Composition and method for the treatment of acne

Compositions containing organic peroxides are effective for the treatment of acne. Decomposition of the organic peroxide during storage is prevented by the incorporation of glycerol which is sufficiently effective so that decomposition is prevented even in those peroxides which are so unstable as to be explosive.

BACKGROUND OF THE INVENTION 
Acne vulgaris affects virtually all youngsters beginning at the age of 
about 13 years and continuing through the age of 23 years. In females the 
onset may occur at an age as early as 10 or later on in the 20's or 30's. 
As is evident from all of the media, this affliction is sufficiently 
frequent and the mental suffering, particularly, sufficiently severe so 
that many companies vie for the resultant market for appropriate 
medications. The number of anti-acne products sold over the counter and by 
prescription is enormous. 
Many compounds and compositions have been tested and prescribed for the 
disease and a number have been fairly effective, but, as yet, there has 
been no complete cure for acne. 
Therapy is extremely important since if acne is left untreated, cysts form 
which result in permanent pitting and disfiguring scarring. Moreover, 
since acne is a disease primarily of adolescence, when the sufferers are 
most uncertain of themselves in their new roles, the attendant stigma, 
both supposed and real, can be the source of severe psychological trauma. 
There appears to be no doubt but that the increased flow of hormones at the 
onset of and during adolescence is the primary etiologic agent, since 
these hormones increase the size of the sebaceous glands and increase the 
secretion produced by these glands. However, no correlation has been found 
between the amount of endogenous serum hormone levels and the severity of 
acne in the individual. 
The sebaceous glands which are present in the dermal layer of the skin 
produce sebum. These glands are concentrated particularly on the face, 
upper torso including both the chest and back, and on the scalp. 
Susceptibility to acne is usually greatest on the nose and on the face. 
As the sebum is produced it normally flows slowly onto the surface of the 
skin. When the ducts through which the sebum flows are blocked, the sebum 
cannot reach the surface of the skin so that pressure builds up in the 
ducts and the ductal wall ruptures, allowing the sebum to seep into the 
skin's dermal layers, causing inflammation. Applying pressure to the 
inflamed area spreads the sebum into the dermal tissue and spreads the 
inflammation over a wider area. 
The sebum is broken down by microorganisms which are normally present in 
and on the skin, the principal microorganism being C. acnes. This 
microorganism produces lipase enzymes which hydrolyze the triglycerides of 
the sebum, forming the free fatty acids which are responsible for the 
externally visible comedones. The plug formed when a sebaceous duct is 
blocked is called a "comedo". The comedo itself is a noninflammatory 
lesion consisting of lipid and keratin. The lesions may initiate as 
papules which in turn may evolve into pustules. However, the lesions may 
also be in the form of deeper nodules which enlarge into cysts. 
Diet was originally considered to be one of the principal factors 
responsible for acne, the other being a lack of complete cleanliness. 
Chocolate was frequently considered the major villain, but recent studies 
have shown that neither strict prohibition of suspected foods nor strict 
hygienic cleansing of the skin gives the desired elimination of acne. 
With the recognition of the fact that bacteria were responsible, treatment 
with antibiotics became popular, tetracycline being the drug of choice. 
However, the degree of improvement produced by the use of any of the 
antibiotics was so small that it was frequently unrecognizable. Treatment 
with sulphur lotions has a long history but, again, this material by 
itself failed to produce substantial improvement of the condition. 
Complicating this situation has been the fact that young women, 
particularly, resort to the use of cosmetics, many of which, despite 
claims to the contrary, proved to be severely comedogenic. Increase in the 
severity of the acne caused by cosmetics then leads to the use of similar 
materials as covering agents, further exacerbating the condition. 
A. M. Kligman in work carried out in cooperation with James E. Fulton, Jr. 
discovered that peeling of the skin induced by topical application of 
Vitamin A acid, also called retinoic acid was beneficial in the treatment 
of acne, and U.S. Pat. No. 3,729,568 issued to Kligman in 1973. 
Approximately simultaneously, the effect of topical application of benzoyl 
peroxide was also investigated and it was found that the treatment was 
relatively effective. U.S. Pat. No. 3,535,422 entitled "Stable Benzoyl 
Peroxide Composition" issued to Richard M. Cox and Leonard R. Clufo in 
1970. 
The effectiveness of benzoyl peroxide in the treatment of acne proved to be 
a function of the stability of the composition applied to the affected 
region. Cox et al taught that dispersing benzoyl peroxide in a fluid 
medium consisting only of water and organic emollients produced a 
substantially inert, stable composition. This stability is necessary if 
the product is to have a reasonable shelf-life, either in the pharmacy or 
in the family medicine chest. However, as will be shown below, benzoyl 
peroxide compositions prepared in accordance with any of the formulations 
heretofore available decompose rapidly during storage. Decomposition of 
the benzoyl peroxide when in contact with the skin is desirable since it 
is the oxidizing effect of the free radicals produced on decomposition 
which provides the desired effect. However, decomposition during storage 
severely reduces the effectiveness of a composition which is prepared so 
that it has initially the optimum concentration. 
As is evident, then, a composition in which the benzoyl peroxide is stable 
during storage and yet decomposes readily on contact with the skin would 
be highly desirable, as would be a method of treatment based on such a 
composition. Moreover, other organic peroxides have also been found to be 
effective for the treatment of acne and some of these are even more 
unstable during storage than is benzoyl peroxide. It would also be 
desirable that a means of contributing stability of such peroxides during 
storage be provided. 
SUMMARY OF THE INVENTION 
A medium for the dispersion of organic peroxides contains glycerol as an 
inhibitor against the decomposition of such peroxides during storage 
between the time of dispersing the peroxide in the medium to form a 
composition and the time of use of said composition. For certain uses it 
is also desirable that a gelling agent be included in the composition, the 
preferred form of the composition being a soft gel or grease. The 
viscosity of the composition should be such that it can be applied with 
the finger to form a thin film on the skin which can readily be wiped off 
after remaining in contact with the skin for a prescribed period. The 
preferred gelling agent is Carbopol 940, a carboxyvinyl polymer having a 
molecular weight of about 4,000,000 manufactured by B. F. Goodrich Company 
said resin being highly ionic and slightly acidic and soluble. When this 
gelling agent is used the pH of the composition should be adjusted with 
alkali to about 4. Compositions containing a peroxide and glycerol as the 
stabilizer may also take the form of lotions or soaps, such compositions 
being useful as surgical scrubs. 
The content of organic peroxide in the composition may range from 10 to 300 
grams per liter of composition. The preferred range of concentrations, the 
preference being based on effectiveness, is from about 100 grams to 200 
grams per liter of composition. The glycerol content may range from 50 to 
500 ml per liter. With the glycerol may be combined up to 200 grams of 
propylene glycol per liter. 
Sulphur may also be incorporated with advantage in the organic peroxide 
composition, the quantity of sulphur used being from 10 to 300 grams per 
liter of composition. 
A preferred method of treatment is the application of the composition to 
the affected area once per day with the removal of the composition from 
the skin when a feeling of irritation is noted. Application of retinoic 
acid to the skin between applications of the organic peroxide composition 
may also prove advantageous in certain cases. 
Certain of the peroxides are so unstable that they can be stored and 
shipped only under refrigeration. Dispersing of these peroxides in 
glycerol yields a composition in which the peroxide is sufficiently stable 
so that the composition can be shipped. 
Accordingly, an object of the present invention is a composition suitable 
for the treatment of acne of all grades of severity, the composition 
containing an organic peroxide and an inhibitor against decomposition of 
said peroxide, said composition being useable as such or modifiable to 
form a lotion or a soap effective for surgical scrub. 
A further object of the present invention is a composition suitable for the 
treatment of acne, said composition including an organic peroxide, an 
inhibitor against the decomposition of the peroxide and sulphur. 
A significant object of the present invention is a highly effective method 
of treating acne. 
An important object of the present invention is a method of preparing a 
composition for the treatment of acne where the composition includes an 
organic peroxide and an inhibitor for stabilizing said organic peroxide. 
Still another object of the present invention is a composition including an 
organic peroxide and an inhibitor against decomposition of said peroxide, 
wherein said composition is sufficiently stable to permit shipment of 
same. 
Still other objects and advantages of the invention will in part be obvious 
and will in part be apparent from the specification. 
The invention accordingly comprises the composition possessing the 
features, properties and the relation of constituents which are 
exemplified in the following detailed disclosure, the several steps and 
the relation of one or more of such steps with respect to each of the 
others in the manufacture of said composition, and the several steps and 
the relation of one or more of such steps with respect to each of the 
others in the method of use of said composition, all of which are 
exemplified in the following detailed disclosure, and the scope of the 
invention will be indicated in the claims.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Benzoyl peroxide, used for the treatment of acne, was originally viewed as 
a skin irritant causing peeling in much the same way as does retinoic 
acid. However, I have found that when areas affected with acne are treated 
in accordance with the present invention both the count of C. acnes and 
free fatty acid in the sebum are reduced. Since it is the bacteria which 
are responsible for the production of free fatty acid it is evident that 
benzoyl peroxide as well as other organic peroxides, both alkyl and acyl, 
when applied as taught herein, reduce the severity of or eliminate once by 
sterilization of the pores. 
The analysis of sebum was carried out in accordance with the procedure 
described in the paper entitled "Sebum: Analysis by Infrared Spectroscopy" 
by Arthur S. Anderson and James E. Fulton and published in the Journal of 
Investigative Dermatology Vol. 60, No. 3 pages 115-120. 
FIG. 1 shows the relationship between the content of free fatty acid in 
sebum and the concentration of C. acnes in skin. This Figure is taken from 
the paper entitled "Studies on the Mechanism of Action of Topical Benzoyl 
Peroxide and Vitamin A Acid in Acne Vulgaris" by James E. Fulton, Jr., A 
FarzadBakshandeh and Sara Bradley and published in the Journal of 
Cutaneous Pathology 1974, volume 1, pages 191-200. The abcissa in FIG. 1 
is actually the rate of production of C. acnes per square centimeter of 
skin and the ordinate is the ratio of free fatty acid, FFA to fatty esters 
in the sebum, FE. Since C. acnes is primarily responsible for the lesions 
on the skin, it can be seen that the ratio FFA/FE correlates directly with 
the concentration of C. acnes of the skin. Further, since topical 
application of benzoyl peroxide and other organic peroxides quickly 
reduces the concentration of the bacteria, it is therefore evident that 
the organic peroxides function in the alleviation and cure of acne by 
sterilization of the skin. 
I have found that compositions prepared as described below are effective in 
the alleviation and cure of acne. 
A vehicle is prepared which contains an inhibitor against the decomposition 
of organic peroxide, the inhibitor being glycerol. For the preparation of 
one liter of a composition including dispersed organic peroxide, the 
quantities of ingredients in the vehicle are 50 to 500 ml of inhibitor, 0 
to 200 ml of propylene glycol, 1,2-propanediol being the preferred 
propylene glycol, and water in an amount needed to bring the total 
quantity of the composition up to one liter. 
The base to be combined with the above vehicle to prepare a liter of 
dispersion of organic peroxide may contain from 10 to 300 grams of organic 
peroxide, preferably benzoyl peroxide. 
Preferably, the dispersion is thickened to the consistency of a soft gel or 
grease. Appropriate thickeners are finely divided silica, also known as 
"Fumed Silica", magnesium aluminum silicate and Carbopol 940, manufactured 
by B. F. Goodrich. Carbopol 940 is a carboxyvinyl polymer having a 
molecular weight of about 4,000,000. The base should also contain 
sufficient alkali to bring the pH of the composition to a value between 
3.5 and 5.0, the range from 3.5 to 4.0 being preferred. Where benzoyl 
peroxide is used as the organic peroxide, this is added in the form of 
pellets, the commercial preparation containing 78% benzoyl peroxide and 
22% water. Following is a sample composition which may be regarded as the 
basic composition from which others are prepared by adjustment of the 
quantities and nature of ingredients. 
______________________________________ 
Concen- 
tration 
Range 
______________________________________ 
I. VEHICLE: 
H.sub.2 O 600 ml. q.s. 
Glycerol 200 ml. 50-500 
Propylene Glycol 
(1,2-propanediol) 
50 ml. 0-200 
850 ml. 
II. BASE: 78% Benzoyl Peroxide 
128 gm. 1-30% 
Carbopol 940 7 gm. .5-2% 
1N NaOH 5 gm. 1 ml to 20 ml 
Makes 1 liter. 
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The benzoyl peroxide is added to 600 ml of the vehicle in a high-shear 
blender, and agitated for several minutes until dispersion is complete and 
the product is uniform. The Carbopol 940 is dissolved in 200 ml of the 
vehicle and this solution is then added to the benzoyl peroxide 
dispersion. Agitation is continued until the lotion is smooth, after which 
the NaOH in the form of a 1N solution is added, blending being continued 
until the resultant soft gel is homogenous. The gel can be packaged in 
plastic tubing, or in resin-lined aluminum tubing. Due to its acidic 
nature it cannot be packaged in unlined metallic tubing. 
As will be evident, the quantities given above can be increased and batches 
of any desired size can be manufactured according to the procedure 
described. 
Additional ingredients may also be incorporated in the composition. 
Sulphur, particularly, has been found advantageous in certain cases. The 
quantity of sulphur added may be up to about 300 grams per liter of 
dispersion, about 10 grams per liter being the minimum effective quantity. 
Iron oxide, or other pigments may be added to give color to the 
composition. Alternatively, a composition may be prepared similar to that 
given above except for the content of organic peroxide. Instead, iron 
oxide or other pigment is added to give a desired color. Such a 
composition is termed a "cover-up". It may be used in combination with the 
peroxide composition to disguise the presence of the peroxide composition 
on the skin. The advantage of the composition combining stabilized 
peroxide with colorant is that it serves as a cosmetic which can be kept 
on the skin throughout the day, the peroxide content being adjusted to 
correspond to the tolerance of the patient. 
It is believed that the action of the glycerol is to reduce the solubility 
of the peroxide in the vehicle. As a result of the fact that the 
solubility of the peroxide is reduced, the rate of decomposition of the 
peroxide in the composition during storage is greatly decreased. Studies 
have been carried out comparing the rates of decomposition of benzoyl 
peroxide in various solvents. The results are shown in FIG. 2, the tests 
having been carried out at 45.degree. C. to accelerate the decomposition. 
As can be seen at the end of 4 weeks, virtually all of the benzoyl 
peroxide in a composition within the scope of the present invention and 
manufactured by AHC Pharmaceutical Inc. remains intact. In contrast, only 
about 7% of the benzoyl peroxide remains after this period of time when 
the benzoyl peroxide is mixed with ethanol. Propylene glycol alone, as the 
solvent, decomposes the benzoyl peroxide even more rapidly for the first 
two weeks, after which the decomposition substantially stops, about 27% of 
the original benzoyl peroxide remaining. The rate of decomposition is 
substantially slower in water, about 52% of the benzoyl peroxide remaining 
after 4 weeks at 45.degree. C. Brij 30, referred to in FIG. 2, is the 
trade-name for polyoxyethylene-4-lauryl ether. 
Since the organic peroxide appears to be of limited solubility in the 
vehicle taught herein, the resultant composition may be referred to as a 
"dispersion". However, it is to be recognized that the invention is not 
limited to the mechanism proposed herein or by the terminology used, since 
some of the organic peroxide is undoubtedly soluble in the vehicle. The 
use of the term "dispersion" is followed because of convenience and is not 
intended to indicate the state of the organic peroxide in the vehicle. 
That the combination of an organic peroxide with an inhibitor such as 
glycerol has practical effectiveness from the standpoint of stability can 
be seen from FIG. 3 which provides the results of storage tests at 
45.degree. C. carried out on a number of commercial formulations all of 
which initially have 10% of benzoyl peroxide therein. Compared with these 
commercial preparations is a formulation prepared in accordance with the 
present invention, and indicated as AHC Formulation 10. As can be seen 
from FIG. 3, all of the commercial preparations show serious losses of 
active benzoyl peroxide after 6 weeks of storage at 45.degree. C. whereas 
the composition containing 10% of benzoyl peroxide and formulated in 
accordance with the present invention retains about 98% of the initial 
benzoyl peroxide after the 6 weeks storage period. 
A substantial number of organic peroxides are presently available, a 
particularly desirable organic peroxide being the succinyl peroxide. 
Succinic acid, while somewhat less effective than benzoyl peroxide in the 
treatment of acne, has a major advantge in that the small percentage of 
individuals who are allergic to benzoyl peroxide are not similarly 
allergic to succinic acid. The reason that benzoyl peroxide may be 
allergenic is that the benzoyl radical formed in a hapten, haptens being 
substances which attach to a protein molecule and form an antigen. 
However, succinic acid is a normal constituent of the body in various 
biochemical processes and specifically in those concerned with the 
production of energy. Consequently, the succinic acid radical which is 
formed is not a hapten and thus the danger of sensitization or allergenic 
reaction is completely avoided. Lauryl and cumyl peroxides have also been 
found to be effective though not as effective as benzoyl peroxide. 
Surfactants can be included in stabilized benzoyl peroxide compositions 
without impairing the stability thereof. Following is a composition which 
is a lotion, effective as a surgical scrub, and which is a modification of 
the basic composition presented above. 
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LOTION 
______________________________________ 
Distilled Water 550 ml 
Glycerol 200 ml 
Propylene glycol 100 ml 
Benzoyl Peroxide (78%) 32 gm 
Carbopol 940 15 gm 
Stepanol 40 gm 
Sodium Lauryl Sulfate 40 gm 
Sodium Hydroxide 3 N 20 gm 
______________________________________ 
Note: Stepanol is a sodium alkyl sulfate manufactured by Stepan Corp. of 
Illinois. 
The benzoyl peroxide content in the above lotion formulation is 2.5%. As is 
evident, the concentration of peroxide and of the other components can be 
varied, as can the peroxide used, in ways apparent to those skilled in the 
art. 
Benzoyl peroxide, stabilized with glycerol may also be added to a 
conventional soap to provide benefits similar to those which accrue from 
the use of the compositions already taught. More particularly, a soap 
containing up to about 10% of a peroxide and containing glycerol in a 
ratio to the content of said peroxide similar to the ratios in the 
compositions taught above is an effective surgical scrub. Benzoyl peroxide 
is the preferred peroxide because of its relatively low cost and high 
effectiveness. Where compounds which may react with an organic peroxide 
are present in the soap stock to be combined with peroxide and glycerol, 
such compounds should be removed as by conventional means prior to 
formulation. 
A formulation suitable for a surgical scrub soap contains about 1% to about 
20% by weight of an organic peroxide, preferably benzoyl peroxide and 
sufficient glycerol to stabilize the peroxide. Propylene glycol may be 
incorporated in the soap if desired, as may conventional soap builders. 
The number of gelling agents which can be used is substantial, virtually 
any water-soluble polymer of sufficiently high molecular weight being 
appropriate. Carboxymethyl cellulose has been tested and found to be quite 
effective. Magnesium aluminum silicate and fine silica as previously noted 
can also gel the solution. However, the quantity of fumed silica necessary 
to obtain the same increase in viscosity provided by a given quantity of 
Carbopol 940 is about 10 times as great. 
Therapy with benzoyl peroxide is preferably commenced slowly; for example 
the dispersion should be allowed to remain on the skin or 3 to 4 hours 
daily. The initial burning sensation subsides rapidly after the first few 
weeks and exposure time can be increased. Where the patient is 
sufficiently sensitive so that irritation is excessive to the point where 
it may be termed "toxic", the condition is rapidly reversible within a day 
or two after interruption of treatment. Therapy can then recommence. Over 
3-4 weeks, the skin becomes hardened and accommodated to the treatment. As 
the patient becomes more accustomed to the use of the peroxide, the 
concentration and frequency of application may be gradually increased to 
the level required to maintain control. Although concentrations as high as 
30% in benzoyl peroxide and 30% in sulphur may be utilized, the maximum 
concentration is preferably 20% for benzoyl peroxide and 10% for sulphur. 
Tests have shown that the addition of sulphur in this concentration to 
benzoyl peroxide definitely increases the efficacy of the composition. 
In clinical studies, improvement is readily ascertained from the dramatic 
change in the total lesion count. In carrying out tests and evaluating the 
results of same, the lesions are graded by arbitrary standards from grades 
I through IV with grade IV being the most severe. 
TABLE I 
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TOTAL LESION COUNT AT 
TWO WEEK INTERVALS DURING TREATMENT 
FIRST CLINICAL STUDY 
2 4 6 8 
Group & Initial Week Week Week Week 
Medication Visit Visit Visit Visit Visit 
______________________________________ 
Acne, Grade I & II 
25.3 15.5* 15.0* 9.2 8.8 
Benzoyl Peroxide 
(22) (22) (16) (5) (9) 
10% 
21.3 10.5* 9.1* 15.2 9.0 
(20) (20) (10) (6) (2) 
Acne, Grade III & IV 
38.7 23.5* 17.8* 14.9* 14.1* 
Benzoyl Peroxide 
(180) (180) (133) (78) (60) 
20% + Sulfur 10% 
______________________________________ 
* = p&lt;0.05 
() = number of patients in each group 
Table I shows the results of a clinical study in which patients with acne 
of grades I and II were treated with a gel (dispersion) containing 10% 
benzoyl peroxide and patients with grades III and IV acne were treated 
with a gel (dispersion) containing 20% of benzoyl peroxide and 10% of 
sulphur. As is evident, the number of lesions decreased substantially 
during the 8-week period for the groups of patients. In fact, for the 
patients with acne of grades I and II, the benzoyl peroxide at a level of 
10% produced significant improvement within 2 weeks, the improvement 
progressing to a controlled condition at the end of the period. A 
significant marked decrease was also demonstrated for the group having 
grades III and IV acne which was treated with 20% benzoyl peroxide and 10% 
sulphur dispersion. 
In a second clinical study utilizing a more confined population similar 
results were obtained with a gel containing 10% benzoyl peroxide and 5% 
sulphur. The results are summarized in Table II. 
TABLE II 
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TOTAL LESION COUNT AT 
TWO WEEK INTERVALS DURING TREATMENT 
SECOND CLINICAL STUDY 
2 4 6 8 
Group & Initial Week Week Week Week 
Medication Visit Visit Visit Visit Visit 
______________________________________ 
Acne, Grade I & II 
27.4 18.9* 18.0* 17.5* 16.3* 
10% Benzoyl Peroxide 
(48) (48) (29) (17) (11) 
Benzoyl Peroxide 
31.8 24.6* 28.4* 19.8* 8.0 
10% + Sulfur 5% 
(28) (28) (19) (10) (5) 
Acne, Grade III & IV 
28.2 18.8* 12.9* 12.8* 8.4* 
Benzoyl Peroxide 
(50) (50) (28) (19) (14) 
20% + Sulfur 10% 
______________________________________ 
* = p&lt;0.05 
() = number of patients in each group. 
In general, treatment with a gel containing 20% of benzoyl peroxide and 10% 
of sulphur shows the most consistent and dramatic reduction in lesion 
count. 
The treatment with organic peroxide dispersion can be supplemented with 
treatment with retinoic acid. Thus, if the organic peroxide gel is applied 
in the morning, then retinoic acid may be applied in the evening. The 
retinoic acid is preferably used at a concentration of about 0.001% to 
0.01% in a non-irritating vehicle. It should not be formulated in 
ethanolic solutions which are irritating to the skin when used in 
conjunction with a material which tends to remove layers of the skin. A 
suitable vehicle for the Vitamin A acid is a low-boiling ester such as 
ethyl acetate or a ketone such as acetone. An excellent response which is 
considered synergistic is to apply the retinoic acid solution to the skin 
and allow it to dry for about 10 minutes, after which benzoyl peroxide gel 
is applied directly over the Vitamin A acid. 
A number of the organic peroxides are known which are sufficiently unstable 
so that they must be refrigerated. Others are so unstable that they may 
explode. Obviously, both of these types of compounds present difficulties 
with respect to shipment and use. I have found that dispersion of these 
organic peroxides in glycerol solution renders these compounds 
sufficiently stable so that they may be shipped without refrigeration and 
without presenting the danger of explosion. 
A particular advantage of the compositions described herein for the 
treatment of acne and of the treatment mode described is that the course 
of treatment requires the presence of a physician only intermittently. In 
general, a nurse can readily be trained to discern the progress of the 
treatment and whether a condition has arisen which requires the skill of a 
physician. Consequently, the extended treatment involved in alleviation of 
acne is made substantially less expensive than would be the case were it 
necessary for each application of the medicament to be made under the 
observation of a physician. 
It will thus be seen that the objects set forth above, among those made 
apparent from the preceding description, are efficiently attained, and, 
since certain changes may be made in carrying out the method of 
manufacturing the various products and in the compositions set forth 
without departing from the spirit and scope of the invention, it is 
intended that all matter contained in the above description and shown in 
the accompanying drawings shall be interpreted as illustrative and not in 
a limiting sense. 
It is also to be understood that the following claims are intended to cover 
all of the generic and specific features of the invention herein 
described, and all statements of the scope of the invention which, as a 
matter of language, might be said to fall therebetween.