Louse Repellent

The present invention relates to pediculicidal compositions and includes a method of controlling louse infestations.

Head lice are a common health problem and spread rapidly in institutions such as the Armed Services and in schools. One of the difficulties in controlling head lice is that the eggs attach themselves very firmly to the base of hairs by adhesive secretions which makes them difficult to remove. Second, the eggs are protected by a waxy cuticle which is not penetrated by currently available anti-louse preparations. Conventional methods of controlling head lice therefore depend on the use of a medicated shampoo or lotion which loosens the natural adhesive or gum which binds the eggs to the hair of the scalp and at the same time is toxic to the hatched and active lice.

Although many of these conventional preparations are satisfactory in some cases if used conscientiously, their success does depend on very thorough repetitive treatments over a long period, They also have the disadvantage that many of the louse repellants which are used have unpleasant smells and this discourages their proper and continuous use over the required period of treatment,

We have now discovered that a compound which is related to benzaldehyde is very effective as a louse repellant.

In its broadest aspect the invention provides a pediculicidal and lice repellent composition which is effective against adult lice and lice eggs which comprises a solution of piperonal, said solution containing a component which maintains the piperonal in solution in contact with the host for at least 2 hours.

Piperonal is an aromatic aldehyde, and has the formula: ##STR1## and its preparation is given in U.S. Pat. No. 2,916,499 and J. Org. Chem. 26, 4814 (1961).

In the past, piperonal has been used quite widely as a constituent of perfumes and flavours, at relatively low concentrations, e.g. 50 ppm, giving a sweet floral tone to fragrances.

Piperonal is soluble in alcohols, glycols and some oils.

In the practice of the present invention, it is fairly important that the piperonal is maintained in solution since it is not as effective in its solid state. Although piperonal is soluble in lower alcohols, e.g. ethanol or isopropanol, the alcohol tends to separate leaving crystalline piperonal deposited on the body or hairs of the host. It has been found that a long-lasting repellent action is achieved by incorporating a hydrophilic film-forming component with the composition. Although not fully established, it is believed that the hydrophilic film-forming component reduces the rate of evaporation of the solvent, thus preventing crystallisation. Whatever the precise mechanism of this advantageous effect, formulations which contain the film-forming component have been shown to exhibit a strong repellent effect towards lice which lasts for up to 6 to 8 hours after the application to the hair.

Solutions of piperonal containing 1% of the active ingredient are generally not very active. A concentration of at least 3% by weight is generally desirable and we prefer compositions containing at least 4% by weight of piperonal. There is no critical upper limit but there is usually no advantage in using more than 10% by weight.

According to the preferred form of the invention there is provided a pediculicidal and lice repellent composition for controlling head lice which comprises a solution of 4 to 10% by weight of piperonal and a film-forming component which is substantive to the hair of the host and is capable of maintaining the piperonal in solution in contact with the hair of a host for at least 2 hours.

Preferably, the film-forming component is a hydrophilic polymer and is preferably present in an Mount of from 0.3 to 3% by weight. Examples of preferred film-forming components are a vinyl pyrrolidone polymer, a vinyl acetate polymer, a quarternized collagen, a quarternized cellulose derivative or a polymer containing hydroxy and amino groups.

As indicated above, piperonal is soluble in alcohols, glycols and some oils, particularly terpene oils. Ethanol or propanol is conveniently used as the main solvent. However, in order to reduce its rate of evaporation, higher alcohols, glycols, compatible oils and/or water may be included in the formulation. For example, the solvent may comprise 50 to 70% ethanol or propanol. Terpenes are a preferred optional ingredient, particularly if maximum ovicidal properties are desired. It is a property of terpenes that they enhance the penetration by the piperonal of the waxy cuticle of the lice eggs. Another desirable optional component is an aliphatic long chain hydrocarbon, which appears to enhance the wetting of the skin of the lice with the pediculicidal compositions.

The following Examples in which all percentages are by weight give illustrative louse repellent compositions in accordance with the invention.

The ingredients specified in the following Examples were mixed in the amounts stated to give the corresponding formulations.

Shellsol T is a complex mixture of long chain alkanes. Terpineol and d-Limonene are naturally occurring terpenes with fairly high boiling points.

Thyme oil is a volatile oil distilled from THYMUS VULGARIS comprises mainly of Thymols and carvacrol. It isa counter-irritant.

Cartaretin F is an Adipic acid/Dimethylamino hydroxy propyl diethylene triamine copolymer. It is a hair fixative.

Soluble lanolin is a modified lanolin. Lanolin is a complex natural wax comprising of esters and polyesters of long chain fatty acids and fatty alcohols.

PVP/VA is a polyvinyl pyrrolidone/vinyl acetate copolymer resin. It is a water soluble film former.

PVP is a polyvinyl pyrrolidone polymeric resin. It is a water soluble film former.

Quarternized Collagen protein is a quarternary derivative of hydrolysed collagen protein. It is a water soluble, highly substantive conditioner.

Quarternized cellulose derivatives are produced by quarternization of hydroalkyl celluloses with a range of alkyl groups. They are conditioning aids.

Other compounds may be included in the compositions of this invention which are pediculicidal, e.g. malathion or carbaryl sevin, although this is not essential.

In the treatment of head lice the piperonal containing formulation is applied to the hair and left in contact for periods between two to twelve hours. Other additives may be included in the preparation, e.g. surfactants to increase the wetting of the hair and ingredients to depress the rate of evaporation of the solution.

The compositions of the present invention have several advantages over conventional anti-louse compositions. In particular, they exhibit superior repellent activity against adult lice. Moreover, because piperonal has a pleasant smell and is approved by government licensing authorities as a food additive, there is no danger of any health risk in using the compositions nor any antipathy among infected persons against acceptance of treatment.

While the invention has been described with particular reference to combating head lice infestations, the compositions of the invention are also effective in the same way against other lice, e.g. crab lice, clothing lice and body lice.