WO2001032133A2

WO2001032133A2 - Improved nit removal product

Info

Publication number: WO2001032133A2
Application number: PCT/US2000/041866
Authority: WO
Inventors: Sheldon Murphy
Original assignee: Nature Plus Inc.
Priority date: 1999-11-05
Filing date: 2000-11-03
Publication date: 2001-05-10
Also published as: AU2921601A; WO2001032133A3

Abstract

Nit removal formulations having improved nit removal efficacy, and methods for applying the same, comprising a composition effective to facilitate nit removal from hair, and an acidic ingredient effective to achieve a reduced-pH level, wherein the pH of the formulation is below about 4.0, and preferably in the range between about 2.85 and about 3.15.

Description

IMPROVED NIT REMOVAL PRODUCT

Related Applications

This application claims priority back to U.S. Provisional Application No. 60/163,729, filed November 5, 1999, the disclosure of which is herein incorporated by reference in its entirety.

I. Summary of the Disclosure

Numerous formulations have been developed to treat head louse infections. The efficacy of these treatment formulations vary. However, an important characteristic of any such formulation is the ability to facilitate removal of louse eggs. A formulation's failure to effectively facilitate louse egg removal significantly limits the value of the formulation to users.

It has been found according to the present disclosure that the efficacy of nit removal formulations is significantly enhanced by reducing the pH of such formulations as compared to conventional pH levels for such formulations. Improved nit removal efficacy may be achieved by reducing the pH levels of conventional nit removal products from about 4.4 to a pH value of about 4.0 or less. Unexpectedly high efficiency has been demonstrated at pH levels of about 3.15 and less It is contemplated that the pH of such nit removal formulations may be adjusted through the addition of appropriate acidic agents in an amount sufficient to achieve the desired pH level. For example, an inorganic acid, an organic acid, or a combination thereof may be utilized to achieve the desired pH adjustment. Exemplary acids for use according to the present disclosure include phosphoric, acetic and citric acids.

It has been found that improved nit removal efficacy according to the pH reduction of the present disclosure may be achieved with both enzymatic and non- enzymatic nit removal formulations. Comparative data set forth below, in particular, quantitatively demonstrates the improved clinical efficacy of enzymatic nit removal formulations, as reflected in reduced nit removal force for reduced pH enzymatic formulations. Comparable results were found for non-enzymatic nit removal formulations, for reasons discussed herein. It has been further determined according to the present disclosure that the efficacy of nit removal formulations may be further enhanced by maintaining such formulations in contact with the louse-infected hair for extended periods. For example, it has been found that enzymatic nit removal formulations having a reduced pH, e.g., a pH of less than about 3.15, when allowed to remain in contact with louse-infected hair for periods often (10) minutes or more, exhibit superior nit removal performance as compared to comparable formulations when contacted for conventional contact times of about three (3) minutes. Improved efficacy for extended contact periods was found for non-enzymatic nit removal formulations of reduced pH.

II. Detailed Description

The present disclosure sets forth products and methods that provide significant opportunities to improve nit removal efficacy. In particular, products and methods according to the present disclosure have demonstrated significantly superior performance as compared to prior nit removal formulations, as disclosed for example in U.S. Patent No. 5,547,665, the contents of which are hereby incorporated by reference, or commercially available products such as are available from Care Technologies, Inc. (Darien, CT).

More particularly, the efficacy of each of the formulations disclosed in the '665 patent may be improved through the innovative pH adjustment and/or treatment modalities disclosed herein. Rather than repeating the full disclosure of the '665 patent herein, the present disclosure incorporates by reference such disclosure. It should be understood by a person of ordinary skill in the art that it is contemplated by the inventor of the present disclosure that each and every formulation disclosed in the '665 patent may be improved upon through a pH adjustment and/or treatment modality modification, as described in greater detail hereinbelow.

According to the present disclosure, improved nit removal performance is achieved by reducing the pH of nit removal products to reduced values relative to conventional nit removal formulations. In preferred embodiments of the present disclosure, enzymatic nit removal formulations exhibit significantly improved performance through pH reductions to values of about 3.15 or less. Non- enzymatic nit removal formulations also exhibit improved efficacy based upon a pH reduction, as described hereinin particular wherein the pH is reduced to a value of about 4.0 or less. Such pH adjustment may be achieved through nit removal formulations that include appropriate acidic ingredients, e.g., an inorganic acid, an organic acid, or a combination thereof. Exemplary acids for use according to the present disclosure include phosphoric, acetic and citric acids.

It is believed that the improved performance of nit removal products formulated according to the present disclosure may be attributable, at least in part, to a reduced level of hair swell associated with formulations having an appropriately lowered pH value. In particular, it has been found that enzymatic formulations, wherein the pH is lowered through acid addition to a level of less than or equal to 3.15, cause measurably reduced hair swell when brought into contact for various periods of time, e.g., three (3) to ten (10) minutes. It has further been found that the force to remove hair lice and/or nits from hair tresses is significantly reduced when the level of hair swell is minimized. This observation appears logical because, as a hair swells, e.g., during conventional nit removal formulation treatment, the nit sheath would necessarily tighten its grip on the hair. Conversely, to the degree hair swell is kept to a minimum, it is logical to expect that the force to remove the lice/nit from the hair should be minimized.

Based on testing performed on enzymatic nit removal products, it has been found that (i) enzymatic nit removal products having a pH of about 3.15 or less cause significantly lower hair swell than conventional enzymatic nit removal products that have pH values of 3.99 to 4.59, (ii) the reduction in hair swell associated with use of enzymatic nit removal formulations having a reduced pH, as described herein, translates to a measurable reduction in the force required to separate lice and/or nits from a hair tress, and (iii) the reduction in force achieved through the use of enzymatic nit removal formulations having a reduced pH, as described herein, further translates into improved efficacy for such enzymatic nit removal products.

In addition, it has been determined according to the present disclosure that increased contact time for nit removal products, and particularly enzymatic nit removal products of reduced pH, as described herein, improves the efficacy of such nit removal products. Conventional enzymatic nit removal products recommend that the nit removal product be maintained in contact with the hair for

j - about three (3) minutes, before it is rinsed. However, according to the present disclosure, contact times of up to about ten (10) minutes have been found to enhance the effectiveness of the formulation in effecting lice/nit removal. Greater contact periods may further improve nit removal efficacy, although such extended contact may cause skin irritation issues that may clinically counterbalance such improved efficacy. As noted above, conventional enzymatic nit removal products, which have pH values of about 4.4 to 3.99, cause significantly greater hair swell than enzymatic nit removal products having reduced pH values, e.g., pH levels of about 3.15 or less. Based on the correlation between hair swell and pH, it is thought that superior performance with increased contact time may be achieved because the increased contact time does not cause incremental deleterious hair swell, but rather allows an advantageous extension of the time for the nit removal product, whether enzymatic or non-enzymatic, to effect a weakening of the hold of the lice/nit on the hair tress.

Formulations

The following exemplary formulations have been developed according to the present disclosure, each of which exhibits superior nit removal properties as compared to conventional nit removal products. The present disclosure is not limited to these formulations, however. Rather, it is believed that the efficacy of any enzymatic or non-enzymatic nit removal product may be improved through foπnulative steps to reduce the pH to a level of less than about 4.0, and preferably pH levels of about 3.15 or less.

Name: C2 (pH-reduced)

Quality Control Results: pH = 2.98 specific gravity = 1.004 clarity: clear color: water white

Name: C3 (pH-reduced)

Quality Control Results:

• pH = 2.9

• clarity: clear

• color: pale yellow

Name: C4 (pH-reduced)

Quality Control Results:

• pH = 2.98

• clarity: clear

• color: pale yellow Name: C5X (pH-reduced)

Quality Control Results: • pH = 3.00

Name: CBX (pH-reduced)

Quality Control Results:

• pH = 3.00

• specific gravity: 1.014

• clarity: clear

• color: pale yellow

Name: NR-H (pH-reduced)

Quality Control Results:

• pH = 2.9

• clarity: clear

• color: gold

Nit Combs

Nit combs, by definition, must have closely spaced teeth in order to grip the louse eggs tightly enough to remove them from the hairs. Wider spaced teeth will simply not work. Similarly, plastic combs claiming to achieve the removal of nits have generally not performed well because the plastic materials involved are not sufficiently rigid to withstand the forces employed for nit removal. Consequently, metal combs are clearly preferred for optimal nit removal. Metal combs invariably cause some stress and damage to the hair or scalp primarily because they are inflexible and, in combs of lesser quality, actually abrade the hairs. The use of efficacious treatments to facilitate nit removal are thus advantageous in that such use makes the removal process easier for the care- provider and less uncomfortable for the recipient of the treatment.

Conventional Treatment Procedure

Typical lice egg/nit remover application instructions involve the following steps:

1. Wet hair and blot to remove excess water.

2. Apply product generously to target infested area. 3. Massage product into hair.

4. Wait 3-5 minutes for lice egg glue to loosen from hair

5. Use a nit comb thoroughly to remove the loosened eggs and any adults.

6. Rinse hair with water.

Product is safe for repeat applications. The product acts to loosen the lice eggs/nits attached to the hair. Upon proper and thorough combing, the eggs and live adults will be removed. If it is desired to kill the adults and not just remove them, a commercially available lice killing agent should be used before this lice egg/nit remover treatment.

III. Testing

Testing of enzymatic stability at reduced pH

To determine the effect of pH on the stability of enzymes in a variety of nit removal formulations over time, a control non-pH adjusted sample was tested for enzymatic activity, and such result was compared to enzymatic activity for a series of pH-adjusted samples approximately four (4) months post-formulation.

Table 1 sets forth the enzymatic activity for a conventional enzymatic nit removal formulation having a pH of 4.41.

TABLE 1

By contrast, Table 2 shows the reduced enzymatic activity for enzymatic nit removal formulations having a pH of 2.98 to 3.0 about four (4) months post- formulation. Although not reflected in the Table 1, each of the formulations reported in Table 2 exhibit comparable enzymatic activity to that shown for the non pH-adjusted C5X sample. In other words, if tested, each of samples C2, C3, C4, C5, and CBX would, at zero time, exhibit enzymatic activities for alkaline phosphatase, esterase, esterase lipase, acid phosphatase, and NBP. However, as is readily apparent from the data of Table 2, significantly reduced enzymatic activity was demonstrated by the pH-reduced formulations (pH of 2.98 to 3.0, samples tested four (4) months post-formulation, unless otherwise indicated), in that only a single active enzyme was detected for each formulation. More particularly, a comparison of Table 2 with Table 1 shows that four (4) enzymes present in the non-pH adjusted formulation were not detected in the pH-adjusted formulation (after four months), and that the sole enzyme detected in the pH-adjusted formulation (Naphtol-AS-BI Phosphohydrolase) was detected at a significantly reduced activity level.

TABLE 2

Sample was tested one (1) month after formulation. Based on the foregoing data, the majority of detectable enzymatic activity of conventional nit removal products having conventional pH values of about 4.4 is eliminated by pH reductions to values of about 3.0 (over a one to four month period). Indeed, four of the five enzymes initially detected in such conventional nit removal formulations are not detected in the pH-adjusted formulation, and the remaining enzyme (NBP) evidences an activity reduction of approximately fifty percent (50%).

Although not established through conclusive testing, the reduced enzyme activity observed for pH-reduced enzymatic nit removal formulations, over time, may be attributed to (i) the destruction of enzyme molecules and or (ii) a loss of homogeneity in the formulations. A gel-like build-up on the bottom of sample containers has been observed after aging. This settling process may extract enzymes out of solution, and as a result, the material tested from an aged sample bottle may not adequately represent a normal enzyme array. In any case, the lowering of pH has a measurable effect on reducing enzymatic activity. Despite this reduction in detectable enzymatic activity, the lowering of pH has been found to improve formulation efficacy for nit removal to such a degree that superior performance results notwithstanding reduced detectable enzymatic activity.

Louse egg cultivation

Louse eggs were obtained on hairs by providing a culture colony of human clothing lice, Pediculus humanus, with clean, uncolored, unbleached and otherwise untreated human hairs of European origin as a substrate upon which to lay their eggs. One tress of hairs approximately sixty (60) millimeters long was bound at one end using polyvinyl chloride (PVC) adhesive tape and then arranged around the bottom of a crystallizing dish. Freshly fed adult lice were placed on the hairs and permitted to lay eggs over a forty eight (48) hour period. After the lice were removed from the hairs, the eggs and hairs were cooled to prevent emergence of the lice and then stored under ambient conditions at 25° Celsius and 50%) relative humidity until used for testing. A single tress of hair was divided into six (6) parts that were stored separately until use.

Test methodology for Removal Force Measurements

Several glass micropipette tubes (Drummond microcap, 1 microlitre capacity) were each glued across the face of a glass microscope slide using an epoxy resin adhesive. The bore of the microcap was wide enough to permit a single human hair to pass through, but sufficiently narrow to preclude a head louse (or clothing louse) egg or nit from passing therethrough. Any louse egg pulled against the end of the tube was subjected to pressure that causes either the glue to release its grip on the hair or break it away from the hair shaft.

A sleep-peel tester model SP-101 A (Instrumentors Inc., Cleveland, OH) was utilized in accordance with its instruction manual. A clip for attaching a single hair was fixed to the load cell and mount assembly. A single hair, bearing a single louse egg or nit was threaded through the micropipette tube and the glass slide mounted on the platen so that it was fixed. The hair was then inserted into and grasped by the clip on the load cell. When so arranged, the nit was free at the opposite end of the glass tube.

The tester was then started and the platen allowed to move freely on its drive screw until the nit slipped on the hair, having been dislodged as it was pulled against the end of the microcap tube. The tester was then stopped and the peak resistance value (static value) was obtained from the digital display read-out and recorded. The peak resistance value measured the maximum force required to initiate slippage of the nit on the hair.

In performing the tests, twenty (20) hair samples were tested under each treatment regimen. For non-control tests, the hairs were immersed in an excess of the test formulation and massaged to mimic normal use. Exposure to the formulation was for a minimum of three (3) minutes, but the majority of the hairs were exposed to the treatment for a marginally longer period as would also be the case in typical consumer use.

Testing of Nit Removal Forces

Using the methodologies of the type generally described hereinabove, two (2) enzymatic nit formulations were tested at a conventional pH value (about 4.4) and reduced pH levels (about 3.0) to determine average head lice nit (egg) removal forces from human hair. In each instance, a water control was utilized. The results demonstrate significant nit removal force reductions for samples having a reduced pH. Table 3 reflects the nit removal force data for enzymatic nit removal formulations and a control (water), wherein the nit removal formulations had conventional pH levels of about 4.4.

TABLE 3

Based on the foregoing data, the enzymatic nit removal products demonstrate reduced force for removal of nits as compared to a control (water). In particular, the C2 sample required 19% less force than the control, whereas the C5X sample required 3.6% less force than the control.

Table 4 reflects the nit removal force data for enzymatic nit removal formulations and a control (water), wherein the nit removal formulations had reduced pH levels of about 3.0.

TABLE 4

Table 5 shows the percent reduction in force to remove nits for the pH- reduced nit removal formulations as compared to the Control (water), based on the data in Table 4.

TABLE 5

Based on a comparison of the relative performance of the pH-reduced C2 sample, as reflected in Tables 4 and 5, and the non pH-reduced C2 sample, as reflected in Table 3, it is apparent that the pH -reduced C2 sample exhibits improved performance. In particular, the pH-reduced sample exhibited a 21% force reduction (relative to the water control), whereas the conventional C2 sample (having a pH of about 4.4) exhibited a 19% force reduction.

Results of ongoing testing of alternative formulations have demonstrated greater levels of enhanced efficacy according to the present disclosure.

Statistical Analysis of Nit Removal Data

The objective of this analysis was to determine confidence levels at which it can be concluded that treatment with a new formulation NR-H reduces the force required for removal of head lice nits (eggs) from human hair even more than previous formulations. <NEED TO SET FORTH FORMULATION NR-H IN ABOVE FORMULATION SECTION>

Two tests were carried out. Test 1 included force measurements for hair strands treated with the Control (water), and hair strands treated with NR-H. It involved 20 control strands and 38 NR-H strands. Test 2 included force measurements for hair strands treated with the Control (water), and hair strands treated with NR-H. This test involved 30 strands for the control and 30 strands for the NR-H treatment. In both formulations the pH was adjusted to 3.0

The data were analyzed using Analysis of Variance methods. Data were analyzed on the log scale but means and standard deviations were back- transformed to the arithmetic scale.

Tables 6 and 7 give the means and standard errors for the data of Test 1 and 2, respectively.

TABLE 6

Treatme Mea SE nt n

Control 3.92 .71

NR-H 0.77 .18

It can be stated with greater than 99% confidence that formulation NR-H in Test 1 showed reduced force requirements relative to the control.

TABLE 7

Treat Mean SE ment

Contr 4.55 .65 ol

NR-H 1.53 .22 The data confirm that formulation NR-H showed Test 2 reduced force requirements relative to the control (again with greater than 99% confidence). The control means were slightly larger for Test 2, than Test 1 , but not significant.

In contrast to previous formulations C2, C4, C5X, the pull force for nit removal is one-half or less for the NR-H formulation at the same lowered pH.

In a subsequent test, the best formulation NR-H was modified to remove the enzymes, yet the pH was maintained at 3.0. The objective was to see if the common pH of 3.0, of the two formulations (NR-H and NR-H WO 'without enzymes') showed any significant difference between the force to remove the nits. The results are shown on Table 8, which sets forth the means and standard errors for Test 3. On Treatment NR-H, 16 nits were pulled and on NR-H WO, 32 nits were pulled.

TABLE 8

Treatment Mean SE

NR-H 1.80 .33

NR-H 2.14 .27

It can be stated with greater than 95% confidence that formulation NR-H verses NR-H WO show no difference in force required to remove nits from the hair. While the NR-H values are slightly lower, it cannot be concluded that real differences exist with 95% confidence. This experimental data confirms the importance of the pH effect, whether for enzymatic or non-enzymatic formulations.

Claims

IV. Claims

1. A nit removal product, comprising (i) a composition effective to facilitate nit removal from hair, and (ii) an acidic ingredient effective to achieve a reduced pH level.

2. The nit removal product of claim 1 , wherein said reduced pH level is less than about 4.0.

3. The nit removal product of claim 1 , wherein said reduced pH value is less than about 3.15.

4. The nit removal product of claim 1 , wherein said reduced pH value is between about 2.85 and 3.15.

5. The nit removal product of claim 1 , wherein said composition includes at least one enzymatic agent to facilitate nit removal.

6. The nit removal product of claim 5, wherein said at least one enzymatic agent is selected from the group consisting of alkaline phosphatase, esterase, esterase lipase, acid phosphatase, naphtol AS-BI-phosphohydrolase, and combinations thereof.

7. The nit removal product of claim 1, wherein said composition includes substantially no enzymatic agent.

8. A method for removing nits from hair, comprising the steps of:

(i) providing a nit removal product having a pH of about 4.0 or less, and

(ii) contacting said nit removal product with hair for a period of time sufficient to facilitate removal of nits from such hair.

9. The method of claim 8, wherein said nit removal product is contacted with said hair for a period of between five and ten minutes.

10. The method of claim 8, wherein said nit removal product is selected from thegroup consisting of enzymatic or non-enzymatic nit removal formulations.