Drug – bio-affecting and body treating compositions – Preparations characterized by special physical form – Biocides; animal or insect repellents or attractants
Reexamination Certificate
1998-06-29
2003-07-22
Levy, Neil S. (Department: 1616)
Drug, bio-affecting and body treating compositions
Preparations characterized by special physical form
Biocides; animal or insect repellents or attractants
C424S078020, C424S078070, C424S406000, C424S077000, C424S078310, C424S485000, C514S724000
Reexamination Certificate
active
06596291
ABSTRACT:
TECHNICAL FIELD
This invention relates generally to compositions and methods for topically treating a hair-bearing surface of a warm-blooded animal infested with an ectoparasitic insect.
BACKGROUND OF THE INVENTION
Lice and fleas (collectively referred to herein as “ectoparasites”) infest a wide range of warm-blooded animals, including humans. A louse is a small, flat-bodied, wingless, biting or sucking insect present as an external parasite on hair-bearing surfaces of various animals. The human lice genera include pubic lice (
Pthirus pubis
, or
Phthirus pubis
), body lice (
Pediculus humanus
var.
corporis
), and head lice (
Pediculus humanus
var.
capitis
).
Pubic lice generally are confined to the hairs of the genital region, while body lice may be found on the hair of the axilla, eyebrows, eyelashes, beards, and hairy body surfaces. Both pubic lice and body lice may be acquired from direct contact with another infested person, from wearing contaminated clothing, from contaminated toilet seats and from contaminated bed linen. Body lice typically occur as the result of crowding in unhygienic conditions, while pubic lice are transmitted sexually.
Head lice are small hard-shelled ectoparasites that cling to hairs of the scalp while feeding, mating and laying eggs. The adult female head louse has a lifespan of about one month, and is ready to mate and reproduce within about a week after hatching. Under ideal conditions, a female head louse may produce up to 100 eggs in her lifetime, most commonly on the hair above the ears and the back of the head of human beings, and near the base of hair shafts. The eggs are cemented to the hair with a tenacious proteinaceous substance. Head lice eggs (commonly referred to as “nits”) are protected by a chitinous sheath which surrounds the eggs and are attached to the hair. These eggs hatch in about seven to nine days and become mature in another week. As with pubic and body lice, head lice are also transmitted by personal contact, as well as by common use of brushes, combs or headgear. Poor hygienic and grooming habits are known to contribute significantly to the spread of head lice. Thus, head lice infestations are most serious in areas where the inhabitants have both substandard hygienic facilities and practices.
Lice have plagued mankind for many centuries, and lice infestation can be found throughout documented history. For example, lice have been responsible for the spread of typhus, causing decimation of many armies and navies from the 15
th
through the 18
th
centuries. Even today, lice are still considered as disease vectors and present serious health problems throughout the world. In particular, lice are vectors for staphylococcal skin infections, such as impetigo and furunculosis, and are also the principle method of transmission for typhus, trench fever and relapsing fever.
Head lice, pubic lice and body lice are all capable of infesting humans (referred to as pediculosis), the characteristics of which differ markedly within the species. Head lice infestation is characterized by itching and dermatitis. In long standing or neglected cases, scratching may result in marked inflammation, secondary infection by bacteria may occur, resulting in the formation of pustules, crusts and suppuration, and the hair may become matted and give rise to a disgusting odor. Today, head lice is an epidemic in roughly 2-3% of grade school children in the United States and England. Body lice infestation is characterized by intense itching and, in cases of heavy infestation, by red skin eruptions, mild fever, tiredness, irritability and possibly weakness. Pubic lice infestation is characterized by itching, especially in the genital or crural regions.
In addition to spreading diseases, lice carry a wide variety of bacteria on their exterior surfaces, and their fecal matter transmits disease when it enters the puncture wounds inflicted during feeding. As the lice feed on human skin, they inject their digestive juices into the skin. These materials, as well as the puncture wound itself, cause pruritus, which is painful to the animal host. Therapy that simply kills the louse leaves subcutaneous or intradermal residues that continue to itch for a significant time after the infestation is extinguished. Furthermore, scratching during and after the episode frequently leads to painful excoriation.
Previous methods for treating animals infested with lice have not been entirely satisfactory. In the past, chemical agents, including toxic pesticides or insecticides (termed pediculicides) have been used. Unfortunately, these compounds include potent neurotoxins, as well as carcinogens such as DDT, carbaryl, piperonyl butoxide, the synthetic pyrethrin analog permethrin or cholinesterase inhibitors such as neostigmine or prostigmine. Such pediculicides range from mildly toxic (pyrethrins) to toxic (lindane and malathion). All current methods involve the exposure of the scalp and hair to these agents in shampoos or creams, which are then washed off relatively quickly. Because of increased concern about the overall safety of such chemical agents, the search for new and effective pediculicides has intensified.
In addition to safety concerns regarding the current pediculicides, other problems also exist. One drawback is that chemical agents may not achieve the desired efficacy. For instance, lice have developed a significant degree of resistance to all of the topical pesticides. Natural pyrethrins and synthetic pyrethroids are routinely chosen for use in the treatment of warm-blooded animals infested with lice. Natural pyrethrins have their limitations as poor environmental stability, which is a severe drawback in the treatment of lice. Additionally, natural pyrethrins have low residual action due to this instability. The practical effect is that the use of natural pyrethrins necessitates frequent follow-up treatments. Synthetic pyrethroids are cheaper, more available and more stable than natural pyrethrins, and generally more effective against lice than natural pediculicides.
Not only are current treatments generally losing their ability to kill the adult lice and eggs, the dead nits remain firmly attached to the hairs after treatment. This is unsettling to the patient, as well a significant cosmetic problem. The only current means of removing dead nits is with a fine toothed comb, fingers or forceps. These methods are time consuming and less than certain. Furthermore, if the patient is a child, the child must be nit-free to return to school.
Other forms of treatment are physical in nature and include removal of the hair-infested areas in question, followed by washing with strong soap and optionally one of the pediculicides listed above. Clothing or instruments in contact with the affected body parts should also be decontaminated. These forms of treatment, however, are less than satisfactory.
In addition to lice, fleas constitute another ectoparasite that infests a wide range of animals. More specifically, the flea is an insect of the order Siphonaptera, marked by lateral compression, sucking mouth parts, extraordinary jumping powers, and ectoparasitic adult life in the hair and feathers of warm-blooded animals, including birds and mammals. The flea genera include the human flea (
pulex irritans
), the cat flea (
ctenocephalides felis
) and the dog flea (
ctenocephalides canis
). Using a suctorial proboscis on its head and armed with piercing mandibles, the flea inflicts an irritating and often painful bite to obtain the blood upon which it feeds.
In the case of dogs and cats, for example, male and female fleas mate while still in the animal's coat. When the female flea lays her eggs, the eggs do not adhere to the fur, but fall off and are distributed to the animal's environment. By this mechanism, the total environment of the animal is infested with flea eggs and infestation is greatest in locations where the animal spends most of its time.
Fleas require a blood meal in order to become sexually mature. Once sexually mature, the fleas are able to reproduce.
Levy Neil S.
Seed I.P. Law Group PLLC
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