at the same time it is testing the drug in humans. Psychologist Victor DeNoble of Ayerst Laboratories Research Inc. reported at the meeting that vinpocetine can speed up by about 40% the rate at which rats learn tasks, can block the action of drugs that disrupt memory, and can help the rats retain memories for longer periods.
In one series of tests, for example, DeNoble used a box with two chambers, one lit and one unlit. The rats could be taught fairly easily to stay in the lit chamber.
If the rats were given the drug scopalamine or were given only small amounts of oxygen in the air they breathed, they would forget which chamber to enter. Vinpocetine restored their ability to remember to enter the lit chamber.
Similarly, if the rats were taught to enter the lit chamber and tested again three days later, only about 15 of every 100 rats remembered what they had learned. Among those given vinpocetine, more than 75 out of every 100 remembered.
In a separate series of experiments, DeNoble taught the rats an increasingly complex series of tests. They might, for example, be trained to estimate the passage of 4 seconds. When they learned that, they would then be trained to estimate 8 seconds, and so on.
"At each step of the process," DeNoble said, "the rats learned the new task about 40% faster."
Once the company has learned how vinpocetine works in animals, DeNoble said, "we think that we can develop some much more effective compounds."