Silver sulfadiazine (SSD) preparations are among the best topical antibacterial agents in clinical use for the treatment of infected wounds, especially of burns. However, because SSD is water-insoluble, its most commonly known preparations consist of dispersions with water-soluble cream bases containing, inter alia, emulsifying substances that not only do not contribute to the healing process but frequently even hinder it. Moreover, said known preparations cannot be used in a dry form. Finally the amount of SSD required in said emulsions, as suggested by various manufacturers, is about 318-530 mg in an area of 10.times.10 cm in a 3-5 mm layer. These large amounts of SSD may cause systemic absorption and damage to the wound tissue.
From European Patent Specification B 140,596 there is known a porous complex of a biodegradable fibrous protein, e.g. collagen, with a polyanionic plant, polysaccharide. S.S.D. may be incorporated into the wound contact layer. It should be stressed that there is concerned a complex and not a simple mixture and/or compound which requires the presence of a special polysaccharide. Said polysaccharide gives special properties to the complex which are described and claimed.
Collagen is the major connective tissue structural protein with a variety of biological properties that are intimately involved in all phases of tissue repair processes following injury. The collagen molecule has several hydrophobic domains along its long polypeptide chains which are suitable for hydrophobic interactions with other hydrophobic molecules, such as silver sulfadiazine.
From U.S. Pat. No. 4,581,028 is known an infection-resistant device which is a vascular graft prosthesis for use within the interior of a human or animal body which may comprise collagen and SSD. However, said device cannot be used as a topical preparation. However, the amount of SSD utilised cannot be calculated.
From U.S. Pat. No. 4,599,226 is known a method for preparing animal tissues for use as burn or wound dressings comprising, inter alia, SSD. It is assumed that collagen may be present in the skin tissue utilised. However, nothing can be learned about a topical preparation comprising collagen and SSD.
From DOS3.523.023 A1 is known a collagen sponge comprising 0.5-10 mg of a silver salt which dissolves with difficulty. However, only the use of inorganic silver salts is shown and a very specific method of preparation is exemplified.
It has thus been desirable to find a specific topical preparation which overcomes the above disadvantages, should be easy to prepare and have the required amounts of SSD.