This invention relates to a method and com¬ position for eradicating lice infestations.

Lice have constituted a "plague" on mankind for many centuries. There are essentially three main types of infestation by lice specific for the human host: 1 Pedi¬ culosis Capitis 2. Pediculosis Corporis and 3. Pediculosis Pubis. Head and body infestations are caused by two dif¬ ferent types of Pediculosis hu anus. Public infestations are caused by Phthirus pubis. As the lice feed on human skin, they inject their digestive juices and fecal material into the skin. These materials, as well as the puncture wound itself, cause pruritus. The adult female louse has a lifespan of about one month and lays up to ten eggs a day which are firmly attached to hair. These hatch in about seven to nine days and become mature in another week.

Currently utilized therapies for pediculosis all involve ap¬ plication of toxic pesticides to the scalp or body. Agents such as lindane and DDT form the first line of therapy for pediculosis. These agents are potent neuro- toxins, as well as carcinogens, and are thus far from de¬ sirable agents.

The object of the present invention is to provide an improved method and composition for eradicating lice in¬ festations pediculosis capitis, pediculosis corporis and pediculosis pubis whether the lice infestation is caused by pediculosis humanus or phthirus pubis.

Accordingly, the present invention provides a method of eradicating lice infestations comprising topically

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applying to the lice-infected area an effective amount of one or more of the antipediculocide agents selected from the class consisting of the acid salts of demecarium, echothiopate, edrophonium, neostigmine, pyridostigmine and ambenonium, and isoflurophate, and combinations thereof for a time sufficient to interrupt the breeding cycle of the lice.

The present invention also provides a com¬ position for eradicating lice infestations comprising a carrier having one or more of the antipediculocide agents selected from the class consisting of the acid salts of demecarium, echothiopate and neostigmine, and isofluorophate, said antipediculocide agent being present in an amount not less than about 0.01 percent by weight of the carrier.

I have investigated the effects of topically ap- plied formulations containing demecarium bromide, echo- thiophate iodide, isoflurophate, neostigmine bromide, neo¬ stigmine methylsulfate, edrophonium chloride, pyridostig¬ mine bromide and ambenonium chloride on human louse in¬ fections by having patients affected with such infestations - apply some of these compositions. Additionally, other of these topical formulations were evaluated by exposing live nits to these products, and counting the number of lice which hatched from the nits over the next 14 days.

In the practice of this invention, concentrations of demecarium bromide, echothiophate iodide, isoflurophate, edrophonium chloride, neostigmine bromide, neostigmine methyl¬ sulfate, pyridostigmine bromide, and ambenonium chloride ranging from 0.01% to 5.0% were incorporated into creams, lotions, solutions and shampoos and applied to the hair of subjects afflicted with lice infestations or applied to isolated nits on hairs in vitro.

In general, the acid salts of demecarium, echo¬ thiophate, edrophonium, neostigmine, pyridostigmine and am¬ benonium as well as isoflurophate are useful in the practice of this invention. .The carrier can be any pharmaceutically

acceptable agent which is suitable for topical application to the skin and may include emollients, emulsifiers, stabilizers, softeners, perfume, coloring agents, and the like. If the antipediculocide effective ingredient is present in an amount of less than about 0.01% by weight of the carrier, the reproductive cycle may not be in¬ terrupted, whereas if the effective ingredient is present in an amount substantially greater than 5% by weight of the carrier then at least for isoflurophate human toxicity may be a problem, the preferred range being from about 0.1 to about 5% by weight of the carrier.

In every case the antipediculocide ingredient must remain in contact with the nits for a short time with at least three or five minutes being preferred in order to obtain superior results. Leaving the antipediculous-agen-t¬ in contact with the affected area for three to five minutes results in a cure with only a single application, which is a significant advantage over the soaps and shampoos now available which require repeated treatments. Further, the subject process and composition has the added significant feature of not exposing the patient to the toxic effects of DDT or lindane.

EXAMPLE 1

A topical antipediculocide prepared by incor- porating 0.125% demecarium bromide into a lotion (con¬ taining water, mineral oil, petrolatum, sorbitol, lanolin, lanolin alcohol, stearic acid, triethanolamine, cetyl al¬ cohol, fragrance, butylparaben, methylparaben, propyl- paraben and sodium chloride) was applied to the pubic hair of a 39 year old male afflicted with pediculosis pubis. The lotion was removed by showering 8 hours after ap¬ plication. No evidence of reinfection was later noted.

EXAMPLE 2

Echothiophate iodide 2% was incorporated into a commercially available shampoo. A 12 year old male with pediculosis capitis utilized this shampoo to wash his hair, leaving the shampoo on the. hair for 10 minutes before rinsing. One treatment was sufficient for elimination of the infestation.

EXAMPLE 3

Isoflurophate 0.025% was incorporated into the same lotion vehicle in Example 1, and 5 nits obtained from the hair of a louse infected individual exposed to this lotion in a petri dish. During 14 days of observation after such treatment no lice hatched from the nits.

EXAMPLE 4

Neostigmine ethylsulfate 0.05% was incorporated into the same lotion vehicle as described in Example 1, and 5 nits obtained from the hair of a louse infected in¬ dividual exposed to this lotion in a petri dish. During 14 days of observation after such treatment no lice hatched from the nits.

EXAMPLE 5

Pyridostigmine bromide 5.0% was incorporated into a commercially available shampoo. A 8 year old female with pediculosis capitis utilized this shampoo to wash her hair, leaving the shampoo on the hair for 5 minutes before rinsing.

One week later the treatment regimen was repeated. No evi-

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dence of reinfestation was noted.

EXAMPLE 6

Neostigmine bromide 0.5% was incorporated into the same lotion vehicle as described in Example 1, and 5 nits obtained from the hair of a louse infected individual ex¬ posed to this lotion in a petri dish. During 14 days of observation after such treatment no lice hatched from the nits.

The preferred compounds for use as in anti- pediculocide are the acids salts of demecarium echothio¬ pate and neostigmine well as isofluorphate, with the last named compound being least desirable due to its toxicity.

From the foregoing, it has been shown that pedi¬ culosis capitis, pediculosis corporis and pediculosis pubis whether caused by pediculosis humanus or phthirus pubis have been effectively treated by the method and compo¬ sition disclosed herein, and while there has been disclosed what at present is considered to be the preferred embodiments of the present invention, it will be understood that those skilled in the art that various modifications and altera¬ tions may be made therein without departing from the true spirit of the present invention.

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