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September 05, 2012 at 07:00 AM EDT
Data Showing Effectiveness of PolyCide Antimicrobial in Surgical Suture Coatings Published in American Chemical Society Journal, Langmuir
PolyCides Outperformed Triclosan as Active Antimicrobial Agent in Suture Coating Study

RADNOR, Pa., Sept. 5, 2012 (GLOBE NEWSWIRE) -- PolyMedix, Inc. (OTCBB:PYMX), a biotechnology company focused on developing innovative approaches to transforming the treatment of infectious diseases, today announced that data showing the effectiveness of one of the company's PolyCide® antimicrobial compounds in laboratory testing of suture coatings were published in the September issue of Langmuir, an American Chemical Society publication. PolyCides are PolyMedix's synthetic antimicrobial compounds that mimic the antimicrobial mechanism of the body's natural defenses against dangerous pathogens and that have been developed as additives to materials in order to make the materials self-sterilizing.

According to recently published research conducted by Johns Hopkins, each year, about 500,000 patients in the United States develop surgical site infections (SSI), which account for more than 10,000 deaths.1

"There is a growing need for effective and safe alternatives to impart antimicrobial properties to medical devices," commented, Dr. Richard Scott, Vice President of Research at PolyMedix. "One currently available antimicrobial suture contains triclosan, an agent which has limited coverage2, documented resistance3 and slow bacterial killing rates4. Our PolyCide compounds have a distinct mechanism of action designed to rapidly kill bacteria and make bacterial resistance unlikely to develop and, in other studies, have demonstrated a broad spectrum of activity. We believe that our PolyCides could play an important role in reducing the incidence of surgical site infections, a potentially serious and expensive medical problem."

The data published in Langmuir was the result of research conducted in collaboration with Dr. Gregory Tew at the University of Massachusetts, Amherst. Dr. Tew is a member of PolyMedix's Scientific Advisory Board. In laboratory tests, the activity of one PolyCide compound, PAMBM (also known as PMX-50003), in antimicrobial suture coatings was compared to that of triclosan. Triclosan is the active ingredient in the most commonly used antimicrobial surgical suture, Vicryl Plus Antimicrobial Suture (VPAS). The results of the research showed:

  • Suture coatings containing the PolyCide outperformed VPAS coatings containing similar concentrations of triclosan in terms of bacterial killing. Ineffective killing was observed with triclosan coatings, whereas greater than 99% reductions in bacterial numbers were demonstrated with coatings containing 1.6% to 2.4% by weight of the PolyCide.
  • The PolyCide rapidly killed (direct bactericidal action) one of the most common pathogens associated with surgical site infections, S. aureus, whereas triclosan was only bacteriostatic (inhibited bacterial reproduction).
  • Calcium stearate, the anionic lubricant in the commercial VPAS coating, did not interfere with the antimicrobial activity of the PolyCide.

Dr. Tew commented, "It is exciting to see that the PolyCide outperformed triclosan in these studies. These data support efforts to expand and advance the development of PolyCide compounds for wound care applications to improve infection control. We are excited about these results and the potential to develop the PolyCide materials for antimicrobial sutures and other medical devices."

The PolyCide compounds are synthetic mimetics of the host-defense proteins, and employ the same mechanism of action that directly and selectively targets and disrupts the bacterial cell membrane. The PolyCides are members of a new class of antimicrobial agents, called defensin-mimetics. Host defense proteins represent one of the oldest and most effective antimicrobial defense systems found in humans and virtually all living creatures. The PolyCides share the same principals for activity as PolyMedix's therapeutic defensin-mimetic antibiotic compounds, including the lead compound, brilacidin, a systemic antibiotic agent which recently successfully completed a Phase 2 clinical trial for the treatment of Staph infections, including MRSA.

The PolyCide research was supported by a grant PolyMedix received from the National Science Foundation to support the development of antimicrobial sutures (NSF SBIR Award 1013835). The content of the Langmuir article is solely the responsibility of the authors and does not necessarily represent the official views of the National Science Foundation.

About the PolyCides

The PolyCides are a series of proprietary PolyMedix compounds which are members of a new class of antimicrobials known as defensin-mimetics. Among the PolyCides are polymers, oligomers, and small molecules designed to mimic the activity of human host-defense proteins, the body's natural defense against bacterial infections. PolyCides, like natural host-defense proteins, kill bacteria by directly targeting bacterial membranes and disrupting them. Widespread resistance to this mechanism of action has not developed despite being used by humans and many other forms of life to fight deadly bacteria for millions of years. Because of this, it is believed that resistance is unlikely to develop to the PolyCides and PolyMedix's other defensin-mimetics.

The PolyCides share the same principals for activity but are chemically distinct from brilacidin, PolyMedix's lead compound, which is being developed as a therapeutic agent for the treatment of systemic infections. PolyMedix recently completed and announced positive results from a Phase 2 clinical trial with brilacidin as an intravenous treatment in patients with ABSSSI.

The mechanism of action of the PolyCides and all of PolyMedix's defensin-mimetics is due to a specific three-dimensional chemical structure which has positively charged properties on one side of the molecule, and hydrophobic (water-avoiding or fat-seeking) properties on the other side. This structure is called facially amphiphilic. PolyCide polymers like PAMBM (PMX-50003) have repeating amphiphilic units arrayed like beads on a chain, which provides the antimicrobial action.

In laboratory studies conducted by PolyMedix and its collaborators, the PolyCides have shown antimicrobial activity in a variety of studies when both applied as coatings to materials, and when incorporated into the materials themselves. The PolyCides have been applied to or incorporated in a range of materials including PVC, polyurethane, silicone, and others. As with brilacidin and other PolyMedix defensin-mimetics, bacterial resistance to the PolyCides has not been observed in multiple serial passage laboratory experiments.

Significant additional work would be required, including clinical trials, and regulatory agency approvals including from the Food and Drug Administration, before the PolyCides could be commercially available.

About PolyMedix, Inc.

PolyMedix is a clinical stage biotechnology company dedicated to transforming the treatment of infectious diseases. PolyMedix is developing a new class of antibiotics – defensin-mimetics – for the treatment of serious, life-threatening infections which often develop resistance to currently available antibiotics. PolyMedix's compounds are designed to imitate the mechanism of action of host defense proteins, which contribute to natural human immunity. In contrast to existing antibiotics, our lead antibiotic compound, brilacidin (formerly PMX-30063), was designed to exploit a method of bacterial cell killing, via biophysical membrane attack, against which bacteria have not shown development of resistance in multiple preclinical studies. Brilacidin showed efficacy similar to an active control, and was safely administered in a Phase 2 clinical trial in patients with acute bacterial skin and skin structure infections (ABSSSI) caused by Staph aureus bacteria (including methicillin-resistant Staphylococcus aureus (MRSA)). PolyMedix has plans for a Phase 2B dose optimization study with brilacidin in ABSSSI patients and to develop brilacidin as a topical treatment for oral mucositis, a common and often debilitating complication of cancer treatments.

PolyMedix has internally developed an extensive pipeline of compounds including other defensin-mimetic antimicrobials for infectious diseases such as Gram-negative pathogens, fungal infections, and malaria; PolyCides®, antimicrobial additives to materials to create self-sterilizing products and surfaces; and delparantag (formerly PMX-60056), an anticoagulant reversing agent. PolyMedix's compounds have been internally discovered using a proprietary drug design technology. 

For more information, please visit our website at www.polymedix.com.

The PolyMedix, Inc. logo is available at http://www.globenewswire.com/newsroom/prs/?pkgid=10449

References:

1http://www.hopkinsmedicine.org/news/media/releases/surgical_site_infections_more_likely_in_patients_with_history_of_skin_infection

2McDonnell G, Russell AD: Antiseptics and disinfectants: activity, action, and resistance. Clin Microbiol Rev 1999, 12:147-179.

3Microb Drug Resist. 2006;12(2):83-90. Triclosan and antimicrobial resistance in bacteria: an overview. Yazdankhah SP, Scheie AA, Hoiby EA, Lunestad BT, Heir E, Fotland TO, Naterstad K, Kruse H.

4Li Yan, Kumar Kushi N, Dabkowski, Jeffrey M, Corrigan Meagan, Scott Richard W., Nusslein Klaus, Tew Gregory N. New Bactericidal Surgical Suture Coating. Langmuir 2012, 12134-12139.

This press release contains forward-looking statements made pursuant to the safe harbor provisions of the Private Securities Litigation Reform Act of 1995 that involve risks, uncertainties and assumptions that could cause PolyMedix's actual results and experience to differ materially from anticipated results and expectations expressed in these forward looking statements. PolyMedix has in some cases identified forward-looking statements by using words such as "anticipates," "believes," "hopes," "estimates," "looks," "expects," "plans," "intends," "goal," "potential," "may," "suggest," and similar expressions. Among other factors that could cause actual results to differ materially from those expressed in forward-looking statements are PolyMedix's need for, and the availability of, substantial capital to fund its operations, planned clinical trials and research and development, and the fact that PolyMedix's compounds may not successfully complete pre-clinical or clinical testing, or be granted regulatory approval to be sold and marketed in the United States or elsewhere. A more complete description of these risk factors is included in PolyMedix's filings with the Securities and Exchange Commission. You should not place undue reliance on any forward-looking statements. PolyMedix undertakes no obligation to release publicly the results of any revisions to any such forward-looking statements that may be made to reflect events or circumstances after the date of this press release or to reflect the occurrence of unanticipated events, except as required by applicable law or regulation.

CONTACT: Lisa Caperelli
         Director, Investor Relations & Corporate Communications
         484-598-2406
         lcaperelli@polymedix.com
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