Drug – bio-affecting and body treating compositions – Designated organic active ingredient containing – Carbohydrate doai
Reexamination Certificate
1999-10-25
2001-11-20
Fonda, Kathleen Kahler (Department: 1623)
Drug, bio-affecting and body treating compositions
Designated organic active ingredient containing
Carbohydrate doai
C424S405000
Reexamination Certificate
active
06319909
ABSTRACT:
The invention relates to an improved process for preparing a liquid iodophore with dextrin and a poly-N-vinyllactam as carrier material.
In the area of skin-safe disinfectants, PVP-iodine is a long-established product which is, however, costly. The preparation of saccharide-containing iodophores by polymerizing vinylpyrrolidone in the presence of the particular oligo- or polysaccharides is moreover disclosed in EP-A-526 800. Although products of this type are less costly than PVP-iodine, they do not comply with the requirements to be met by PVP-iodine. In addition, they have not to date been pharmacologically accepted.
WO 9528841 describes the preparation of iodophores from poly-N-vinyllactam and dextrin. For applications of the iodophore in liquid form, it is more expedient, simple and economic to carry out the process described in WO 9528841 in aqueous solution. However, preparation in pure aqueous solution results in highly viscous suspensions with a high solids content. An additional fault is the formation of iodine sublimate which may be observed. If, for example, a mixture of 10% by weight of polyvinylpyrrolidone (K value 30), 15% by weight of dextrin with a DE value of 17 to 19, 6% by weight of iodine, 0.3% by weight of ammonium formate and 68.7% by weight of water is heated with stirring over the course of four hours to 80° C., and after a further eight hours at 80° C., cooled to room temperature, the result is a highly viscous suspension (viscosity: 12300 mPas, see below for measurement) with 0.5% by weight of iodine sublimate and about 10% by weight of solid residue. The large amount of iodine-containing residue, the iodine sublimate and the pasty consistency of the resulting product make it appear desirable to find an improved process.
It is an object of the present invention to develop an improved process for the direct preparation of an iodophore solution with poly-N-vinyllactam and dextrin as carriers.
We have found that this object is achieved by a process for preparing liquid iodophores with poly-N-vinyllactams and dextrins as carrier materials, which comprises heating the carrier materials, iodine and iodide ions or, in place of the iodide ions, a reducing agent in aqueous medium in the presence of a monohydric or polyhydric alcohol having 1 to 6 carbon atoms at from 40 to 100° C.
Suitable monohydric or polyhydric alcohols according to the invention are methanol, preferably ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, isopropanol, isobutanol and other branched homologs of said alcohols, ethylene glycol, glycerol or mixtures thereof, with n-propanol being particularly preferred.
The iodophore is prepared by mixing the components and heating them at from 40 to 100, preferably 60 to 95° C. In a preferred variant of the process, the iodine is dissolved in the monohydric or polyhydric alcohol component and added dropwise. The reaction takes from 1 to 30 hours, depending on the amounts employed.
The liquid iodophores have the following composition in particular:
a) 5-60% by weight of polyvinylpyrrolidone or poly-N-vinylcaprolactam,
b) 5-60% by weight of dextrin with a DE value of from 2 to 40,
c) 1-30% by weight of elemental iodine,
d) 0.5-15% by weight of iodide ions,
e) 5-40% by weight of the alcohol component and
f) 20-80% by weight of water,
where the total of components a) to f) equals 100% by weight. Preferred iodophores have a viscosity <1000 mPa.s (25° C.), with a solids content of 25-40% by weight and an available iodine content of 10-18% by weight.
The dextrins are commercially available and can easily be obtained from starch by incomplete hydrolysis with dilute acid, by exposure to heat and by oxidative or enzymatic degradation using amylases.
Starch degradation products obtainable by hydrolysis in aqueous phase and having a weight average molecular weight of from 2500 to 25000 are, in distinction from the torrefaction dextrins, normally referred to as saccharified starches and are commercially obtainable as such.
Saccharified starches of this type differ chemically from the torrefaction dextrins inter alia in that on hydrolytic degradation in aqueous medium (normally suspensions or solutions), which is usually carried out with solids contents of from 10 to 30% by weight and preferably with acid or enzyme catalysis, there is essentially no possibility of recombination and branching, which is manifested not least by different molecular weight distributions.
The preparation of saccharified starches is generally known and is described, inter alia, in Günther Tegge, Stärke und Stärkederivate, Behr's Verlag, Hamburg 1984, page 173 and pages 220 ff, and in EP-A 441 197. The saccharified starches to be used according to the invention are preferably those whose weight average molecular weight M
w
is in the range from 4000 to 16000, particularly preferably in the range from 6500 to 13000.
The saccharified starches to be used according to the invention are normally completely stable in water at room temperature, with the solubility limit usually being above 50% by weight. It is preferred for 10 to 20% by weight, particularly preferably 30 to 40% by weight, solutions to be clear solutions, and not colloidal suspensions, at room temperature.
It is furthermore advisable to employ those saccharified starches to be used according to the invention whose dextrose equivalent DE is from 2 to 40, preferably 10 to 30 and particularly preferably 10 to 20. The DE value characterizes the reducing capacity relative to the reducing capacity of anhydrous dextrose and is determined as specified in DIN 10 308, edition 5.71, of the Deutscher Normenausschuss Lebensmittel und landwirtschaftliche Produkte (cf. also Günther Tegge, Stärke und Stärkederivate, Behr's Verlag, Hamburg 1984, page 305).
Suitable initial starches for preparing the saccharified starches to be used according to the invention are, in principle, all natural starches such as cereals starches (eg. corn, wheat, rice or millet), tuber and root starches (eg. potatoes, cassava roots or arrowroot) or sago starches.
It is a considerable advantage of the saccharified starches to be used according to the invention that, apart from the partial hydrolysis of the initial starch, which can be carried out in a very simple manner, no further chemical modification is required to prepare them for use.
The saccharified starches used in the Examples were the C* PUR products 01906, 01908, 01910, 01915, 01921, 01924, 01932 or 01934 of Cerestar Deutschland GmbH, Krefeld. They all have essentially a bimodal molecular weight distribution and have the following characteristics:
% by weight
Type
M
w
H
<1000
DE
01906
20080
10.9
12.2
2-5
01908
19290
10.0
15.9
8-10
01910
10540-12640
8.5-9.9
24.7-26.4
11-14
01915
6680-8350
6.8-8.4
32.9-34.7
17-19
01921
6700
7.4
39.1
20-23
01924
4730
6.8
53.6
26-30
01932
4500
7.9
63.2
33-35
01934
3000
6.0
68.4
36-39
Determinations of M
n
by vapor pressure osmosis gave the following results for the preferred types 01910 and 01915:
1560 g/mol (1910)
980 g/mol (1915)
H=heterogeneity
M
w
=weight average molecular weight
M
n
=number average molecular weight
DE=dextrose equivalent
To react the iodine and iodide with the carrier in solution, the iodine must be present in homogeneous form. The complex is formed by adding sufficient iodine and iodide for the final mixture to contain from 1 to 30, preferably 1 to 10, % by weight of iodine and 1 mol of iodide per mole of iodine (I
2
). The cation of the iodide is immaterial and is usually sodium or potassium. The iodide can be replaced by an equivalent amount of a reducing agent which reduces iodine to iodide, for example formic acid and its salts, preferably ammonium formate, glucose, ascorbic acid, malonic acid, oxalic acid, ammonium oxalate, if the initial amount of iodine is increased correspondingly. It must be taken into account in this connection that dextrins also have a certain iodine-reducing capacity because of their aldehydic end groups. It has emerged, surprisingly, that it was possible to obtai
Breitenbach Jorg
Ernst Andreas
Sanner Axel
BASF - Aktiengesellschaft
Fonda Kathleen Kahler
Keil & Weinkauf
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