Ectoparasiticidal composition

Abstract

The invention provides for an ectoparasiticidal composition for the effective treatment of infestation of human hair by ectoparasites such as lice and lice eggs. The present composition comprises a polysiloxane active ingredient at 75% to 90% w / v, a first ester at 10% to 17% w / v, a second ester different to the first ester at 2% to 8% w / v, an antioxidant at 0.0001% to 0.1% w / v and a C6-C16 aliphatic alcohol at 0.4% to 2.0% w / v; wherein the polysiloxane may comprise a kinematic viscosity in the range of 10 to 200 mm2 / s. The polysiloxane may comprise dimethiconol, dimethicone or phenyl dimethicone. The first ester may comprise diisopropyl adipate, neopentyl glycol diethylhexanoate or diisostearyl malate and the second ester may comprise diisopropyl sebacate, neopentyl glycol diethylhexanoate or diisostearyl malate. The antioxidant may comprise vitamin E and the C6-C16 aliphatic alcohol may comprise 1-deconol, 1-tetradeconol or dodecanol. The invention further provides for said ectoparasiticidal composition being used in the treatment of infestation in humans by parasites from the families Pediculidae and Pthiridae.

Description

Field of invention The present concept relates to ectoparasiticidal compositions, and in particular, although not exclusively, to a composition for treating lice infestation in humans caused by insects from the families Pediculidae and Pthiridae. Background Lice infestation in humans is generally caused by insects from the families Pediculidae andPthiridas, in particular Pediculus humanus species, Pthiruspubis and Pediculus humanus capitis. Earlier approaches for the treatment of lice were based on pediculicidal toxicants such as Lindane (gamma benzene hexachloride), pyrethrins and Cuprex (a combination of tetrahydronaphthalene, copper oleate and acetone). Because of increased concern with the safety of some of these known extoparasitic toxicants, new replacement compounds were investigated. Later generations of such compositions have been based on siloxanes that have been found effective for treatment of both lice and their ova. Example disclosures include GB 1604853 A and GB 2404587 B. However, there remains opportunity for the improvement of existing head lice treatment compositions with regard to effectiveness in treating infestation including treatment of both lice and their ova. Additionally, treatment with existing compositions over extended periods may be deleterious to the skin / scalp in certain situations. Summary of the invention It is an objective of the present concept to provide a composition suitable for treatment of ectoparasites such as lice and their ova and particularly human hair infestation by such ectoparasites. It is a further objective to provide an effective treatment formulation that may be conveniently administered, remains in position at the skin whilst in contact with the lice and ova without causing skin irritation and / or harm. It is a further specific objective to provide a composition that may be easily and conveniently removed / washed from the skin / scalp by conventional methods such as the application of water and water-mild-surfactant compositions. It is a further specific objective to provide a formulation that minimises environmental toxicological impact with regard to manufacture and disposal after application and treatment. Accordingly, the present concept provides an ectoparasiticidal composition effective for the treatment of human hair infestation by lice and their ova. In particular, the present composition comprises a synergistic combination of ingredients including specifically an ingredient effective to kill lice and their ova and additional components that are effective to provide a formulation that may be conveniently delivered to the skin / scalp, remains in place during treatment, may be washed from the skin / scalp conveniently and is beneficial for skin / scalp health. As will be appreciated, the primary objective of an ectoparasiticidal composition is the rapid and effective treatment of lice and their ova. The present formulation whilst including an effective lice toxic agent, also includes an advantageous combination of esters, antioxidant and alcohol. This has been identified by the inventors for inclusion within an ectoparasiticidal composition that provides a toxicological / physiological effect by interrupting the lice / eggs respiratory system whilst also providing dermatological advantages. Advantageously, an antioxidant is included being preferably a vitamin E based compound such as vitamin E acetate. This has been found to be effective in combination with the recited esters and alcohol to be absorbed into the skin but only within the first two layers of the skin. This provides a protective / southing effect to skin that may be otherwise irritated due to lice infestation. As will be appreciated, lice infestation can be associated with scratching or scrapping of the skin / scalp due to irritation by the lice and the extensive use of lice combs etc. Accordingly, the present formulation provides both a composition effective to kill lice and their ova whilst providing skin southing characteristics. Additionally, the present formulation by the combination of esters and alcohol, at their respective concentrations, provides a sprayable formulation with the desired hydrophobicity to effectively wet the skin / scalp and hair. This has been found to be particularly effective for delivery of the active ingredient to all regions of infestation. Furthermore, including an antioxidant has been found to be particularly beneficial where the formulation is subject to UV radiation, such as when a host spends time outdoors. The antioxidant is effective to preserve the activity of the active agent for the treatment of the lice and their ova and to mitigate UV degradation that may otherwise occur with even relatively short or modest periods of UV exposure while the composition (and in particular active ingredient) is in situ. According to one aspect of the present concept there is provided: an ectoparasiticidal composition comprising: a polysiloxane at 75 to 90% w / v and selected form any one of dimethiconol, dimethicone or phenyl dimethicone; a first ester at 10 to 18% w / v and selected form any one or a combination of diisopropyl adipate, neopentyl glycol diethylhexanoate or diisostearyl malate; a second ester different to the first ester at 2 to 8% w / v and selected form any one or a combination of diisopropyl sebacate, neopentyl glycol diethylhexanoate or diisostearyl malate; an antioxidant at 0.0001 to 0.1% w / v and selected form any one of tocopheryl acetate or tocopheryl; and a Ce-Ci6 aliphatic alcohol at 0.4 to 2.0% w / v and selected form any one or a combination of a Cs-Ci6 aliphatic alcohol, a Cs-Ci4 aliphatic alcohol or a Cio-Cm aliphatic alcohol. Optionally, the polysiloxane is included at 76 to 88 % w / v or 78 to 86% w / v. Optionally, the polysiloxane comprises a kinematic viscosity in the range 10 to 200 mm2 / s, 30 to 150 mm2 / s, 40 to 120 mm2 / s or 40 to 80 mm2 / s. Kinematic viscosity as referred to here may be determined by ASTM D445 being the standard test method to measure the kinematic viscosity. As will be appreciated, the method involves measurement of the time for a fixed volume of liquid to flow under gravity through the capillary of a calibrated viscometer under a reproducible driving head and at a closely controlled and known temperature. The kinematic viscosity (determined value) is the product of the measured flow time and the calibration constant of the viscometer. Two such determinations are needed from which to calculate a kinematic viscosity result that is the average of two acceptable deter- mined values. Temperature control for each series of flow time measurements, the temperature control of the bath liquid shall be such that within the range from 15 to 100°C, the temperature of the bath medium does not vary by more than +0.02°C of the selected temperature over the length of the viscometer, or between the position of each viscometer, or at the location of the thermometer. For temperatures outside this range, the deviation from the desired temperature must not exceed 0.05°C. Optionally, the polysiloxane comprises any one or a combination of: a linear polysiloxane; a branched polysiloxane; a cyclic polysiloxane; and a silicone copolymer. Optionally the first ester comprises any one or a combination of: a diester; an adipate ester; and a malate ester. The first ester is particularly effective as a lubricant whilst being fully compatible with the siloxane, antioxidant and alcohol. Optionally, the second ester comprises any one or a combination of: a sebacate; a diester; and a malate ester. The second ester is particularly effective as a lubricant whilst being fully compatible with the siloxane, antioxidant and alcohol. Optionally, the antioxidant comprises any one or a combination of: a vitamin E compound; a vitamin E derivative; and vitamin E acetate. Optionally, the antioxidant comprises: tocopherol acetate; or tocopherol. Optionally, the aliphatic alcohol comprises any one or a combination of: 1-deconol; 1-tetradeconol; and dodecanol. The aliphatic alcohol having the recited carbon chain length has been identified to be effective as an emulsifying agent and to function synergistically with the lubricant and antioxidant in wetting the skin / scalp and hair for the effective delivery of the active ingredient to all surfaces / regions of infestation. The present formulation via the identified and recited aliphatic alcohol also provides for the homogeneity and uniform / dispersed delivery of the poly siloxane to all surfaces of the skin and hair. The present composition via the choice of ingredients including in particular the aliphatic alcohol is suitable to be delivered as a spray including both pump and aerosol delivery mechanisms for the uniform dispersed delivery of the active agent to the treatment region. Optionally, the composition comprises water up to 100% w / v of the composition. That is all %wt expressed herein are the weight (gram) amounts of compounds added to a 100ml base solvent / liquid. Optionally, the polysiloxane is dimethicone at 79 to 85% w / v; the first ester is diisopropyl sebacate, neopentyl glycol di ethylhexanoate or diisostearyl malate at 13 to 15% w / v; the second ester is diisopropyl sebacate, neopentyl glycol diethylhexanoate or diisostearyl malate at 4 to 5% w / v; the antioxidant is tocopherol acetate at 0.007 to 0.01% w / v; and the Ce-Ci6 aliphatic alcohol is 1-deconol, 1-tetradeconol or dodecanol at 0.4 to 2.0% w / v. In some aspects, the present composition is suitable for use in the treatment of infestation in humans by parasites from the families Pediculidae and Pthiridae. Detailed description of preferred embodiment of the invention The following examples illustrate aspects of the present concept in more detail. Compositions according to the present concept are detailed in the following table 1: Ingredient Exp 1 Exp 2 Exp 3 Exp 4 Exp 5 Exp 6 Dimeticone 80 - - 79 81 84 Phenyl dimeticone - 82 - - - - Dimeticonol - - 80 - - - Diisopropyl Adipate 14 - - 13.5 - 14.2 Neopentile Glycol Diethylhexanoate - 15 13 - 14 - Diisostearyl Malate - 5 4 - - - Diisopropyl Sebacate 4.5 - - 4 4.5 5 Tocopheryl Acetate 0.008 - 0.007 0.008 0.008 0.007 Tocopheryl - 0.01 - - - - 1-decanol - - 0.9 0.85 - - 1-tetradeconol - 1.2 - - - 1.3 dodecanol 1.1 - - - 1.0 - Table 1 - concentrations of example compositions according to the present concept. All amount indicated are % w / v and are expressed as gram (g) added per 100ml of base liquid. 5 Reference within the specification to a concentration is expressed as % weight / volume of the composition. Such definition is the mass concentration of solution as percent weight per volume with a total volume is 100 ml. Accordingly, under such a definition, one g of compound x within 100 ml provides a 1% w / v solution of compound A. 10 Composition Preparation Example 1 100 ml water was added to a suitable preparation vessel. The following compounds were 15 weighed and then added individually to the 100ml water with 5 to 15 minutes stirring per addition. Additional stirring of 10 minutes was repeated where necessary if the additives where not fully mixed / solvated: 80g Dimeticone; 14 g Diisopropyl Adipate; 4.5g Diisopropyl Sebacate; 0.008g Tocopherol Acetate and 1.1g dodecanol. The solution was heated at 30°C until a colourless, clear (fully transparent) liquid solution was obtained. The solution was stirred for a further 20 minutes using a mechanical mixer if necessary to achieve the clear colourless solution. 5 Examples 2 to 6 The same preparation process of Example 1 was repeated for each of the examples 2 to 6 (Table l)having each of the five ingredients at their respective concentrations (wt gram amounts) involving sequential addition to 100 ml water with stirring and mild heating to 10 obtain the clear colourless liquid solution.

Claims

1. An ectoparasiticidal composition comprising:a poly siloxane at 75 to 90% w / v and selected form any one of dimethiconol, dimethicone or phenyl dimethicone;a first ester at 10 to 18% w / v and selected form any one or a combination of diisopropyl adipate, neopentyl glycol diethylhexanoate or diisostearyl malate;a second ester different to the first ester at 2 to 8% w / v and selected form any one or a combination of diisopropyl sebacate, neopentyl glycol diethylhexanoate or diisostearyl malate;an antioxidant at 0.0001 to 0.1% w / v and selected form any one of tocopheryl acetate or tocopheryl; anda Ce-Ci6 aliphatic alcohol at 0.4 to 2.0% w / v and selected form any one or a combination of a Cs-Ci6 aliphatic alcohol, a Cs-Cm aliphatic alcohol or a Cio-Cm aliphatic alcohol.

2. The composition as claimed in claim 1 wherein the polysiloxane is included at 76 to 88 % w / v or 78 to 86% w / v.

3. The composition as claimed in claim 1 or 2 wherein the polysiloxane comprises a kinematic viscosity in the range 10 to 200 mm2 / s, 30 to 150 mm2 / s, 40 to 120 mm2 / s or 40 to 80 mm2 / s.

4. The composition as claimed in claim 1 wherein the aliphatic alcohol comprises any one or a combination of:• 1-deconol;• 1-tetradeconol; and• dodecanol.

5. The composition as claimed in any preceding claim comprising water up to 100% w / v of the composition.

6. The composition as claimed in claim 1 wherein:the polysiloxane is dimethicone at 79 to 85% w / v;the first ester is diisopropyl sebacate, neopentyl glycol diethylhexanoate or diisostearyl malate at 13 to 15% w / v;5 the second ester is diisopropyl sebacate, neopentyl glycol diethylhexanoate ordiisostearyl malate at 4 to 5% w / v;the antioxidant is tocopheryl acetate at 0.007 to 0.01% w / v; andthe Ce-Ci6 aliphatic alcohol is 1-deconol, 1-tetradeconol or dodecanol at 0.4 to2.0% w / v.