Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Implant or insert
Reexamination Certificate
2003-02-25
2004-07-27
Page, Thurman K. (Department: 1615)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Implant or insert
C424S078020, C424S078080
Reexamination Certificate
active
06767549
ABSTRACT:
BACKGROUND OF THE INVENTION
A number of short (ca. 50 amino acid residues or fewer) linear or cyclic cytotoxic peptides have been isolated recently from a variety of sources. These include mellitin, from bee venom, the magainins, from frog skin, and cecropins, from insects (Maloy, et al.,
Biopolymers
(
Peptide Science
) 37: 105-122 (1995)). Although of widely varying peptide sequences and structures, these peptides all contain multiple lysine and arginine residues, and, at physiological pH, carry a net positive charge. They also form amphipathic structures wherein one portion of the structure is hydrophilic while the other portion is hydrophobic.
The peptides appear to act solely by direct lysis of the cell membrane (Maloy et al., supra (1995)). In the current model, cell lysis is initiated by the electrostatic attraction of the positive charge on the peptide to the negative phosphate head groups at the exterior surface of the membrane phospholipid bilayer. This interaction leads to insertion of the hydrophobic portion of the protein into the membrane, thereby disrupting the membrane structure. The lytic peptides are, in general, more active against prokaryotic cells, such as bacteria and fungi, than eukaryotic cells. This has led to interest in these peptides as potential agents for the treatment of infections in humans (Maloy et al., supra (1995); Arrowood et al.,
J. Protozool.
38: 161S-163S (1991); Haynie et al.,
Antimicrob. Agents Chemotherapy
39: 301-307 (1995).
The natural cytotoxic peptides, however, suffer from several disadvantages with respect to their use as human therapeutic agents. First, it appears that these peptides have evolved to act at high concentration at specific localized sites. Thus, when administered as a drug, the dosage necessary to attain an effective concentration at site of infection can be prohibitively high. A second disadvantage is the difficulty of isolating useful amounts of these peptides from the natural sources, along with the high cost of synthesizing useful amounts of peptides in this size regime. Finally, these compounds, like other peptides, are degraded in the gastrointestinal tract, and, thus, cannot be administered orally.
There is a need for anti-microbial agents which possess the broad activity spectrum of the natural cytotoxic peptides, but are inexpensive to produce, can be administered orally and have lower concentration requirements for therapeutic activity.
SUMMARY OF THE INVENTION
One aspect of the present invention is a method for treating a microbial infection in a mammal, comprising administering to the mammal a therapeutically effective amount of a polymer having an amine or ammonium group connected to the polymer backbone by an aliphatic spacer group.
The polymer to be administered can be a homopolymer or a copolymer. In one embodiment, the polymer further includes a monomer comprising a hydrophobic group, such as an aryl group or a normal or branched C
3
-C
18
-alkyl group.
The polymer to be administered can, optionally, further include a monomer comprising a neutral hydrophilic group, such as a hydroxyl group or an amide group.
Another aspect of the invention is a method for treating a microbial infection in a mammal, such as a human, comprising administering to the mammal a therapeutically effective amount of a polymer comprising a polymethylene backbone which is interrupted at one or more points by a quaternary ammonium group.
The present method has several advantages. For example, the polymers employed are easily prepared using standard techniques of polymer synthesis and inexpensive starting materials. The polymers will not be substantially degraded in the digestive tract and, therefore, can be administered orally. Polymer compositions can also be readily varied, to optimize properties such as solubility or water swellability and antimicrobial activity. Finally, the polymers to be administered include amine or ammonium functional groups attached to the polymer backbone via aliphatic spacer groups. The structural flexibility of such spacer groups minimizes backbone constraints on the interaction of the ammonium groups with anionic targets.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a method for preventing or treating a microbial infection in a mammal, such as a human, by administering to the mammal a therapeutically effective amount of a polymer comprising a plurality of amino or ammonium groups which are attached to the polymer backbone via aliphatic spacer groups.
As used herein, a “therapeutically effective amount” is an amount sufficient to inhibit, partially or totally, a microbial infection or to reverse development of a microbial infection or prevent or reduce its further progression. The term “polymer” refers to a macromolecule comprising a plurality of repeat units or monomers. The term includes homopolymers, which are formed from a singly type of monomer, and copolymers, which are formed of two or more different monomers. A “terpolymer” is a copolymer formed from three different monomers. The term polymer, as used herein, is intended to exclude proteins, peptides, polypeptides and proteinaceous materials.
As used herein, the term “polymer backbone” or “backbone” refers to that portion of the polymer which is a continuous chain, comprising the bonds which are formed between monomers upon polymerization. The composition of the polymer backbone can be described in terms of the identity of the monomers from which it is formed, without regard to the composition of branches, or side chains, off of the polymer backbone. Thus, a poly(acrylamide) polymer is said to have a poly(acrylamide) backbone, without regard to the substituents on the acrylamide nitrogen atom, which are components of the polymer side chains. A poly(acrylamide-co-styrene) copolymer, for example, is said to have a mixed acrylamide/styrene backbone.
The term “polymer side chain” or “side chain” refers to the portion of a monomer which, following polymerization, forms a branch off of the polymer backbone. In a homopolymer all of the polymer side chains are identical. A copolymer can comprise two or more distinct side chains. When a side chain comprises an ionic unit, for example, the ionic unit depends from, or is a substituent of, the polymer backbone, and is referred to as a “pendant ionic unit”. The term “spacer group”, as used herein, refers to a polyvalent molecular fragment which is a component of a polymer side chain and connects a pendant moiety to the polymer backbone. The term “aliphatic spacer group” refers to a spacer group which does not include an aromatic unit, such as a phenylene unit.
The term “addition polymer”, as used herein, is a polymer formed by the addition of monomers without the consequent release of a small molecule. A common type of addition polymer is formed by polymerizing olefinic monomers, wherein monomers are joined by the formation of a carbon-carbon bonds between monomers, without the loss of any atoms which compose the unreacted monomers.
The term “monomer”, as used herein, refers to both (a) a single molecule comprising one or more polymerizable functional groups prior to or following polymerization, and (b) a repeat unit of a polymer. An unpolymerized monomer capable of addition polymerization, can, for example, comprise an olefinic bond which is lost upon polymerization.
The quantity of a given polymer to be administered will be determined on an individual basis and will be determined, at least in part, by consideration of the individual's size, the severity of symptoms to be treated and the result sought. The polymer can be administered alone or in a pharmaceutical composition comprising the polymer, an acceptable carrier or diluent and, optionally, one or more additional drugs.
The polymers can be administered, for example, topically, orally, intranasally, or rectally. The form in which the agent is administered, for example, powder, tablet, capsule, solution, or emulsion, depends in part on the route by which it is administered. The therapeutically effective amount
Holmes-Farley Stephen Randall
Mandeville, III W. Harry
Neenan Thomas X.
Bennett Rachel M.
Genzyme Corporation
Hamilton, Brook, Smith and Reynolds, P.C.
Page Thurman K.
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