GB2357972A

GB2357972A - Optionally substituted siloxane containing liquid composition for the eradication of head lice

Info

Publication number: GB2357972A
Application number: GB0004445A
Authority: GB
Inventors: Jane Ansell
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-09-16
Filing date: 2000-02-24
Publication date: 2001-07-11
Also published as: GB9921858D0; GB0004445D0

Abstract

A fluid composition for the eradication of head lice comprises an insecticide, characterised in that the composition includes at least one substituted or unsubstituted diloxane as the insecticide. The siloxane may be a linear compound, a cyclic compound or a block copolymer. If the cyclic siloxane is substituted it may have four to six siloxy residues in the ring but if it is unsubstituted it may have at least five siloxy residues in the ring. The siloxanes may be a mixture of linear siloxanes and cyclosiloxanes. Preferably the fluid composition also contains dissolved or dispersed dimethiconal (present from 0.1 to 15 percent by volume). The fluid may also contain less that three percent by weight of an analgesic(eg camomile essence), an antiseptic (eg lavender oil), an anti-inflammatory and/or a repellent (eg feverfew essence) composition; preferably the amount is less than one percent by weight. The fluid may contain at least one oil selected from the group containing cedarwood oil, clove oil, geranium oil, lavender oil, lemon oil, eucalyptus oil and rosemary oil. The fluid may comprise from 85 to 99.9 percent by volume of the substituted or unsubstituted cyclosiloxanes. Preferably the fluid comprises 95.5 to 97.5 percent by volume cyclopenta-siloxane and 2.5 to 4.5 percent by volume dimethiconal. The compositions may also be used to eradicate other insects, including arachnids (such as mites).

Description

2357972 COMPOSITION AND METHOD FOR THE ERADICATION OF HEAD LICE This

invention relates to a novel composition for the eradication of head lice and to a method by which it may be 5 used.

Head lice frequently infest human hair and are easily spread by contact. Such infestations are particularly prevalent among children of school age and in the associated institutional environment can spread rapidly. The louse itself is mobile and the female of the species can lay many hundreds of eggs in its lifetime. Transfer of the mature lice leads to the spread of infestation while the adhesion of eggs to hair ensures a reservoir of lice in each invested head. The eggs are commonly referred to as 1InitsIT.

Eradication of head lice involves total removal or destruction of both the mature lice and the eggs on each host. Various attempts have been proposed to achieve such destruction but none are wholly satisfactory.

The eggs and mature lice may be removed by combing the hair with a special comb having very fine gaps between the teeth. Such combing removes all mature lice easily and destroys the bond between the eggs and the hair so that the combing action releases the eggs or catastrophically ruptures them. For the host subject regular combing with a "nit comb" is a painful and undignified procedure.

In an alternative procedure the hair is treated with an insecticidal spray or washed with an insecticidal shampoo. One approved and widely used insecticide for this purpose is malathion, an organo -phosphorus compound. This compound has an unpleasant odour and causes allergic reactions in some subjects. Insecticides are not entirely effective so that reinfestation can occur. Organic insecticides such as hexachlorocyclohexane, malathion and pyrethrins can cause toxic responses in humans such as nerve damage. Such responses are considerably more dangerous than the headlice infestations which they are used to treat. Furthermore headlice can mutate and develop resistance to insecticides of this nature.

It has been proposed that vegetable oils, such as olive oil, should be used to treat headlice infestations by causing suffocation. Such treatment has the disadvantage that application of the oil is unpleasant both for the person applying the oil and the person to whom it is applied. Removal of the oil from treated hair requires the use of strong detergents which tend to damage the hair cuticle and destroy the hair's natural protection from head lice infestation.

The present invention provides a composition that eradicates head lice without causing allergic reactions and acting in a manner that inhibits re-infestation.

According to the present invention there is provided a fluid composition for the eradication of head lice comprising an insecticide, characterised in that the composition includes a substituted or unsubstituted siloxane as the insecticide.

In a preferred embodiment the fluid composition also contains dissolved or dispersed dimethiconal.

The composition is massaged into the hair and scalp of patients infested or believed to be infested with head lice. The insecticide action of the silicone compounds kills or incapacitates the lice. After treatment the hair may be washed with a mild shampoo to remove the dead lice and detached eggs. The silicon residue, retained within the cuticles of the hair, acts as a lubricant allowing any eggs (nits) to be combed out of the hair and preventing any subsequently laid eggs forming an adhesive bond with the hair. The eggs are eliminated when the hair is washed or combed. A full head treatment should be repeated after ten days to destroy any lice emerging after the first application. Subsequent daily applications of a few drops rubbed between the palms and dispersed through the hair, above the ears and above the nape of the neck ensures freedom from further infestation. Such regular treatment with the fluid will ensure that reinfestation does not occur due to contact with lice carriers.

The siloxane may be a linear compound having the formula CH3 CH3 CH3 H3C-S'-0- -SI-0- -Si-CH3 1 1 1 CH3 R j n CH 3 where n may lie in the range 0 to 10 and R is a substituent such as a phenyl group, an alkyl group having up to 16 carbon atoms, a polyoxyethylene group. Block copolymers of the of such linear compounds may also be used. Such compounds are commercially available from Dow- Corning under the proprietory designation numers 190; 193; 200; 556; 2502 and 5324.

The silaxane may have a cyclic siloxane ring. The substituted cyclosiloxanes preferably have four to six siloxy residues in the ring while unsubstituted cyclo- siloxanes should have at least five siloxy residues. Mixtures of linear siloxanes, of cyclosiloxanes or of both linear and cyclo compounds may be used and are preferred. Blends of methyl substituted 3, 4 and 5 siloxy ring polymers are available under the name cyclomethicone. Such blends are non- toxic and compatible with a wide range of other fluids such as solvents. Cyclosiloxanes are volatile and will be lost from the hair by evaporation after treatment. Cyclomethicone is available as Dow Corning345 Fluid. Dimethiconal admixed with unsubstituted cyclopentasiloxane is available as Dow CorningZ1501. Dimethiconal has a low volatility and provides a long lasting silcon compound residue in the hair.

is In use preferred compositiQne comprise a mixture of J5_) Dow Corning1501 and Dow CorningX345 in a ratio by volume of one part 1501 to three to four parts 345. If the amount of 345 is increased beyond four parts the low siloxane viscosity of the fluid causes it to run out of the hair and on to the face and neck of the person being treated. This problem may be overcome by creating a thixotropic mixture by the addition of a thickener. Fluids having less than three parts 345 tend to have too high a viscosity for convenient application. The viscosity may be lowered by the addition of a supplementary solvent.

The basic fluid insecticide composition may include one or more additives to improve its acceptance by sensitive patients. These additives comprise analgesics, antiseptics, anti- inf lammatories and repellents. Such additives form a minor proportion of the composition, usually less than one percent, but in certain cases may be present up to 3 percent.

Repellents include an oil containing essence of feverfew alone, in combination or substituted by other oils such as cedarwood, clove, geranium, lavender, lemon or rosemary. 5 The substituted or unsubstituted cyclosiloxane is preferably present in the fluid composition from 85 to 99.9 percent by volume. Dimethiconal may be present from 0.1 to 15 percent by volume. A most preferred range of constituents consists of 97.5 to 95.5 percent cyclopentasiloxane and 2.5 to 4.5 percent dimethiconal. This mixture may further contain up to one percent eucalyptus oil.

is To reduce irritation of the scalp which may occur in a small minority of patients camomile essence may be added as an analgesic. It may be used alone, in combination or substituted by lavender or peppermint oils.

To prevent scalp infection if the skin is sensitive or has become abraded lavender oil is the preferred anti septic. It may be used alone, in combination or substituted by essential oils from cedarwood, cinnamon, juniper, lemon, lemon grass, myrrh, neroli, peppermint, opine, rose, sage, sandalwood or tea tree.

It will be understood that certain of the essential oils can act in more than one way, for example feverfew can act both as a repellent and as an anti-inflammatory compound. Similarly myrrh can act both as an antiseptic and as an anti- inflammatory compound.

As is well known, products extracted from plants can vary in exact composition and effectiveness according to the growing conditions and location. Further variations 6 - can occur through inconsistencies in extraction and concentration processes. For this reason the amount of such compounds added to the composition must be decided following testing of each batch of extract.

The additives used in the composition are subject to change through the effects of sunlight, head and other storage conditions. To reduce such changes known preservative compounds, such as anti-oxidants and ultra-violet radiation absorbing compounds may be included.

The action of the cyclosiloxanes in the composition may be enhanced in some cases by the addition or small amounts of hydrocarbon oils or waxes or a dispersion of polytetrafluroethylene particles.

Further compounds may be added to the fluid composition of the invention so that it has detergent properties and may act as a shampoo while at the same time retaining its insecticidal properties. Such compositions perform the dual functions of cleaning hair and both removing any headlice lice and nits present and providing residual protection against reinfestation.

The mode of action of the composition is believed to involve suppression of oxygen intake by headlice and their eggs causing suffocation. Such action does not involve toxic action within the operation of the life support system of the insects and there is a low probability of resistance being created through genetic mutation. It is also believed that the effect can be obtained on other life forms, such as other insects including lice, and especially arachnids enabling the fluid composition of the invention to be used on arachnids such as mites and the infestations produced by such creatures.

7

Claims

1. A fluid composition for the eradication of head lice comprising an insecticide, characterised in that the 5 composition includes at least one substituted or unsubstituted siloxane as the insecticide.

2. The fluid composition as claimed in claim 1, characterised in that the fluid composition also contains dissolved or dispersed dimethiconal.

3. The fluid composition as claimed in claim 2, characterised in that at least one siloxane is a linear compound having the formula CH3 CH3 CH3 1 1 1 H3C-Si-0- --Si-0- CH3 L R j CH 3 2 0 where n may lie in the range 0 to 10 and R is a substituent such as a phenyl group, an alkyl group having up to 16 carbon atoms, a polyoxyethylene group.

4. The fluid composition as claimed in claim 3, characterised in that the linear compounds are in the form of block copolymers.

5. The fluid composition as claimed in claim 2, charact30 erised in that the siloxane comprises a substituted or unsubstituted cyclic siloxane.

6. The fluid composition as claimed in claim 5, characterised in that the cyclic siloxane is substituted and has 35 four to six siloxy residues in the ring.

7. The fluid composition as claimed in claim 5, characterised in that the cyclic siloxane is unsubstituted and has at least five siloxy residues in the ring.

8. The fluid composition as claimed in any of the preceding claims, characterised in that it comprises mixtures of linear siloxanes and cyclosiloxanes.

9. The fluid composition as claimed in any of the preceding claims, characterised in that the fluid also contains an analgesic, an antiseptic, an anti- inflammatory and/or a repellent composition.

10. The fluid composition as claimed in any of the preceding claims, characterised in that the additives form less than three percent by weight of the composition.

11. The fluid composition as claimed in claim 10, characterised in that it comprises less than one percent by weight of the composition.

12. The fluid composition as claimed in any of the claims 9 to 11, characterised in that it contains at least one oil selected from the group containing cedarwood oil, clove oil, geranium oil, lavender oil, lemon oil, eucalyptus oil and rosemary oil.

13. The fluid composition as claimed in any of the claims 9 to 12, characterised in that it contains camomile essence an analgesic optionally in combination with lavender or peppermint oil.

14. The fluid composition as claimed in any of the preceding claims, characterised in that it comprises from 85 to 99.9 percent by volume of the substituted or unsubstituted cyclosiloxanes.

15. The f luid composition as claimed in claim 14, charact erised in that dimethiconal is present from 0.1 to 15 percent by volume.

16. The fluid composition as claimed in claim 15, characterised in that it comprises 97.5 to 95.5 percent by volume cyclopentasiloxane and 2.5 to 4.5 percent by volume dimethiconal.

17. Fluid compositions as claimed in claim 1 and as herein described.