Sep. 24, 2003 University of South Florida chemists who recently patented a new class of synthetic antibiotics for killing drug-resistant bacteria have also developed a better (and smaller) way of getting drugs to a target. Using nanotechnology - the big science of making small things - their antibiotics now can ride into bacteria cells on nano-sized, spherical vehicles one millionth the size of a pinhead.
"We feel that this technology will afford many benefits down the road," explains says Edward Turos, a professor in USF's Department of Chemistry and one of several USF chemists working in drug discovery as a member of the Drug Discovery Program at the H. Lee Moffitt Cancer Center and Research Institute. “For example, patients battling serious hospital infections may be treated with much smaller doses of drug, potentially reducing unwanted side effects, such as toxicity and allergic responses, as well as the onset of further drug resistance.”
The new synthetic antibiotics, members of a family of antibiotics called beta-lactams, of which penicillin is also a member, uses a new mode of action to stop methicillin-resistant staph (MRSA) bacteria dead in their tracks. MRSA bacteria are responsible for most of the hospital-borne infections becoming resistant to even the most powerful antibiotics. The new antibiotics attack these bacteria selectively and with more power than vancomycin, the drug now used as the last line of resort for MRSA infections.
"Antibiotic resistance is a huge problem worldwide, and there has been an alarming increase in antibiotic resistance just in the past several years," advises Turos. "What is most important is that this new class of antibiotics acts particularly well on the nastiest strains of staph bacteria, for which there may not be any effective treatment."
After creating the new class of antibiotics, the next step for the USF team was to develop a second punch - a tiny drug delivery vehicle that could better carry the antibiotic to the infection site and deliver less drug more effectively. Using a process called "microemulsion polymerization" the team created nano-sized plastic spheres with drugs chemically bonded to their surface. The nanoballs allow the drug to be dissolved in water, dramatically improving performance. The nano-sized plastic balls are many times smaller than the bacteria cells and bacteria willingly gobble them up as potential food. But, once inside the cell, the balls release high concentrations of the drug where it wreaks havoc on the internal machinery of the cell.
"The delivery of pharmaceutical agents that are water-insoluble to targets within the human body has always been a challenge," says Turos, whose work is funded by the National Institutes of Health. "Many potentially valuable drugs that look promising are, unfortunately, not very soluble in water and their clinical uses are greatly restricted because they are unable to get into the bloodstream.”
The new drug delivery vehicles that improve drug solubility may open the door to revolutionary changes in medicine, particularly in the detection and treatment of infectious diseases.
“We hope to soon be able to design and custom-prepare nano-sized delivery vehicles of different shapes and sizes and tailor their function to a wide variety of applications in the biomedical and nanotechnology fields," concludes Turos.
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