Technical Field The invention generally relates to an anhydrous and hydrophilic agent for killing lice, especially the head louse (Pediculus capitis) based on anhydrous glycerol.

It further preferably relates to an agent comprising a mixture of this anhydrous and hydrophilic agent and natural biocide(s) and repellent(s). State of the Art

Worldwide occurence of lice has not even been virtually affected by the massive use of highly efficient insecticides. However, in the course of years, a number of insecticides have had to be excluded from use for toxicological reasons. Toxicologically suitable insecticides have gradually proved to lack functionality due to resistance of lice to these substances. At present, no therapeutical preparation is registered that would contain a synthetic insecticide as the active ingredient. Natural substances as aromatic oils and essences are reported as substances having moderate insecticidal or enzymatic effects and these characteristics are the reason for their use in cosmetic preparations with a so-called secondary anti-parasitic effect. However, the number of clinical studies on these natural substances the effect of which consists in blocking of the vital functions of lice is very limited. Practical application of preparations based on natural substances is very frequently problematic and their intensive application in the population of children also causes increasing resistance of lice. Currently, the following methods are used for killing lice:

Asphyxia (choking): Alternative so-called medical agents with physical or physicochemical effects with minimal risks of the development of resistance are recommended for killing lice. Medical agents with physical effects are formulated with the objective to cause asphyxia in lice and their development stages. Kerosene was used to cause asphyxia, being later replaced with agents based on highly hydrophobic oils of the synthetic or natural origin as are e.g. Dimethicon silicone oils or vegetable and animal oils. However, agents that are exclusively made of oils are not comfortable and are difficult to remove from hair. Agents where hydrophobic oils are emulsified in aqueous solutions together with organic surfactants, alcohols, glycols (among other things with glycerol as well), aromatic, preserving and shampooing substances are substantially more practical. However, the emulsification treatment of oil with water reduces the effect of the oil on lice and the application time of the preparation is extended up to 12 hours while it must be applied repeatedly. Hydrophobic oils are also diluted with hydrophilic diluents based on anhydrous alcohols, glycols as well as glycerol together with surfactants, the active ingredient being always oil or natural oil essences.

A relatively new approach in this field consists in the use of nanoparticles of silicon dioxide that are dispersed in the hydrophilic environment of an aqueous solution of glycols, alcohols, glycerol, surfactants and polymeric substances. Silicon dioxide nanoparticles are reported to be an active ingredient for inducing asphyxia in lice. However, the comparative in vitro test in accordance with this invention does not make it possible to estimate the impact of the preparation on the quality of hair and skin.

Chemical eradication: Most preparations using the principle of asphyxia exhibit poor results concerning eradication of nits and therefore substances are used that chemically prevent the development of nits or cause their destruction. These are substances of the enzymatic character that block the production of chitin of the nit frames or simple organic acids (acetic or formic acid), which should dissolve chitin. However, the disclosed concentrations of the acids are very low for the given purpose or so high that their use would be drastic.

Dehydration: An elevated temperature and low relative humidity of the air is a generally known and very efficient physical method of louse eradication. The above mentioned principle of physical dehydration has been patented many times in the form of various thermal combs. However, the degree of chemical treatment of hair will have its limits, mainly in the area of the skin at the hair follicles. Dehydration as a method of removing hair parasites has also been proposed with the use of powders of anhydrous substances that strongly absorb water. The dehydration effect on lice is probably also achieved with alcohol. Generally, the possibilities of using pure ethanol are mentioned, applied with a soaking or combing method. However, the use of pure alcohol is not recommended from the dermatological and fire- protection point of view. Therefore, patented preparations are formulated as alcoholised gels. A current problem in the field of eradication of lice consists in high requirements for the active ingredients of the preparations for their killing. Active ingredients are subject to approval by responsible authorities and one of the conditions of their use is that they must be included in the category of substances that are usable in pharmacy (referred to as PhEur).

Summary of the invention

This condition is met and the above mentioned drawbacks are eliminated or significantly limited by a lice killing agent in accordance with this invention the principle of which is that the agent does not contain water, is hydrophilic and its effect is guaranteed by anhydrous glycerol.

This means that the object of the invention is a lice killing agent that comprises up to 100% wt. of anhydrous glycerol.

The anhydrous glycerol is 1 ,2,2-propanetriol in the pharmaceutical (PhEur) or cosmetic (ΓΝΟ) grade with the maximum content of 1% wt. of water, based on glycerol. The agent in accordance with this invention preferably comprises from 98.5 to 99.95% wt. of anhydrous glycerol and from 0.05 to 1.5% wt. of at least one substance with biocidal or repellent effects.

The substance with biocidal and/or repellent effects is preferably a monoterpenic alkanol, more preferably a plant extract with biocidal and repellent effects, e.g. geraniol or citronellol, pure or in a mixture.

But biocidal and repellent substances as e.g. terpinol, rhodinol or nerol etc., or their mixtures can be used as well.

The advantage of using glycerol and a plant extract with biocidal and repellent effects, e.g. geraniol or citronellol in the agent as the active ingredients is indisputable according to the invention because glycerol has a global status of a non-toxic substance without any influence on human health and the plant extracts with biocidal and repellent effects as geraniol or citronellol, are also friendly to human health. The agent may further, according to the invention, comprise substances adjusting the viscosity and surface tension of the agent. The total content of the additives can be from 0 to 40% wt., based on the total weight of the agent, and these substances must not introduce water into the agent.

The viscosity of the agent can be adjusted as necessary preferably with anhydrous ethanol, propanol, butanol, their isomers and/or their mutual mixture, the substances exhibiting the PhEur quality and being used in the quantity from 15 to 35% wt., preferably from 20 to 30% wt. based on the total weight of the agent.

The most preferable additive for viscosity adjustment is 2-propanol.

The surface tension of the agent can be reduced with a suitable surfactant that is well soluble in the agent and shows the pharmaceutical (PhEur) or cosmetic (INCI) quality, e.g. glucosides, polysorbates, polyoxyethylene derivatives, fatty alcohols and others, in a quantity from 0 to 5% wt., based on the total weight of the agent; preferably, this additive according to the invention is selected from the group comprising glucosides, polysorbates and/or polyoxyethylene derivatives of fatty alcohols, more preferably it is anhydrous 2-propanol, decyl glucoside and/or polyoxyethylene (20) sorbitan monolaurate.

According to the invention, the agent preferably comprises up to 33.5% wt. of an additive for viscosity adjustment, up to 5% wt. of an additive for adjustment of the surface tension of the agent, up to 1.5% wt. of at least one substance with biocidal and repellent effects, the rest to 100% wt. is anhydrous glycerol, all components are based on the total weight of the agent.

Anhydrous glycerol in the PhEur quality can be applied on all parts of the human body surface, incl. mucous membranes, geraniol or citronellol can also be applied on the skin without any negative impact in a diluted state. The fatal effect of the agent on lice in accordance with this invention is derived from the physicochemical characteristics of anhydrous glycerol (1,2,3 propanetriol, CAS register 56-81-5) and is reinforced by the biocidal effect of the plant extracts geraniol (CAS 106-24-1) and/or citronellol (CAS 106-22- 9). Anhydrous glycerol is a hydrophilic liquid having high viscosity (1.49 Pa.s) and the boiling point of 290 °C with a strong dehydration effect on its environment. The relative humidity over anhydrous glycerol is zero. Anhydrous glycerol usually wets well and interacts with skin keratin in such a way that water of the protein structure of keratin is replaced with glycerol, which eliminates the protection function of keratin and subsequently enables dehydration of subcutaneous cells. The said dehydration mechanism is reversible in the presence of water and achieves a degree that is proportional to the water content in glycerol. Since it is a well-known fact that the body surface of lice, the lid of the nit frame and the adhesive between the nit and the hair are made up of keratin, it was a logical step to start research of the influence of anhydrous glycerol on the vital functions of the development stages of lice with the aim to verify to what extent the said dehydration mechanism is applicable to lice. Geraniol and citronellol belong to substances with biocidal and repellent effects that reinforce the destructive function of anhydrous glycerol and in addition they virtually eliminate the return of parasites (lice) to the treated places thanks to their strong repellent effects.

The agent can further preferably contain any anhydrous substance ensuring stability of the anhydrous substance during its storage and application, as e.g. dried bentonite or powdered Aerosil.

Examples

Laboratory in vitro tests:

Procedure: Lice obtained by delousing with a comb were immediately put on a carrier glass, the agent in accordance with this invention was dropped onto them and the moment of the loss of motility of the lice was subjectively determined with the use of a microscope. The time determined this way was defined as the time necessary to kill the lice for a particular sample of the agent.

In vivo tests:

Standard procedure: The agent in accordance with this invention is thoroughly rubbed into dry hair infested with lice, the hair is covered with an impermeable head cover and the mixture is left to act for 60 minutes. Then, the hair is washed with water and dried. The result of the delousing was monitored for 10 days while cases with zero recurrence of infestation with lice out of a sample of 10 children aged 4-14 was considered as 100% success rate of the agent. Example 1

Composition: Anhydrous glycerol, PhEur quality, no additives.

Result: The time necessary to kill the lice lies within the interval of 15 to 45 minutes.

Example 2

Composition: 70% wt. of anhydrous glycerol, PhEur quality

30% wt. of anhydrous 2-propanol, PhEur quality

Result: The time necessary to kill the lice lies within the interval of 15 to 30 minutes.

Example 3

Composition: 69% wt. of anhydrous glycerol, PhEur quality

30%) wt. of anhydrous 2-propanol, PhEur quality

1%) wt. of decyl glucoside, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency. This result shows that the agent efficiently destroys nits as well.

Example 4

Composition: 73% wt. of anhydrous glycerol, PhEur quality

25%> wt. of anhydrous ethanol, PhEur quality

2% wt. of polyoxyethylene (20) sorbitan monolaurate

Result: In the said composition, the agent exhibits 100% efficiency against lice and nits.

Example 5

Composition: 99.95% wt. of anhydrous glycerol, PhEur quality

0.05% wt. of geraniol, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency. This result shows that the agent efficiently destroys nits as well. Example 6

Composition: 99 A% wt. of anhydrous glycerol, PhEur quality

0.6%) wt. of geraniol (saturated solution), INCI quality

Result: In the said composition, the agent exhibits 100%) efficiency. This result shows that the agent efficiently destroys nits as well. Example 7

Composition: 70% wt. of anhydrous glycerol, PhEur quality

29% wt. of anhydrous 2-propanol, PhEur quality

1% wt. of geraniol, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency. This result shows that the agent efficiently destroys nits as well.

Example 8

Composition: 69% wt. of anhydrous glycerol, PhEur quality

29% wt. of anhydrous 2-propanol, PhEur quality

1%» wt. of geraniol, INCI quality

1%> wt. of decyl glucoside, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency. This result shows that the agent efficiently destroys nits as well.

Example 9

Composition: 75% wt. of anhydrous glycerol, PhEur quality

22% wt. of anhydrous 2-propanol, PhEur quality

2% wt. of polyoxyethylene (20) sorbitan monolaurate

1% wt. of geraniol, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency against lice and nits.

Example 10

Composition: 99.4%) wt. of anhydrous glycerol, PhEur quality

0.3%) wt. of geraniol, INCI quality

0.3% wt. of citronellol, INCI quality

Result: In the said composition, the agent exhibits 100%) efficiency. This result shows that the agent efficiently destroys nits as well.

Example 11

Composition: 70% wt. of anhydrous glycerol, PhEur quality

29% wt. of anhydrous 2-propanol, PhEur quality

1 % wt. of citronellol, INCI quality Result: In the said composition, the agent exhibits 100% efficiency. This result shows that the agent efficiently destroys nits as well.

Example 12

Composition: 69% wt. of anhydrous glycerol, PhEur quality

29% wt. of anhydrous 2-propanol, PhEur quality

1% wt. of citronellol, INCI quality

1% wt. of decyl glucoside, INCI quality

Result: In the said composition, the agent exhibits 100%) efficiency. This result shows that the agent efficiently destroys nits as well.

Example 13

Composition: 75% wt. of anhydrous glycerol, PhEur quality

22% wt. of anhydrous 2-propanol, PhEur quality

2% wt. of polyoxyethylene (20) sorbitan monolaurate

1%> wt. of citronellol, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency against lice and nits.

Example 14

Composition: 75% wt. of anhydrous glycerol, PhEur quality

22%) wt. of anhydrous 2-propanol, PhEur quality

2% wt. of polyoxyethylene (20) sorbitan monolaurate

0.5%) wt. of citronellol, INCI quality

0,5%) wt. of geraniol, INCI quality

Result: In the said composition, the agent exhibits 100% efficiency against lice and nits.

For a skilled person, it would not be difficult to create further modifications without variation of the basic concept of the invention and without diverging from its scope as it is protected in the claims below.

Industrial applicability

The agent exhibits up to 100% efficiency of killing head louse from the hair and skin. The high efficiency of the anhydrous agent on the basis of glycerol and preferably with an addition of geraniol and/or citronellol in accordance with this invention against all the development stages has been verified experimentally and in vivo. A considerable benefit of the agent in accordance with this invention is the fact that the application of the agent is comfortable, it is friendly to human health, i.e. does not irritate the skin, does not damage hair and the nit frames are easy to remove from hair.

Further, the agent in accordance with the invention is not costly and does not load the environment in any manner.