Liposome technology is advancing on several fronts, withnewly issued patents for the use of the fatty microspheres tolessen the number of injections for allergy sufferers, and todeliver drugs deep into the lungs.
Researchers, meanwhile, are reporting that the liposomes canget cancer drugs to tumors.
Liposomes are spherical shells of a double layer ofphospholipid, made to precise sizes and solubilities to deliverdesired drugs at controlled rates.
Allergy Immuno Technologies Inc. on Sept. 17 received patentNo. 5,049,390 for its conventional liposomes, which thecompany has formulated to treat allergies mediated by THE IgEclass of antibodies.
The most common allergies -- those to molds, foods andseasonal pollens -- are mediated by IgE, said companyresearcher Irene Haydick. The strategy will be to injectliposomes containing allergen into muscles or under the skin,with sustained release to follow. Traditional desensitizingshots inject allergen into the skin and must be repeated.
Allergy Immuno Technologies, listed on the OTC "pink sheets,"is a subsidiary of Biomerica Inc. (NASDAQ:BMRA). Both arelocated in Newport Beach, Calif.
Liposome Technology Inc. of Menlo Park, Calif., received patentNo. 5,049,389 on its liposomes made of cholesterol. Theformula will allow delivery of steroids deep into the lung, saidFrank Martin, vice president of research.
Beclomethasone, used to treat asthma and other inflammatorydiseases of the lung, may now reach the alveolar air-exchangesurfaces without "flipping out" of the liposome immediately,said Martin. "You don't want to dump the dose and get systemicuptake," Martin told BioWorld, since steroids interfere withadrenal and other critical functions.
Research Development Foundation of Carson City, Nev.,meanwhile, received patent Number 5,049,388 for smallparticle, aerosol liposomes to ferry drugs into the lungs.
A spokesman for the not-for-profit foundation, which grantsmoney for research, was unavailable to comment on itstechnology or the possible overlap with Liposome Technology'spatent.
Martin said Liposome Technology (NASDAQ:LTIZ) has patentspending on the aerosol method as well. "Whether we will have aconflict, I don't know," he said.
Delivery of chemotherapy to cancers is another front on whichliposomes are charting progress. Liposome Technology's"stealth" liposomes are showing appropriately long persistencein patients' bloodstreams in Phase I trials in Israel, Martinsaid, while animal data to be published soon in the Proceedingsof the National Academy of Sciences show accumulation intumors of the cancer drug doxorubicin delivered by theliposomes.
Meanwhile, Japanese researchers at the University ofTokushima have reported on an anti-cancer therapy using"microcapsules" one-twentieth the size of conventionalliposomes. The therapy resulted in a high level of accumulationin rat cancers, with half or less of the liver uptake seen withexisting liposomes.
-- Roberta Friedman, Ph.D. Special to BioWorld
(c) 1997 American Health Consultants. All rights reserved.