US 3726968 A
Antiperspirant compositions containing sodium or lithium tetraarylboron compounds as antiperspirant agents.
Description (OCR text may contain errors)
ilnified States Paiem [191 Loomans 5] Apr. 10, 1973  THE INHIBITION OF PERSPIRATION  References Cited WHTH SODIUM TETRAPHENYLB RON 0 UNITED STATES PATENTS  Inventor: Maurice E. Loomans, Green Town- 2 853 525 9/1958 W al 260/606 5 B v ittla et Hamilton Ohm 2,982,785 5/1961 McKenzie et a1. ..260/606.5 B  Assignee: The Procter & Gamble Com an 3,062,708 11/1962 Updegraff ..260/606.5 B
Cincinnati, Ohio Primary ExaminerStanley J. Friedman Flled: 5, 1971 Assistant Examiner-Donald B. Meyer  Appl' No.2 121,591 Attorney-Jack D. Schaeffer and Richard C. White  ABSTRACT  US. Cl ..424/65, 424/47 Antipersplrant compositions containing sodium or  Int. Cl. ..A61k 7/00 lithium tetraarylboron compounds as antiperspiram  Field of Search ..424/47, 185, 65; a ems 2 Claims, N0 Drawings I BACKGROUND OF THE INVENTION This invention relates to novel compositions for topical application to human skin to inhibit perspiration.
One of the most widely used types of cosmetic compositions are the antiperspirants which are designed to inhibit or reduce unwanted perspiration, especially in the axillae. Such compositions generally contain one or moreingredients which inhibit or arrest perspiration flow when appliedto human skin. These antiperspirant ingredients are thought to react with the sweat duct by any of a variety of mechanisms and to stop perspiration flow either by a physiological action, or by a physical plugging of the sweat duct orifice. Heretofore, commercially available antiperspirant ingredients have been limited almost exclusively to the partially hydrated acid salts of polyvalent metals, for example the aluminum chlorhydrates, aluminum chloralcoholate compounds, zirconium halide hydrates and the like. i
The antiperspirant compounds currently employed all suffer from various defects which limit their utility in wherein M is selected from the group consisting of lithium cation and sodium cation and wherein each sub-' stituent R is an aromatic group having the formula day-to-day cosmetic use. For example, the acid salts of the polyvalent metals sometimes cause an acid reaction on the skin which deteriorates clothing coming in contact therewith. Certain of the known antiperspirant compounds are not sufficiently stable to insure reasonable product shelf life and can cause unacceptable discolorations of clothing and skin after storage. At the same time, it is widely recognized that some antiperspirant 'compounds' appar ently are not effective when applied to certain individuals. For these reasons, there is a continuing search for new, effective antiperspirant compounds capable of being formulated into cosmetically acceptable compositions.
Therefore, it is a primary object of this invention to provide new and effective antiperspirant compositions. It is a further object to provide antiperspirant compositions comprising certain tetraarylboron compounds in combination with certain suitable carriers. These and other objects are obtained by the present invention as will become apparent from the following disclosure.
SUMMARY OF THE INVENTION The present invention is based on the unexpected utility of sodium and lithium tetraarylboron compounds as antiperspirants. This invention thus encompasses antiperspirant compositions comprising tetraarylboron compounds of thetype hereinafter disclosed,
said compositions being substantially free from interfering amines and cations. (The term antiperspirant as used herein encompasses materials that either inhibit, or stop, perspiration flow when applied to the surface of the human skin.)
DETAILED DESCRIPTION OF THE INVENTION In one of its embodiments, the instant invention encompasses an antiperspirant composition comprising: l an amount sufficient to inhibit perspiration (at least about 0.01 percent, by weight, preferably from about 1 percent to about 20 percent, by weight) of a tetraarylboron compound having the general formula MBR wherein R is: hydrogen; lower alkyl (e.g., methyl, ethyl, propyl, butyl, isopropyl,'t-butyl, pentyl, hexyl,
7 and the like); lower alkoxyl (e.g., methoxyl, ethoxyl,
propoxyl, butoxyl, isopropoxyl, t-butoxyl and the like); carboxyalkyl ester, wherein alkyl is C to C or carboxyl; and (2) a compatible, pharmaceutically acceptable carrier as hereinafter detailed. Compounds of formula (I) wherein R is phenyl and R is hydrogen, lower alkoxyl, carboxyl and carboxyalkyl ester, with alkyl being about C to C are preferred for use herein.
This invention also encompasses a method for inhibiting perspiration comprising applying to the human skin an effective amount of a tetraarylboron compound of formula (I), above.
Sodium tetraphenylboron, which is preferred for use 9 the resulting triarylboron compound, all in the manner described by Wittig, et al., Ann. 563, l 10 (1949). The aryl lithium or aryl sodium compound which is reacted with the triarylboron compound can be prepared, for example, by the reaction of lithium or sodium with an aryl halide in the manner well-known in the art. Alternatively, aryl sodium and aryl lithium compounds can be prepared by a metal exchange reaction involving an alkyl metallic compound (e.g., methyl sodium or methyl lithium) with an aromatic compound such as benzene, toluene, naphthalene and the like in the manner described by Rochow, et al., The Chemistry of Organometallic Compounds, J. Wiley and Sons, Chapter 4. By these general procedures are preparedsuch compounds as phenyl lithium, o-tolyl sodium, mtolyl lithium, lithium, diethoxyphenyl sodium, dimethoxyphenyl lithium, a-naphthyl lithium, B- naphthyl lithium, 2,4,6-triisopropyl-phenyl lithium, tetrabutylphenyl lithium, xylyl sodium, naphthyl sodium, phenylethynyl sodium, B-naphthylmethyl sodium and the like. Specific references to the preparation of these and other aryl lithium and aryl sodium compounds are found at page 73 of Rochow, et al., above. The aryl sodium or aryl lithium compound is then allowed to react with the triarylboron compound, 8R with the formation of the corresponding sodium or lithium tetrarylboron product. For example, as described by Wittig, et al., above, addition of phenyl lithium to an ethereal solution of triphenylboron gives lithium tetraphenylboron. A general procedure for the preparation of the complex metal tetrarylboron salts of formula (I) is described more fully in British Pat. 705,719 l954), incorporated herein by reference.
It is also possible to prepare tetraarylboron compounds having mixed aryl groups; this is achieved by reacting an aryl'sodium or aryl lithium compound with a triarylboron compound having different aryl groups. Such materials are also of use herein. References describing the preparation of various sodium and lithium tetraarylboron compounds having mixed aryl groups, e.g., lithium triphenyl-a-naphthylboron, lithium phenyl-tri-oc-naphthylboron, lithium triphenyl-ptolylboron, lithium di-(o-tolyl)diphenylboron, and the like, are found in W. Gerrard, The Organic Chemistry of Boron, 1961 Academic Press, pages 239 and 240. Still another process suitable for preparing compounds of formula (I) suitable for use herein involves reacting NaBF, with four equivalents of an aryl Grignard reagent of the type noted above. It may therefore be seen that any of the sodium and lithium tetrarylboron compounds of formula (I) which are suitable for use in the practice of this invention can be prepared by wellknown methods.
To effect the antiperspirant activity of the sodium or lithium tetraarylboron compounds of formula (I) in the manner of this invention said compounds are applied to the human skin in an amount sufficient to inhibit perspiration. The requisite amount of a sodium or lithium tetraaryl compound of formula (I) will vary since the antiperspirant response to these materials will vary between individuals applying same. In most cases, perspiration, especially axillary perspiration, will be inhibited when at least about LOug. of the sodium or lithium tetraarylboron compound is applied per mm of skin. In some instances less materials will be needed. Most generally, from about 0.1 g. to 5 g. of an antiperspirant composition, as hereinafter described, containing from about 0.01 percent to about 20 percent, by weight, of a sodium or lithium tetraarylboron of formula (I) will be applied to a skin area of about 24 cm with good antiperspirant results. More or less of such compositions can be used, depending on the individual.
It is not necessary that the tetraarylboron compound of formula (I) be dissolved prior to application to effect its antiperspirant action, and, hence, when such materials are applied to human skin in the form ofa power or dust they exhibit a high degree of antiperspirant activity. When the sodium or lithium tetraarylboron compounds of formula (I) are applied as powders in the manner of this invention their state of aggregation is of no consequence in that they perform their antiperspirant function regardless of particle size. For most cosmetic applications it is desirable that materials applied to the skin be impalpable. Therefore, cosmetically acceptable antiperspirant dusts comprising sodium or lithium tetraarylboron compounds of formula (I) should preferably have said boron compound in the state of aggregation smaller than about 37 microns.
In most instances the tetraarylboron compounds of formula (I) will be applied to human skin in conjunction with a carrier of the type hereinafter detailed. A variety of compatible and pharmaceutically acceptable carriers are suitable for this purpose. By compatible is meant that such carriers are substantially free from cations other than sodium and lithium cations and free from amines having a basic dissociation constant (K of or greater, since the compounds of formula (I) precipitate the cations of essentially all of the metals of the periodic chart, other than sodium and lithium, and
amines having K s of lO', or greater. By pharmaceutically acceptable is meant that the carriers are suitable for repeated application to human skin with little, or no, untoward physiological effects.
For example, the sodium or lithium tetrarylboron compounds of formula (I) can be applied to the skin as a solution containing an effective amount, i.e., greater than about 0.01 percent, by weight, preferably about 1 percent to about 20 percent, by weight, of said tetraarylboron compound. As is noted-hereinabove, the choice of solvent carriers for the sodium and lithium tetraarylborons is not limited other than that they be compatible and pharmaceutically acceptable, as herein defined.
There are a variety of solvents which can be used herein to prepare solutions of the compounds of formula (I) for antiperspirant use. For example, water can be used for this purpose. When water is employed as a solvent for the tetraarylboron compounds to provide aqueous antiperspirant formulations, it should first be carefully deionized by standard deionization techniques to render it substantially free of metal cations. Non-amine chelating agents can also be used to remove such interfering cations. Another procedure which can be used to advantage is to add to the solvent an excess of the sodium or lithium tetraarylboron compound over that desired in the composition, said excess being calculated to precipitate and remove the contaminating metal ions present in the water.
When organic solvents are used to prepare solutions of the compounds of formula (I) suitable for use as antiperspirants, the aforementioned problem concerning the interference by metal cations is small, since organic solvents characteristically contain little, if any, metallic cations. Organic solvents used herein can be distilled to remove substantially all such metallic residues.
As noted hereinabove, nearly all amines and aminecontaining materials precipitate the sodium and lithium tetraarylboron compounds as amine-boron complexes and are, hence, not useful herein as solvents.
Some of the solvents suitable for use with the tetraarylboron compounds of formula (I) to provide antiperspirant compositions in solution form include: alcohols, especially alcohols having from one to about 16 carbon atoms; esters, especially those liquid esters of lower organic acids and alcohols having from about one to about 16 carbon atoms; polyoxyalkylene materials, for example polyoxyethylene in the molecular weight range from about 50 to about 10,000. Non-limiting examples of compatible, pharmaceutically acceptable solvents suitable for use in preparing antiperspirant compositions containing sodium or lithium tetraarylboron compounds of formula (I) in solution include: ethyl alcohol, isopropyl alcohol, butanol, isobutanol, 2- ethyll-hexanol, hexadecanol, methyl propionate, ethyl formate, decyl formate, methyl decanoate, isopropyl myristate and the like. Especially preferred compatible, pharmaceutically acceptable carriers which are solvents for use herein in the preparation of antiperspirant compositions wherein the sodium or lithium tetraarylboron compound of formula (I) is dissolved are water, especially deionized water, ethyl alcohol, isopropyl alcohol, polyoxyethylene and mixtures thereof.
Alternatively, the sodium and lithium tetraarylboron compounds of formula (I) can be formulated in antiperspirant compositions wherein said tetraarylboron compound is not dissolved in the carrier but is merely suspended therein in particulate form. For example, a composition comprising greater than about 0.01 percent, by weight, preferably from about 1 percent to about 20 percent, by weight, of a particulate sodium or lithium tetraarylboron compound of formula (1) and a compatible, pharmaceutically acceptable solid or liquid carrier in which said boron compound is essentially insoluble provides an effective antiperspirant Composition. Suitable non-solubilizing carriers include such exemplary materials as: waxes, for instance the high molecular weight esters obtained from various plant and animal sources; oils, for example sunflower oil, turtle oil, minkoil, safflower oil, civet oil, and other oils commonly employed in cosmetic applications; high molecular weight alcoholic materials, for example sterols such as B-sitosterol and campesterol and materials such as cholesterol; lanolin and the commercially available alkylated and alkanolylated lanolins which are commonly employed in cosmetic formulations; higher molecular weight polyoxyalkylene materials which are semi-solid or waxy solids; and high molecular weight waxy hydrocarbons, e.g., petrolatum. Carboxyalkyl celluloses and high molecular weight polyoxyalkylene materials can also be used herein as gelling agents. Such materials are suitable herein, singly and in mixtures, both by virtue of their compatibility and their pharmaceutical acceptability. I
The hereinabove described non-solubilizing carrier materials useful herein fall within that class of compounds commonly referred to as skin emollients. As is "recognized in the art, such emollient materials are often employed in conjunction with many of the materials hereinabove referred to as solvents for the sodium and lithium tetraarylboron compounds. Such combinations of the solvent materials and emollient materials also provide carrier mixtures suitable for use herein in the formulation of antiperspirant compositions containing the sodium or lithium tetraarylboron compounds of formula (1).
Still another class of carriers which are suitably employed with the sodium and lithium tetraarylboron compounds include those halogenated, i.e., chlorinated, fluorinated and chloro-fluorinated, lower molecular weight hydrocarbons which are commercially used as propellants. Many of these materials have vapor pressures of 1 atmosphere, or greater, at temperatures of about 20C, and above, but ,are commonly li'quified under pressure and employed as propellants in aerosol cosmetic formulations. These liq'uified gases can be employed to propel antiperspirant solutions of the sodium or lithium tetraarylboron compound by mixing said solution with the liquified propellant gas under pressure. In an alternate mode, the undissolved, solid sodium or lithium tetraarylboron compound can be suspended in the pressurized liquified gas, itself. Commonly, antiperspirant compositions comprising liquified propellant gases and antiperspirant ingredients also contain one or more emoll'ients of the type hereinbefore noted. Such compositions comprising a dissolved or undissolved sodium or lithium tetraarylboron compound of formula (I), a liquified propellant gas and one or more of said emollient materials are also within the scope of this invention. Antiperspirant compositions comprising from about 0.1 percent to 10 percent, by weight, of an undissolved sodium or lithium tetraarylboron compound of formula (I) in combination with from about percent to percent by weight of liquified propellant gas, from about 2 percent to about 10 percent, by weight, of a compatible, pharmaceutically acceptable emollient as hereinabove disclosed and from about 0.1 percent to 2 percent, by weight, of a suspending agent capable of maintaining the particulate matter in a more-or-less stable suspension are preferred embodiments herein. Suspending agents such as fumed colloidal silica or oleophilic Bentonite clays can be employed herein in the manner well-known to those skilled in the art to help stabilize such aerosol antiperspirant compositions containing the antiperspirant compounds of formula (I).
From the foregoing, it can be seen that antiperspirant compositions comprising a sodium or lithium tetraarylboron compound of formula (I) in combination with all manner of pharmaceutically acceptable emollients, propellants, solvents and suspending agents, and mixtures thereof, which are substantially free from interfering metal cations and amines can be prepared. The sodium and lithium tetraarylboron antiperspirant compounds of formula (I) can therefore be employed in antiperspirant formulations such as sprays, sticks, rollons, aerosols and the like. All manner of additives commonly found in cosmetic formulations can be employed in the preparation of said compositions to provide more cosmetically acceptable products if such additives are substantially free from dissolved cations other than lithium or sodium cations and amines of the type hereinbefore defined.
The following examples are intended only to illustrate the preparation of the sodium and lithium tetraarylboron compounds of formula (I) which can be employed as antiperspirants in the manner'of this invention. The examples are not intended to be an ex haustive compilation of such reactions since it is wellknown to those skilled in the art that the reaction of a triarylboron compound with an appropriate aryl lithium or aryl sodium compound will provide all manner of such sodium and lithium tetraarylboron compounds. As hereinbefore noted, sodium tetraphenylboron, which is one of the most preferred compounds for use herein, is commercially available.
EXAMPLE I Preparation of Lithium tetra-(o-Tolyl)boron An ethereal solution of o-tolylmagnesium bromide is prepared from one mole of o-tolyl bromide and 1.] moles of magnesium turnings in about 1.5 liters of anhydrous diethyl ether, in the manner Slough, et al., J. Chem. Soc., (1955) 108. A solution of 0.3 moles of boron trifluoride in diethyl ether (commercially available BF 'EL O) is added to the o-tolylmagnesium bromide Grignard solution and refluxed briefly. The resulting tri-o-tolylboron compound is recovered by vacuum distillation. A solution of o-tolyl lithium is prepared from lithium shot and o-tolyl bromide in diethyl ether according to the procedure of F. Hein, et al., Z. Anorg. Chem., 141, 161 (1924). The solution of o-tolyl lithium is admixed with an ethereal solution of the tri-o-tolylboron (40C, 24 hours) and the ether removed by vacuum distillation to provide crystals of lithium tetra- (o-tolyl)boron.
In the above process, the o-tolyl lithium is replaced by four equivalents o-tolyl sodium, prepared in analogous fashion using sodium metal, and the BF Et- O is replaced by one equivalent of NaBF and the sodium tetra-(o-tolyl)boron compound is thereby secured.
In the above process, the o-tolylmagnesium bromide is replaced by an equivalent amount of p-methoxyphenyl-magnesium bromide prepared by the reaction of p-methoxyphenyl bromide with magnesium turnings in diethyl ether. The resulting tri-(p-methoxyphenyl)boron is allowed to react with p-methoxyphenyl sodium 1:1 mole basis) in diethyl ether and the resulting sodium tetra-(p-methoxy-phenyl)boron is recovered by crystallization. Sodium tetra-(p-methlbenzoate)boron is prepared in like fashion by reacting BF3-Et O with the Grignard reagent prepared from the methyl ester of p-bromobenzoic acid and subsequently reacting the triarylboron compound with the methyl ester of p-carboxyphenyl sodium.
According to the procedure of Razuvael, et al., CR. Acad. Sci. U.R.S.S., 91, 86 (1953), a-naphthyltriphenylboron is prepared by allowing a 0.321 molar mixture of boron trifluoride etherate and phenyl magnesium bromide to react and then mixing the resulting triphenylboron with a-naphthyl lithium, prepared from a-bromonaphthalene and lithium wire. In like fashion, are prepared lithium triphenyl-p-tolyboron from triphenylboron and p-tolyl lithium, and lithium phenyltri-a-naphthylboron from tri-a-naphthylmagnesium bromide, boron trifluoride etherate and phenyl lithium.
From the foregoing it can be seen that all manner of sodium and lithium tetraarylboron compounds of formula (I) can be prepared by reacting a triarylboron compound with the desired aryllithium or arylsodium compound. Of the sodium and lithium tetraarylboron compounds suitable herein, those compounds wherein the aryl group is phenyl, carboxyphenyl, i.e., benzoic acid derivatives, alkyl esters of benzoic acid, or alkoxyphenyl groups are most preferred. Substituent groups on the phenyl ring can be at any of the ortho, para or meta positions with equivalent antiperspirant results. Especially preferred are those alkoxyl and alkyl ester derivatives of the tetraphenyl boron compounds having lower alkyl groups, i.e., those containing from about one to l0, more preferably one to six, carbon atoms. When the substituent on the phenyl ring is carboxyl, i.e., benzoic acid, the sodium or lithium salt form of the acid is also suitable herein. Examples of such preferred antiperspirants include compounds of formula (I) wherein substituent R is a lower alkyl ester of benzoic acid, especially the ortho-, metaand para-methylbenzoates, and the lower alkoxyphenyl derivatives especially ortho-, paraand meta-methoxyphenyl groups; the sodium salts of these are preferred.
The following are examples of some antiperspirant compositions employing sodium or lithium tetraarylboron compounds of formula (I) as the antiperspiration ingredient in the manner of this invention.
EXAMPLE ll Antiperspirant Powder Percent By Weight Ingredient 15 Sodium tetraphenylboron (powder; having an average particle size below about 37 microns) X5 Talc Application of the above composition to the human skin in amounts of about 1.0 microgram/mm gives good antiperspirant results.
In the above composition, the sodium tetraphenyl- Dichloroditluoromethane and trifluoroethane. :20 weight mixture.
Application of about 0.001 g/mm of the above composition to the skin gives good antiperspirant results.
In the above composition the sodium tetraphenylboron is replaced by an equivalent amount of lithium tetra-(p-butoxyphenyl)boron, sodium tetra-(para-t-butoxyphenyl)boron sodium tetra-(o-tolyl)boron, sodium tetra-(p-methylbenzoate)boron, sodium tetra-(pmethoxyphenyl)boron, sodium tetra-(p-carboxy-phenyl)boron and sodium tetra-(o-decyloxyphenyl)boron, respectively, and equivalent antiperspirant compositions are secured.
EXAMPLE IV Aerosol Solution Antiperspirant Percent By Weight Ingredient 20 Sodium tetraphenylboron 20 Ethyl alcohol isopropyl alcohol (2:1 volume mixture) 0. l Hexchlorophene 0.7 Perfume Balance Propellant* Dichlorodifluoromethane and trifuloroethane, 60:40 weight mixture.
Application of about 1 g/24 cm of the above composition to the skin gives good antiperspirant results.
In the above composition the sodium tetraphenylboron is replaced by an equivalent amount of sodium tetra-(p-methylbenzoate)boron, sodium tetra-(mmethylbenzoate)boron and sodium tetra-(o-methylbenzoate)boron, respectively, and equivalent antiperspirant compositions are secured.
EXAMPLE V Antiperspirant Stick Percent By Weight Ingredient l Sodium tetraphenylboron Polyoxyethylene gel 0.2 Perfume Balance Lanolin Application of about g/24 cm of the above composition to the skin gives good antiperspirant results.
In the above composition the sodium tetraphenylboron is replaced by an equivalent amount of lithium tetra-(o-ethoxyphenyl)boron, lithium tetra-(a-carboxyl)boron, respectively, and equivalent antiperspirant compositions are secured.
EXAMPLE VI Roll-on Antiperspirant Percent By Weight Ingredient 5 Sodium tetraphenylboron 50 Ethyl alcohol 20 Lanolin 20 Isopro yl myristate 0.1 Hexch orophene 0.5 Perfume Balance lsopropyl alcohol Application of about 0.01 g/cm of the above composition to the skin gives good antiperspirant results.
In the above composition the sodium tetraphenylboron is replaced by an equivalent amount of sodium tetra-(p-carboxyphenyl)boron sodium salt form, and sodium tetra-(o-carboxyphenyl)boron, lithium salt form, and equivalent antiperspirant compositions are secured.
The following tests were used to assess the antiperspirant efficacy of sodium tetraphenylboron. In each test the sodium tetraphenylboron was used as an aqueous solution in deionized water.
TEST 1 A 5% (wt.) solution of sodium tetraphenylboron was prepared by dissolving 0.5 g. of sodium tetraphenylboron (commercial material) in 9.5 g. of deionized water. In the test procedure, 1 ml. of the above solution was applied to a l in. square cotton patch which was affixed to the inner forearm of test subjects for one hour. Following this patching procedure, the volunteers were placed in a hot room at 110F and 47 percent relative humidity for a few minutes and the perspiration inhibition on the test portion of the arm was visually estimated using a phenolphthalein test cream by comparing the patched portion with the surrounding forearm skin. The results on three test subjects were as follows:
Subject 2 Subject 3 100% inhibition 90 inhibition Aluminum chlorhydrate, the most commonly used antiperspirant compound, generally gives perspiration inhibition scores of 50 percent to percent in similar tests.
The test procedure was repeated in the same fashion using a solution com rising 1.0 g. of sodium tetraphenylboron m 9.0 g. of eionized water with the following results:
Sub'ect 1 Subject 2 inhibition Subject 3 inhibition 100% inhibition In the above tests, no evidence of skin irritation was noted.
TEST 2 In the following test, the overall antiperspirant efficacy of sodium tetraphenylboron was assessed over a five day test period and compared with the antiperspirant effectiveness of aluminum chlorhydrate, a commonly used antiperspirant, on the same test subjects and under the same test each In this test, the historical perspiration flow from three volunteers was assessed by daily perspiration collections using cotton pads at a temperature of 1 10F and 47 percent relative humidity under conditions wherein the subject exercised for five minutes and then walked for five minutes during axillary perspiration collection; the collected perspiration was weighed to establish each volunteer's normal (historical) perspiration flow under these conditions. Following the establishment of the historical average for each subject, 1 gram of a 10% (wt.) solution of sodium tetraphenylboron in deionized water (prepared fresh eacy day) was applied to the right axilla of each subject for five consecutive days. A freshly prepared 10% (wt.) solution of aluminum chlorhydrate was applied in the same fashion to the left axilla. After five days of such application the perspiration flow rate of the subjects was tested, again at F and 47 percent relative humidity using the exercise-rest procedure noted above, and the perspiration flow rate compared to the historical perspiration flow rate of the individual. On the average of the three individuals tested, the 10 percent sodium tetraphenylboron caused a 35 percent decrease in the absolute quantity of perspiration as compared to a 19 percent decrease for the 10 percent aluminum chlorhydrate.
From the foregoing, it may be seen that the tetraarylboron compounds of formula (I), especially sodium tetraphenyl boron, provide superior antiperspirant activity when applied to human skin.
What is claimed is:
l. A method for inhibiting perspiration comprising applying a perspiration inhibiting effective amount of sodium tetraphenylboron to human skin.
2. A process according to claim 1 wherein the sodium tetraphenylboron is applied to the skin in an amount of at least about 1.0 micrograms per mm of skin.