United States Patent
`Bowser et al.
`
`[19]
`
`[54] PYRITHIONE CONTAINING HAIR
`TREATMENT COMPOSITION
`
`[75]
`
`Inventors: Paul Anthony Bowser. Near Bideford;
`Jonathan David Hague. Wirral;
`Andrew Malcolm Murray. Parkgate.
`all of United Kingdom; Ruby Loo Bik
`Tan-Walker. Chester. Great Britain
`
`[73] Assignee: Chesebrough-Pond's USA Co.,
`Division of Conopco, Inc., Greenwich.
`Conn.
`
`[21] Appl. No.: 677,259
`
`[22]
`
`Filed:
`
`Jul. 9, 19%
`
`[30]
`
`Foreign Application Priority Data
`
`[EP]
`
`European Pat Off ............... 95304935
`
`Jul. 14, 1995
`Int. CL 6
`........................... A61K 7/fY75; AOlN 25/04
`[51]
`[521 u.s. c1 ...................................... 424no.t3; 424n0.17;
`424/DIG. 4; 514/852; 510/121; 510/123
`[58] Fidd of Search ................................ 424nO.l. 70.12.
`424n0.27, 70.28. DIG. 4. 70.17, 70.13;
`514/852; 510/121. 123, 124. 122
`
`[56]
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`I IIIII
`
`I~ 0111111111~ 11111111~1 ~0111111 ~~~I IIIII~ Ill
`5,723,112
`Mar. 3, 1998
`
`US005723112A
`[111 Patent Number:
`[451 Date of Patent:
`
`5,624,666
`
`4/1997 Coffindaffer et al ..
`
`FOREIGN PATENT DOCUMENTS
`
`0 093 601
`0 136 914
`0 173 259
`0 530 974
`05/194157
`wo 95/02389
`wo 95/22311
`
`ll/1983
`4/1985
`3/1986
`3/1993
`8/1993
`1/1995
`8/1995
`
`European Pat. Off ..
`European Pat. Off ..
`European Pat. Off ..
`European Pat. Off ..
`Japan.
`WlPO.
`WlPO.
`
`Primary Examiner-Edward J. Wehman
`Attorney, Agent, or Firm-Milton L. Honig
`
`[57]
`
`ABSTRACT
`
`The invention provides an antimicrobial hair treatment com(cid:173)
`position for topical application to human hair in the treat(cid:173)
`ment of, for example, dandruff, including:
`(a) at least one surfactant;
`(b) fine particles of an insoluble particulate metal
`pyrithione, in which at least about 90% by weight of the
`particles have a size of 5 microns or less; and
`(c) a polymeric, water-soluble cationic deposition aid for
`the fine particles.
`
`The compositions have good mechanical stability. optical
`properties and anti-dandruff ability.
`
`3,580,853
`
`5/1971 Paman, Jr ............................... 252/152
`
`8 Claims, No Drawings
`
`1
`
`

`
`5,723,112
`
`1
`PYRITHIONE CONfAINING HAIR
`TREATMENT COMPOSITION
`
`FIELD OF THE INVENTION
`
`This invention relates to antimicrobial hair treatment
`compositions for topical application to human hair for the
`treatment of. for example. dandruff. In particular. the inven(cid:173)
`tion relates to an aqueous hair treatment composition com(cid:173)
`prising a surfactant. water-insoluble antimicrobial particles
`having a specific particle size distribution and a cationic
`polymer which serves to enhance the deposition and reten(cid:173)
`tion of the particles on the hair and/or the scalp from the
`composition.
`
`BACKGROUND AND PRIOR ARf
`
`2
`acceptable products. There may also be sensory negatives to
`the user due to sedimentation of the agglomerates onto the
`hair in large sticky lumps. Consequently. deposition can be
`uneven and bioavailability of the active substance to the hair
`5 can be reduced. leading to loss of anti-dandruff benefit.
`Detergent compositions. for example shampoos, compris(cid:173)
`ing an anionic surfactant. water-insoluble particles and a
`cationic polymer have been described in U.S. Pat. No.
`3.580.853 (Parran). In the detergent compositions described
`10 in that patent the cationic polymers are water-soluble cat(cid:173)
`ionic nitrogen-containing polymers. in particular quaternary
`nitrogen substituted cellulose ether derivatives. It appears
`that the deposition enhancement of the water-insoluble
`particles derives from the presence of a complex between
`15 the anionic surfactant and the cationic polymer which is
`formed upon dilution of the detergent composition. Washing
`compositions comprising an anionic surfactant. a water(cid:173)
`insoluble particulate substance and a water-soluble cationic
`polymer which is a non-cellulose cationic polymer are
`20 described in EP 93 601.
`Neither U.S. Pat. No. 3,580.853 or EP 93 601 contain any
`specific teachings on the nature or particle size of the
`particulate substance concerned-this may be an antimicro(cid:173)
`bial such as ZnPfO and can have a particle diameter ranging
`anywhere from about 0.2 up to about 50 microns.
`It has now been found that antimicrobial hair treatment
`compositions which have good mechanical stability, and
`excellent anti-dandruff ability can be obtained by utilising
`fine particles of insoluble particulate metal pyrithione in
`combination with a deposition aid.
`
`Insoluble particulate metal pyrithiones are acknowledged
`as antimicrobial agents which can be incorporated into
`antimicrobial compositions. such as antidandruff hair sham(cid:173)
`poos and conditioners. The zinc salt (hereinafter referred to
`as ZnPTO) is widely used in this context. Generally. dis(cid:173)
`persed particles of the ZnPfO are suspended in the
`composition, which is then applied to the hair to deposit the
`ZnPTO on the hair and scalp.
`A problem encountered with such compositions is that it 25
`is difficult to obtain a stable dispersion containing ZnPfO.
`since its density can lead to separation during storage. Steps
`taken to prevent separation of the ZnPfO particles have
`hitherto included restriction of the formulational base to
`highly viscous emulsions or gels. e.g .. by incorporation of 30
`thickeners or bulking agents. such as clays or pearlescers. to
`give structural viscosity to the system and prevent ZnPfO
`settlement. Such an approach is frequently impractical for
`shampoo compositions. and can give cloudy, aesthetically-
`inferior products.
`EP-A-0 173 259 describes how this stability problem is
`particularly acute in the case of fine particulate ZnPfO.
`which is said to be very sensitive to conditions of liquid
`media for dispersion. and apt to coagulate in the presence of
`··-"
`d
`.
`. 40
`electrolytes such as salts. shampoo sw.actants an catiomc
`polymers. The reference discloses stabilisation of fine par(cid:173)
`ticulate ZnPfO in water by means of a specific dispersant.
`which may include a partly quaternised hydroxyalkylcellu(cid:173)
`lose derivative. or a particular type of copolymeric quater-
`nised cationic polymer blended with at least one inorganic
`salt. Only suspension stability is discussed; the reference
`does not address the issue of effective deposition of the
`ZnPTO active agent onto the hair during use.
`By the very nature of the form in which particles of 50
`ZnPTO are incorporated into hair treatment compositions.
`the anti-dandruff benefits attainable are frequently limited.
`owing to a poor level of deposition of the particles on the
`intended site, e.g., the hair and/or the scalp. meaning that the
`majority of the particles remain suspended in the composi- 55
`tion and are washed away during rinsing of the composition
`from the hair.
`EP-A-136914 describes an antidandruff hair care compo(cid:173)
`sition containing ZnPfO which gives enhanced ZnPfO
`deposition on the scalp. This is said to be due firstly to the
`larger particle size of the agglomerates used, at least 20% of
`which have a size of at least 5 microns, and, secondly. to the
`absence. in the composition. of "deposition interfering poly(cid:173)
`meric and clay type suspending agents".
`The problems encountered with this approach are.
`however. that utilisation of large agglomerates of ZnPfO
`can give rise to difficulties in formulating aesthetically
`
`35
`
`45
`
`SuMMARY OF THE INVENTION
`Accordingly. in one aspect the present invention provides
`an antimicrobial hair treatment composition comprising:
`(a) at least one surfactant;
`(b) fine particles of an insoluble particulate metal
`pyrithione. in which at least about 90% by weight of the
`particles have a size of 5 microns or less; and
`(c) a polymeric water-soluble cationic deposition aid for
`the fine particles.
`
`DEfAll..ED DESCRIPfiON AND PREFERRED
`EMBODIMENTS
`The insoluble particulate metal pyrithione may be repre(cid:173)
`sented by the following general formula:
`
`M n N
`
`S
`
`~ 0
`
`in which M is a polyvalent metal ion and n corresponds to
`the valency of M.
`Preferred examples of M include magnesium. barium.
`strontium. zinc. cadmium. tin and zirconium. Especially
`60 preferred is zinc.
`The fine particles of metal pyrithione have a size distri(cid:173)
`bution in which at least about 90% of the particles have a
`size of 5 microns or less. Preferably. the size distribution is
`such that at least about 90% of the particles have a size of
`65 1 micron or less. It is thought that this small size enables the
`antimicrobial particles to be delivered down to the hair
`follicle, leading to a better efficacy.
`
`2
`
`

`
`5,723,112
`
`3
`Various methods for producing fine particles of metal
`pyrithlone are described, for example, in EP-A-0 173 259.
`The amount of metal pyrithione incorporated into the
`compositions of the invention may depend on the type of
`composition and the exact nature of the material used. A 5
`preferred amount of metal pyrithione is from about 0.001 to
`about 5% by weight of the total composition, more prefer(cid:173)
`ably from about 0.1 to about 3% by weight.
`The composition according to the invention comprises at
`least one surfactant, preferably chosen from anionic. 10
`cationic. nonionic, amphoteric and zwitterionic surfactants.
`and mixtures thereof.
`A particularly preferred hair treatment composition in
`accordance with the invention is a shampoo composition in
`which at least one surfactant provides a deterging benefit. 15
`The deterging surfactant is preferably selected from anionic.
`nonionic. amphoteric and zwitterionic surfactants, and mix(cid:173)
`tures thereof.
`Suitable anionic surfactants include the alkyl sulphates.
`alkyl ether sulphates. alkaryl sulphonates, alkanoyl 20
`isethionates. alkyl succinates, alkyl sulphosuccinates.
`N-alkoyl sarcosinates. alkyl phosphates. alkyl ether
`phosphates, alkyl ether carboxylates. and alpha-olefin
`sulphonates, especially their sodium. magnesium ammo(cid:173)
`nium and mono-. eli- and triethanolamine salts. The alkyl and 25
`acyl groups generally contain from 8 to 18 carbon atoms and
`may be unsaturated. The alkyl ether sulphates. alkyl ether
`phosphates and alkyl ether carboxylates may contain from
`one to 10 ethylene oxide or propylene oxide units per
`molecule. and preferably contain 2 to 3 ethylene oxide units 30
`per molecule.
`Examples of suitable anionic surfactants include sodium
`oleyl succinate. ammonium lauryl sulphosuccinate, ammo(cid:173)
`nium lauryl sulphate, sodium dodecylbenzene sulphonate.
`triethanolamine dodecylbenzene sulphonate. sodium cocoyl 35
`isethlonate. sodium lauroyl isethionate and sodium N-lauryl
`sarcosinate. The most preferred anionic surfactants are
`sodium lauryl sulphate, triethanolamine lauryl sulphate.
`triethanolamine monolauryl phosphate. sodium lauryl ether
`sulphate lEO. 2EO and 3EO. ammonium lauryl sulphate 40
`and ammonium lauryl ether sulphate lEO, 2EO and 3EO.
`Nonionic surfactants suitable for use in compositions of
`the invention may include condensation products of ali(cid:173)
`phatic (C8-C 18) primary or secondary linear or branched
`chain alcohols or phenols with alkylene oxides. usually 45
`ethylene oxide and generally having from 6 to 30 ethylene
`oxide groups. Other suitable nonionics include mono- or
`di-alkyl alkanolamides. Example include coco mono- or
`diethanolarnide and coco mono-isopropanolarnide.
`Amphoteric and zwitterionic surfactants suitable for use so
`in compositions of the invention may include alkyl amine
`oxides. alkyl betaines, alkyl arnidopropyl betaines. alkyl
`sulphobetaines (sultaines). alkyl glycinates, alkyl
`carboxyglycinates. alkyl amphopropionates. alkylam(cid:173)
`phoglycinates alkyl arnidopropyl hydroxysultaines. acyl tau- 55
`rates and acyl glutamates. wherein the alkyl and acyl groups
`have from 8 to 19 carbon atoms. Examples include lauryl
`amine oxide. cocodimethyl sulphopropyl betaine and pref(cid:173)
`erably lauryl betaine. cocarnidopropyl betaine and sodium
`cocamphopropionate.
`The surfactants are present in shampoo compositions of
`the invention in an amount of from 0.1 to 50% by weight.
`preferably from 0.5 to 30% by weight.
`Hair treatment compositions in accordance with the
`invention may also take the form of hair conditioning 65
`compositions. which preferably comprise one or more cat(cid:173)
`ionic surfactants. The use of cationic surfactants is espe-
`
`4
`dally preferred, because these ingredients are capable of
`providing conditioning benefits to hair.
`Examples of cationic surfactants include:
`quaternary ammonium hydroxides, e.g .. tetramethylam(cid:173)
`monium hydroxide. alkyltrirnethylammonium hydroxides
`wherein the alkyl group has from about 8 to 22 carbon
`atoms, for example octyltrimethylammonium hydroxide,
`dodecyltrimethyammonium hydroxide. hexadecyltrimethy(cid:173)
`lammonium hydroxide. cetyltrimethylammonium
`hydroxide, octyldimethylbenzylammonium hydroxide.
`decyldimethylbenzy1ammonium hydroxide. stearyldi(cid:173)
`methylbenzylammonium hydroxide, didodecyldimethylam(cid:173)
`monium hydroxide, dioctadecyldimethylammon.ium
`hydroxide, tallow trimethylammonium hydroxide, cocotri-
`methylammonium hydroxide. and the corresponding salts
`thereof. e.g .. chlorides
`Cetylpyridinium hydroxide or salts thereof. e.g .. chloride
`Quaternium -5
`Quaternium -31
`Quaternium -18
`and mixtures thereof.
`In hair conditioning compositions according to the
`invention. the level of cationic surfactant is preferably from
`0.01 to 10%, more preferably 0.05 to 5%, most preferably
`0.1 to 2% by weight of the composition.
`Hair treatment compositions of the invention may also
`contain one or more conditioning agents. as are well known
`in the art. The conditioning agents may include silicones.
`protein hydrolyzates. quaternised protein hydrolysates and
`other materials which are known in the art as having
`desirable hair conditioning properties.
`Silicones are the most preferred conditioning agents.
`Suitable silicones include volatile and non-volatile
`silicones. such as for example polyalkylsiloxanes. polyalky(cid:173)
`laryl siloxanes, siloxane gums and resins. cyclomethicones.
`arninofunctional silicones. quaternary silicones and mix-
`tures thereof. Silicone oil is a particularly preferred condi(cid:173)
`tioning agent for hair. The silicone may be in the form of a
`low viscosity oil which may contain a high viscosity oil or
`gum in solution. Alternatively. the high viscosity material
`may be in the form of an emulsion in water. The emulsion
`may be of high viscosity oil or of a solution of gum in a
`lower viscosity oil. The particle size of the oil phase may be
`anywhere in the range from 30 nanometers to up to 20
`microns average size.
`The silicone oil may suitably be a polydimethylsiloxane
`with an average particle size of less than 20 microns and
`preferably less than 2 microns. Small particle size enables a
`more uniform distribution of silicone conditioning agent for
`the same concentration of silicone in the composition.
`Advantageously. a silicone with a viscosity in the range
`1-20 million est is used. The silicone is preferably emulsion(cid:173)
`polymerised. since this enables silicones of very high vis(cid:173)
`cosity to be more easily processed. The silicone can be
`eros s-linked.
`Suitable protein hydrolysates include lauryl dimonium
`hydroxy propylarnino hydrolysed animal protein. available
`commercially under the trade name LAMEQUPJ L. and
`hydrolysed keratin containing sulphur-bearing amino acids.
`60 available commercially under the trade name CROQUPJ
`WKP.
`In accordance with the invention. the hair treatment
`composition contains a polymeric water-soluble cationic
`deposition aid for the fine particles. By "deposition aid" is
`meant an agent which enhances deposition of the fine
`particles of metal pyrithione on the intended site, i.e .. the
`hair and/or the scalp.
`
`3
`
`

`
`5
`
`5
`The deposition aid will generally be present at levels of
`from 0.01 to 5%, preferably from about 0.5 to 1%, more
`preferably from about 0.08% to about 0.5% by weight.
`Preferably the cationic charge density of the deposition
`aid, which is defined as the reciprocal of the molecular
`weight of a monomeric unit of the polymer containing 1
`charge, is at least 0.1 meq/g, preferably above 0.8 or higher.
`The cationic charge density should not exceed 4 meqlg. it is
`preferably less than 3 and more preferably less than 2 meqlg.
`The charge density can be measured using conductimetric
`analysis and should be within the above limits at the desired
`pH of use, which will in general be from about 3 to 9 and
`preferably between 4 and 8.
`Preferred deposition aids are cationic derivatives of guar
`gum and cationic polyacrylamides.
`Suitable cationic derivatives of guar gum are JAGUAR
`C13S. which has a low degree of substitution of the cationic
`groups and high viscosity. JAGUAR C15. having a moder-
`ate degree of substitution and a low viscosity, JAGUAR C17
`(high degree of substitution, high viscosity). JAGUAR C16,
`which is a hydroxypropylated cationic guar derivative con(cid:173)
`taining a low level of substituent groups as well as cationic
`quaternary ammonium groups, and JAGUAR 162 which is
`a high transparency, medium viscosity guar having a low
`degree of substitution.
`A particularly preferred deposition aid is Jaguar C13S
`with a cationic charge density of 0.8 meqlg. Other particu(cid:173)
`larly suitable materials include Jaguar C15, Jaguar C17 and
`Jaguar C16 and Jaguar C162.
`Suitable cationic polyacrylamides are described in WO
`95/22311.
`The composition may further comprise from 0.1 to 5% of
`a suspending agent. Examples are polyacrylic acids. cross
`linked polymers of acrylic acid. copolymers of acrylic acid
`with a hydrophobic monomer, copolymers of carboxylic
`acid-containing monomers and acrylic esters. cross-linked 35
`copolymers of acrylic acid and acrylate esters, het(cid:173)
`eropolysaccharide gums and crystalline long chain acyl
`derivatives. The long chain acyl derivative is desirably
`selected from ethylene glycol stearates, alkanolamides of
`fatty acids having from 16 to 22 carbon atoms and mixtures 40
`thereof. Polyacrylic acid is available commercially as Car(cid:173)
`bopol 420. Carbopol 488 or Carbopol 493. Polymers of
`acrylic acid cross-linked with a polyfunctional agent may
`also be used, they are available commercially as Carbopol
`910, Carbopol 934. Carbopol 940. Carbopol 941 and Car- 45
`bopol 980. An example of a suitable copolymer of a car(cid:173)
`boxylic acid containing a monomer and acrylic acid esters is
`Carbopol 1342. All Carbopol materials are available from
`Goodrich and Carbopol is a trade mark. A further suitable
`suspending agent is dihydrogenated tallow phthalic acid 50
`amide (available from Stepan Chemical Co. under the trade(cid:173)
`mark Stepan TAB-2)
`Suitable cross linked polymers of acrylic acid and acrylate
`esters are Pemulen TR1 or Pemulen TR2. A suitable het(cid:173)
`eropolysaccharide gum is xanthan gum. for example that 55
`available as Kelzan mu.
`Another ingredient that may advantageously be incorpo(cid:173)
`rated into hair treatment compositions of the invention is a
`fatty alcohol material. The use of these materials is espe(cid:173)
`cially preferred in conditioning compositions of the 60
`invention, in particular conditioning compositions which
`comprise one or more cationic surfactant materials. The
`combined use of fatty alcohol materials and cationic surfac(cid:173)
`tants in conditioning compositions is believed to be espe(cid:173)
`cially advantageous, because this leads to the formation of 65
`a lamellar phase. wherein the cationic surfactant is
`dispersed.
`
`6
`Preferred fatty alcohols comprise from 8 to 22 carbon
`atoms, more preferably 16 to20. Examples of preferred fatty
`alcohols are cetyl alcohol and stearyl alcohol. The use of
`these materials is also advantageous in that they contnbute
`to the overall conditioning properties of compositions of the
`invention.
`The level of fatty alcohol materials is conveniently from
`0.01 to 10%. preferably from 0.1 to 5% by weight of the
`composition. The weight ratio of cationic surfactant to fatty
`10 alcohol is preferably from 10:1 to 1:10. more preferably
`from 4:1 to 1:8, most preferably from 1:1 to 1:4.
`The hair treatment compositions of the invention are
`preferably aqueous based. The compositions suitably com(cid:173)
`prise water in amount of from about 20 to about 99% by
`15 weight of the total composition.
`The compositions of the invention are preferably rinse-off
`compositions. i.e., suitable for applying to the hair and/or
`scalp, left thereon for an appropriate period of time and then
`rinsed off with water. Thus, shampoos are a particularly
`20 preferred product form for compositions of the invention.
`Depending on the type of composition employed. one or
`more additional ingredients conventionally incorporated
`into hair treatment formulations may be included in the
`compositions of the invention. Such additional ingredients
`25 include opacifiers such as polyethylene glycol distearate and
`ethylene glycol stearates. polymer lattices, additional anti(cid:173)
`microbial agents. foam boosters. perfumes. colouring
`agents. preservatives, viscosity modifiers, proteins.
`polymers. buffering or pH adjusting agents. moisturising
`30 agents, herb or other plant extracts and other natural ingre(cid:173)
`dients.
`The invention is further illustrated by way of the follow(cid:173)
`ing non-limitative examples.
`
`EXAMPLES 1 & 2
`Hair shampoo compositions in accordance with the
`present invention. comprising fine particulate metal
`pyrithione and a deposition polymer were prepared. The two
`compositions had the following formulations.
`
`INGREDIENf
`
`EXAMPLE l
`
`EXAMPLE2
`
`% BYWEIGIIT
`
`Sodium Iaury! ether
`sulphate 2EO (28% active)
`Cocamidopropyl betaine
`(30% active)
`Jaguar C13S
`Zinc pyrithione, fin<> particle
`size (48% active)
`CARBOPOL 980
`Ethylene glycol monostearate
`Dimcthicone (60% aqueous
`emulsion)
`Zinc sulphate heptahydrate
`Vitamin E acetate
`Preservative, colour,
`fragrance
`Water
`
`50
`
`50
`
`6.7
`
`0.1
`2.08
`
`0.4
`3.0
`1.7
`
`0.1
`0.05
`
`6.7
`
`0.1
`2.08
`
`0.4
`3.0
`3.34
`
`0.1
`0.05
`
`q.s.
`
`to 100%
`
`Both shampoos gave excellent anti-dandruff performance
`on the hair. and were stable without visible signs of sepa(cid:173)
`ration after three months storage both at room temp·erature
`and at 45° C.
`
`EXAMPlE 3
`A series of compositions were prepared to test the level of
`deposition on skin of zinc pyrithione from formulations
`
`4
`
`

`
`5.723,112
`
`7
`according to the invention compared with control formula(cid:173)
`tions containing no deposition polymer, and to demonstrate
`the effect of reducing the particle size of the zinc pyrithione.
`
`Composition (% wt)
`
`Ingredient
`
`&xliwnlawylernerswphme
`Cocamidopropylbetaine
`Dimetbicone emmsionC' 1
`Zinc pyritbioneC2l
`Zinc pyritbioneC3l
`Carbomer
`Guar hydroxypropyl trimoniwn
`chloride
`VeegwnC4l
`
`A
`
`14
`2
`
`0.6
`
`B
`
`14
`2
`1
`
`1
`0.6
`0.1
`
`c
`
`14
`2
`
`0.6
`0.1
`
`''>x2-1766 gum, ex Dow Coming
`t2lzinc pyrithione ex Olin, 90% of particles size less than 1 micron
`C3lzinc pyrithione ex Olin, 90% of particles size less than 5 micron
`c•:>colloidal magnesium aluminium silicate, ex R. T. Vanderbilt
`
`8
`wavelength dispersive X-ray fluorescence spectrometer. The
`nett zinc counts were obtained by subtracting the counts
`obtained from blank tape strips from the gross Zinc counts.
`The results are shown below in Table 1:
`
`TABLE 1
`
`Composition
`
`Zinc deposited (Kcounts/s)
`
`A
`B
`c
`
`0.23
`0.45
`0.63
`
`5
`
`10
`
`15
`
`Comparison of the level of zinc deposition from Compo(cid:173)
`sitions A and B respectively shows a statistically significant
`difference. with a confidence level of >99%. in favour of
`composition B. containing cationic deposition polymer.
`Comparison of the level of zinc deposition from Compo(cid:173)
`sitions B and C respectively shows a statistically significant
`20 difference. with a confidence level of >99%. in favour of
`composition C, containing smaller particle size zinc
`pyrithione.
`We claim:
`1. An antimicrobial hair treatment composition compris(cid:173)
`ing:
`
`25
`
`Each of the above Compositions A to C was subjected to
`a standard deposition test on skin and the level of zinc
`pyrithione deposited in each case was measured using the
`technique of X-ray fluorescence. The methods used are
`described below:
`Panellist Selection
`Ten panellists (5 male and 5 female; age 18-60 years)
`were recruited from volunteers who did not suffer from any
`skin disorders such as psoriasis or eczema.
`Test Procedure
`On each inside forearm., six circular areas of diameter 25 30
`mm were marked using ball-point pen. Before product
`application, one of the circles on each forearm was tape(cid:173)
`stripped using J-Clear tape. Pressure was applied to the
`taped area for 30 seconds using a rubber press. This initial
`tape strip was used to determine the baseline reading.
`a) Calibration
`For the calibration test, on each of the remaining area, 20
`J.il of diluted ZnPfO Fine Particle Size grade *(ex. Olin) was
`applied and allowed to dry. The final amounts of ZnPfO
`dosed at each of the sites were 0.1,2,5 and 10 ~g/cm2 of 40
`ZnPTO. The calibration was then repeated on the other arm.
`*(Fine Particle Size grade: 90% of ZnPTO particles have
`less than 1 micron size).
`b) Composition Application
`On each of the remaining areas. each composition was
`applied as follows:
`Apolythene cylinder of inner diameter 25 mm was placed
`on the marked circle and pressed to the skin to make a seal.
`100 J.il of tenfold diluted composition (3 g composition
`diluted with 27 g distilled water) was applied to the marked
`area and agitated for 30 seconds using a glass rod. The
`composition was then rinsed with 2x5 ml of distilled water.
`directed over the application area using a syringe.
`The test compositions were applied to designated sites
`according to a balanced position allocation to minimise any
`bias. Replicates were carried out using a repeat design after
`randomising row positions.
`After 15 minutes of drying. each circle was tape-stripped
`using J-Clear tape. Pressure was applied to each taped area
`for 30 seconds using a rubber press. Zinc counts on the
`tape-strips were measured using X-ray fluoresence spectros-
`copy.
`XRF Fluorescence Spectroscopy Analysis of Zinc and Sul(cid:173)
`phur Content
`The tape strips were mounted on aluminium rings and
`measured for zinc and sulphur using a Philips PW2400
`
`(a) from 0.1 to 50% by weight of surfactant;
`(b) from 0.001 to 5% by weight of fine particles of an
`insoluble particulate metal pyrithione. in which at least
`about 90% by weight of the particles have a size of 1
`microns or less; and
`(c) from 0.01 to 5% by weight of a polymeric. water(cid:173)
`soluble cationic deposition aid for the fine particles.
`2. A composition according to claim 1 in which metal
`pyrithione is zinc pyrithione.
`3. A composition according to claim 1 in which the metal
`pyrithione is present in the composition in an amount of
`from about 0.1 to about 3% by weight.
`4. A composition according to claim 1 in which the
`deposition aid is a cationic derivative of guar gum or a
`cationic polyacrylamide.
`S. A composition according to any preceding claim. which
`is shampoo composition. in which at least one surfactant is
`selected from anionic. nonionic. amphoteric and zwitteri(cid:173)
`onic surfactaots, and mixtures thereof, in a total amount of
`from about 0.5 to 30% by weight of the composition.
`6. A composition according to claim 1. which further
`comprises a conditioning agent selected from volatile and
`non-volatile silicones.
`7. A method of treating dandruff comprising applying to
`the hair an antimicrobial composition comprising:
`(a) from 0.1 to 50% by weight of surfactant;
`(b) from 0.001 to 5% by weight of fine particles of an
`insoluble particulate metal pyrithione. in which at least
`about 90% by weight of the particles have a size of 1
`microns or less; and
`(c) from 0.01 to 5% by weight of a polymeric. water(cid:173)
`soluble cationic deposition aid for the fine particles.
`8. A composition according to claim 4 wherein the cat(cid:173)
`ionic deposition aid is guar hydroxypropyl trimonium
`chloride.
`
`* * * * *
`
`35
`
`45
`
`50
`
`55
`
`60
`
`5