FIELD OF THE INVENTION
The. present invention relates to personal care formulations comprising zinc pyrithione.
More particularly, the invention relates to transparent personal care formulation having
high anti-fungal activity, comprising zinc pyrithione, hydrotropcs. surfactant systems
(anionic, cationic. amphoteric and non-ionic) and optionally, water-soluble imidazoles
containing amino acids/derivatives; and an in situ single step process for preparation of
the same.
BACKGROUND AND THE PRIOR ART
Zinc pyrithione (ZPTO), also known as zinc pyridine-2-thiol-N-oxide or bis [1-hydroxy-2
(H) pyridinethionato]-zinc is a broad spectrum antimicrobial agent and is the most
acknowledged anti-dandruff agent owing to its anti-fungal activity. However being
insoluble in water, when used in personal care formulations, especially in shampoo as
antifungal agents, it produces white suspension that precipitate in the packaging bottle.
Recommended usage level of ZPTO is 1 -2 % w/w because of its insolubility. But it is
perceived harsh by the consumers (US 2006 0182696 Al).
The antifungal and anti microbial activity of ZPTO depends on the bioavailability of
aqueous intact ZPTO molecule. As the solubility of ZPTO in aqueous solution is very
low (6-12 ppm). availability of ZPTO molecule in aqueous solution is also low.
Therefore to overcome these disadvantages (precipitations and low water solubility of
ZPTO) ZPTO is generally used in excess (1-2% w/w).
It has been suggested that cationic polymers can increase the efficacy of zinc pyrithione
in anti dandruff shampoos by enhancing the deposition and retention of the water
insoluble ZPTO particles on scalp. US 3,489,686 teaches polyethylenimine or the
reaction product of polyethylenimine and ethylene oxide or propylene oxide; US
3.580,853 teaches cationic homopolymer comprising particulate cellulose derivative and
US 3,761.417 teaches piperidinum chloride which can increase the efficacy of ZPTO.

In the prior art cationic polymers have been used to enhance deposition. But these
cationic polymers would deposit more on hair, as hair is more anionic in nature than
scalp. So, deposition on scalp would be low compared to hair. In the present invention,
the deposition is not electrostatically controlled and hence will be even for scalp and hair.
Moreover, cationic polymers show problem in fonnulation compatibility, when added
with anionic surfactants resulting in loss of transparency and drop in viscosity.
U.S. 3,940,482 teaches clear liquid composition of zinc pyrithione solubilized by adding
a polyethylenimine (quaternary ammonium compound) to a suspension of the pyrithione
complex in water for use as a bactericide or fungicide. However ZPTO solubilized in
alcohol/water using polyethylenimine (quaternary ammonium compound) has a pH of
about 9.0. Reducing pH to <8.0 leads to destabilization of mixture. It is further known
that ZPTO at alkaline pH (>8) is photo unstable.
US 6162446 teaches use of Zinc pyrithione with surfactant and water/alcohol. US
2006/0171911 teaches use of (0.001-10% by weight, preferably 0.1-3% by weight) of
surfactant, such as diiodomethyl-p-tolylsulfone for reducing the lability of particulate
Zinc material (0.001-10% by weight). However these prior arts do not teach increase in
antifungal activity of ZPTO along with solubilizing the same.
Thus there is a need to solubilize ZPTO and thereby increase its efficacy in personal care
formulations such that ZPTO remains solubilized and maintains transparency under
storage conditions. Therefore, solubilized ZPTO helps to retain the transparency in
transparent personal care formulations and simultaneously enhance its anti dandruff
efficacy.
OBJECTS OF THE INVENTION
It is one of the objects of the present invention to overcome the drawbacks of the prior
art.

It is another object of the present invention to provide composition comprising ZPTO
stable at pH 5.5 -8.5, most preferably 6.5-7.5 in formulations without any pre-
formulation and difficulty of stability or precipitation.
It is yet another object of the present invention to provide 0.01 - 1% w/w of ZPTO which
has increased antifungal efficacy.
It is yet another object of the present invention to provide ZPTO comprising transparent
personal care formulation, especially in antidandruff shampoo, antidandruff hair gel,
antidandruff hair soap, hair care serums, anti acne products, and conditioners.
It is yet another object of the present invention to provide a personal care formulation that
contains reduced levels of ZPTO without hampering its desired antifungal and/or
antimicrobial activity.
It is yet another object of the present invention to provide environmental friendly
personal care products comprising as low as 0.03% w/w of ZPTO with the desired
antifungal and/or antimicrobial activity.
SUMMARY OF THE INVENTION
According to one aspect of the present invention, a stable transparent formulation is
provided, the said formulation comprising
0.01% to about 1% w/w Zinc Pyrithione;
0.01 % to about 50% w/w hydrotropes;
0.01 % to about 50% w/w surfactant
According to another aspect of the present invention a stable transparent personal care
formulation is provided, the said formulation comprising:
0.01% to about 1% w/w Zinc Pyrithione;
0.01 % to about 50% w/w hydrotropes;
0.01 % to about 20% w/w amino acid most preferably water soluble imidazole
containing amino acids/derivatives and
optionally 0.01 % to about 50% w/w surfactant

According to another aspect of the present invention there is provided a process for
production of the stabilized transparent personal care formulation, said process
comprising steps of:
1. Preparing a solution of hydrotropes in water
2. Adding ZPTO in the solution mentioned in step 1
3. Mixing the above mixture obtained from steps 1 and 2
4. Adding the mixture obtained in step 3 in surfactant solution
5. Stirring the above mixture obtained in step 4 to get the transparent formulation.
According to another aspect of the present invention there is provided a process for
production of the stabilized transparent personal care formulation, said process
comprising steps of:
1. Preparing a solution of hydrotropes and amino acid in water
2. Adding ZPTO in the solution mentioned in step 1
3. Stirring the above mixture obtained from steps 1 and 2 to get a transparent
solution
4. Optionally adding the mixture obtained in step 3 into a surfactant solution
DETAILED DESCRIPTION OF THE INVENTION
The present invention provides a transparent personal care formulation having high anti-
fungal activity, comprising zinc pyrithione. hydrotropes, surfactant systems (ionic,
amphoteric and non-ionic) and optionally, water-soluble imidazoles containing amino
acids/derivatives; and an in situ single step process for preparation of the same.
The transparent personal care formulation comprises of 0.01% to about 1% by weight of
ZPTO; more preferably 0.01 % to about 0.5 % by weight.
The amount of hydrotropes present in the transparent personal care formulation is about
0.01 to 50 % w/w preferably from 1 to 20 % w/w. The hydrotropes is selected from

chemical entity chosen from sodium-X-sulphonate, where X can be xylene, cumin or p-
toluene and mixtures thereof.
Non-limiting examples include but not limited to Sodium benzoate, Sodium salicylate,
sodium benzene sulphonate, sodium benzene 1,3, di sulphonate, pregnane 20 carboxylic
acid.
The surfactant system in the formulation of the present invention may be ionic or
nonionic or both. The surfactants (anionic, cationic, amphoteric and non-ionic) are
present in an amount of 0.01% to 50% w/w, preferably 0.01 % to 14% w/w. The ionic
surfactants are selected from but not limited to anionic and cationic. The anionic
surfactants are selected from sodium or potassium salts of long chain sulphates having
carbon chain lengths 6-14 most preferably sodium/ammonium lauryl or laureth sulphate,
amino acid derived surfactants most preferably sodium sarcosinate/glycinate. The
cationic surfactants are selected from cetyl trimethyl ammonium chloride and bromide
The non-ionic surfactants are selected from Polyoxyethylene (20) sorbitan monooleate
(Tween 80). Polyoxyethylene (20), sorbitan monolaurate (Tween 20), ethoxylated
sorbitan monolaurate (Crillet 180). The amphoteric surfactants are selected from
cocamidopropyl betaine (CAPB) or Cocamide (DEA),.
The transparent personal care formulation according to the present invention optionally
comprises water-soluble imidazole containing amino acids/derivatives, which may be
present in an amount of 0.01 to 20 % w/w; preferably from 0.1 to 5 % w/w. The amino
acid most preferably water-soluble imidazole containing amino acids/derivatives is
selected from histidine, proline, Na-PCA or its derivatives and mixtures thereof.
A co-pending patent application, bearing Application No. 1265/KOL/2009 teaches an
aqueous transparent solution for use in personal care formulations, where the solution
comprised of ZPTO, amino acid and/or its derivatives, imidazole and/or its derivatives,
organic compounds with thiol functionality and buffer salts. The ZPTO solution in
1265/KOL/2009 required pH adjustment, preformulation of the actives, and the
antifungal activity was also less as compared to the present invention. Further the loading

capacity of ZPTO in the solution is less and the solution is transparent in the pH range of
7 to 8. The present invention on the other hand provides a formulation, comprising of
ZPTO. amino acids, hydrotropes and surfactants, does not require any pH adjustment,
pre formulation of the actives. The formulation of the present invention has increased
loading capacity of ZPTO, increased antifungal activity and maintains 90% transparency
over a wider range of pH from 5.5 to 8.
Further the present inventors have found that not only the components of the formulation
are responsible for enhanced activity as well as transparency of the formulation, but also
the process by which the formulation is prepared. The order of addition of different
components in the formulation is also crucial in maintaining the transparency of the
formulation of the present invention. The present inventors have found that ZPTO when
added in a mixed solution of hydrotropes and amino acid and then optionally transfer of
the resultant solution to surfactant solution, which provides transparency along with
enhanced antifungal activity.
According to one aspect of the present invention, the transparent personal care
formulation comprises zinc pyrithione, hydrotropes and surfactants.
According to a further aspect of the present invention, the transparent personal care
formulation comprises zinc pyrithione, hydrotropes, amino acid and optionally
surfactants.
The process in accordance to the present invention comprises steps of:
1. Preparing a solution of hydrotropes
2. Adding ZPTO in the solution mentioned in step 1
3. Stirring the above mixture obtained from steps 1 and 2
4. Adding the mixture obtained in step 3 into a surfactant solution
5. Stirring the above mixture obtained in step 4 to get a transparent solution
The process in accordance of the present invention may further comprise step of
optionally addition of amino acid in step 1.

The advantages in using the present transparent formulation is that it can hold
comparatively more amount of ZPTO in solubilized form thereby giving transparency as
well as enhancing the efficacy.
The formulation of the present invention has the advantage that it is not prepared in
alkaline medium (pH >8.5). The amount of imidazole containing amino acid used is not
to alter the pH of the bulk solution instead; it is used to increase the loading efficacy of
ZPTO. Preparation at neutral pH decreases the instability of composition due to
precipitation and thereby increases the stability of the system. Further the ZPTO that is
added into the formulation does not require any pre-formulation method such as
suspension in polymeric matrix, and/or mixing with metal silicates.
The present invention maintains above 90% of transparency at a pH 5-8. The composition
is stable (- 90 % transparency) and no precipitation occurred over a period of three
months at room temperature
The present invention comprising ZPTO can be used in transparent personal care
formulations, especially in antidandruff shampoo, antidandruff hair gel, antidandruff hair
soap, hair care serums, anti acne products and conditioners.
The present invention is illustrated by the following non-limiting examples. It is to be
understood that the disclosed methodology is not limited to the exact details briefed here
and variations to implement the idea are possible. The methodology described is for the
purpose of description and should not be taken as limitation.
Example 1
Composition
.1. 10% (w/w) Hydrotropes, 3% (w/w) Amino acids, 0.2% w/w ZPTO
2. 20% (w/w) of formulation mentioned in stepl was added in Surfactant (anionic,
cationic. amphoteric and nonionic) and the volume was adjusted in such a way
that the final concentration of surfactant becomes 10-20% (w/w)

Preparation:
A solution of hydrolropes and amino acids was mixed and ZPTO was added to it. The
resulting solution was stirred and 20% w/w of the above solution was added to surfactant
with constant stirring at RT. The resulting solution showed a transparency of 90%.
The stability of the composition with time and varying pH was tested and the results are
depicted in the tables below
The sample is stable (~ 90 % transparency) and no precipitation occurred over a period of
three months at room temperature. Stability of the transparent ZPTO solution over a
period of time is given below in tabular form.


Thus the composition of the present invention is stable and transparent for a duration of
12 weeks over a wide range of pH.
Example 2
To study the effect of mixing of the components of the formulation, various samples were
prepared as mentioned below and tested for transparency
1. A solution comprising 3% w/w amino acid and 10% w/w hydrotopes (e.g. sodium
cumin or xylene or p-toluene sulphonate) was prepared and stirred well to
dissolve the amino acid. 0.2% w/w ZPTO was added and stirred well. A
transparent solution was obtained within five minutes.
2. A solution of 10% w/w hydrotropes and 0.2% w/w ZPTO was prepared. To this
3% w/w amino acid was added and stirred well for one hour and a turbid solution
was obtained.
3. All the constituents 10% w/w hydrotropes, 3% w/w amino acid and 0.2% w/w
ZPTO were added and mixed together and stirred well for one hour and a turbid
solution was obtained.
4. A solution of 10% w/w hydrotropes and 0.25% w/w ZPTO was prepared. 20%
w/w of the prepared solution of hydrotropes and ZPTO was mixed with 14% w/w
surfactant solution and stirred well.



Table 1 shows the sequence of addition of the components in the formulation that is
crucial for imparting transparency to the formulation.
Example 3
To study the loading capacity of ZPTO in different combinations, various samples (1 to
4) were prepared as mentioned below and tested for transparency
1. A 3% w/w amino acid solution was prepared and 0.06% w/w ZPTO was added
and stirred well for an hour. The resulting solution is turbid
2. A solution 0.06% w/w ZPTO and 10% w/w hydrotropes was prepared and stirred
well for 1 hr. The resulting solution was turbid
3. A solution comprising 3% w/w amino acid and 10% w/w sodium cumin
sulphonate (NaCuS) or sodium xylene sulphonate (NaXS) was prepared and
stirred well to dissolve the amino acid. 0.1 to 0.2% w/w ZPTO was added and
stirred well. A transparent solution was obtained within five minutes.
4. 25 mg of ZPTO was taken and mixed with 12 gm NaXS and 13 gm water. The
above solution was added to 25 gm SLES 2EO (28% w/w) and stirred for 20
minutes. The solution obtained was transparent.


Table 2 shows that only the formulation in accordance with the present invention gives
the desired characteristics of transparency.
Example 4
To study the antidandruff activity of the formulation, various samples were prepared as
mentioned below and tested using disc diffusion method against M .furfur.
1. 1% vv/w ZPTO dispersion was prepared in water
2. 1% w/w ZPTO in surfactant was prepared by adding lg ZPTO powder, 50g of
28% surfactant and rest water
3. A solution of 3% w/w amino acid and 10% w/w hydrotropes was prepared in
water
4. A 3% w/w amino acid solution was prepared and 0.06% w/w ZPTO was added
and stirred well for an hour.
5. A solution 0.06% w/w ZPTO and 10% hydrotropes was prepared and stirred well
for 1 hr. The resulting solution was turbid
6. A solution comprising 3% w/w amino acid and 10% w/w NaCuS was prepared
and stirred well to dissolve the amino acid. 0.1 to 0.2% w/w ZPTO was added and
stirred well. A transparent solution was obtained within five minutes.
7. 25 mg of ZPTO was taken and mixed with 12 gm NaXS and 13 gm water. The
above solution was added to 25 gm SLES 2EO (28% w/w) and stirred for 20
minutes. The solution obtained was transparent.
For all the samples, the anti-dandruff efficacy was determined using disc diffusion
method against M .furfur, Here 10ul of sample was added on the filter paper disc. Then
the disc was kept in the microbial culture swabbed on the culture media. The culture
plates were incubated at 37°C for 48hrs and the zone was measured.

We claim:
1. A transparent personal care formulation comprising:
0.01% to about 1% w/w Zinc Pyrithione;
0.01 % to about 50 % w/w hydrotropes;
0.01 % to about 50% w/w surfactant; and
aqua.
2. A transparent personal care formulation comprising:
0.01% to about 1% w/w Zinc Pyrithione;
0.01 % to about 50% w/w hydrotropes;
0.01 % to about 20% w/w amino acid most preferably water soluble imidazole
containing amino acids/derivatives;
optionally 0.01% to about 50% w/w surfactant;
and aqua.
3. A transparent personal care formulation as claimed in any of claim 1 or 2 which is
stable at pH 4-8.
4. A transparent personal care formulation as claimed in claim 3 which is stable at
pll 5.5-8.5.
5. The personal care formulation as claimed in any preceding claim comprising
0.01% to 0.5% w/w by weight of said Zinc Pyrithione.
6. The personal care formulation as claimed in any preceding claim, wherein said
hydrotropes is selected from sodium-X-sulphonate, where X is selected from
xylene, cumin, p-toluene.
7. The personal care formulation as claimed in any preceding claim, wherein said
hydrotropes are present preferably in an amount 1 % to 20 % w/w.
8. The personal care formulation as claimed in any preceding claim , wherein said
surfactants are selected from anionic, cationic, amphoteric, non-ionic surfactants

preferably sodium lauryl sulphate, sodium laureth sulphate, cetyl trimethyl
ammonium chloride/bromide, cocamidopropyl betaine (CAPB), Polyoxyethylene
(20) sorbitan monooleate (Tween 80), Polyoxyethylene (20) sorbitan monolaurate
(Tween 20).
9. The personal care formulation as claimed in claim 8, wherein said surfactants are
preferably present in an amount of 0.01 % to 14% by weight.
10. The personal care formulation as claimed in claim 2, wherein said water soluble
imidazole containing amino acids/derivatives is selected from histidine, proline,
Na-PCA or its derivatives and mixtures thereof.
11. The personal care formulation as claimed in claim 2, wherein said water soluble
imidazole containing amino acids/derivatives is present in a preferred amount of
0.1 to 5 % w/w.
12. A process for preparing stabilized transparent personal care formulation, said
process comprising steps of:
(i) preparing a solution of hydrotropes in water;
(ii) adding ZPTO to the solution obtained from step (i);
(iii) stirring the resulting solution from steps (i) and (ii);
(iv) adding the solution obtained in step (iii) to surfactant solution;
(v) stirring the mixture obtained in step (iv) to get a transparent solution.
13. A process for preparing stabilized transparent personal care formulation, said
process comprising steps of:
(i) Preparing a solution of hydrotropes and optionally amino acid in
water;
(ii) Adding ZPTO in the solution mentioned in step (i);
(iii) Stirring the above mixture obtained from steps (i) and (ii)
(iv) Adding the mixture obtained in step (iii) into a surfactant solution and
stirring the mixture to get a transparent solution.

14. The personal care formulation as claimed in any of the preceding claims wherein
the said formulation is selected from antidandruff shampoo, antidandruff hair gel,
antidandruff hair soap, anti-acne products, hair care serums, and conditioners.
15. A personal care formulation and a process for preparation of the same as
described herein with reference to examples.

A transparent personal care formulation having high anti-fungal activity, comprising zinc
pyrithione. hydrotropes, surfactant systems (ionic, amphoteric and non-ionic) and
optionally, water-soluble imidazole containing amino acids/derivatives; and an in situ
single step process for preparation of the same.