Stable hydroalcoholic compositions

Details Stable hydroalcoholic compositions Stable hydroalcoholic compositions

2001-12-10

2003-05-13

Krass, Frederick (Department: 1614)

Drug, bio-affecting and body treating compositions

Preparations characterized by special physical form

Biocides; animal or insect repellents or attractants

C424S401000, C514S945000, C510S132000, C252S367100

Reexamination Certificate

active

06562360

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to compositions useful as skin disinfectants, surgical hand preparations, patient skin preparations and antimicrobial hand lotions. More specifically the invention relates to stable hydroalcoholic compositions which are thickened using mixed emulsifier systems.
BACKGROUND OF THE INVENTION
Control of nosocomial infection and exposure to infectious disease is of paramount concern to doctors, nurses, and clinicians who work in hospitals and surgery centers. One of the most effective methods for controlling infection is regimented hand disinfection before and possibly after each patient contact and particularly before and after each surgical procedure. Hand disinfection is generally accomplished using antimicrobial soaps with water. These soaps are usually formulated to include either povidone-iodine (usually 7.5% by weight) or chlorhexidine gluconate (CHG) (usually 2 or 4% by weight) as the active antimicrobial agent. In addition, these formulated soaps may contain surfactants and possibly low levels of humectants such as glycerin.
Hand disinfection is also accomplished using presurgical scrub replacements. These are used instead of the soap and water scrub. Presurgical scrub replacements ideally achieve bacterial kill equal to or better than a traditional soap and water scrub and in a shorter period of time. Additionally, they maintain or improve the skin's natural barrier to microbial and chemical contamination while providing acceptable tactile properties. Examples of presurgical scrub replacements include hydroalcoholic gels which generally include high levels of either ethanol or isopropanol as the disinfecting agent and also include a thickener and optionally include a humectant (e.g. glycerin). To date, thickeners used in hydroalcoholic gels have been based on anionic polymers such as polyacrylic acid (sold under the tradename Carbopol by BF Goodrich Specialty Polymers and Chemicals Division of Cleveland, Ohio). U.S. Pat. No. 4,915,934 to Tomlinson discloses the use of CHG-containing antiseptic foams based on hydroalcoholic solvents, a fatty alcohol, and a surfactant. The surfactant is selected from the group of ethoxylated sorbitan alkylates, ethoxylated fatty alcohols, and ethoxylated nonyl phenols.
Formulating stable viscous hydroalcoholic emulsions is difficult for two reasons. First, addition of short chain alcohols (such as ethanol) to an aqueous system decreases the surface tension dramatically. For example, 40% by weight ethanol in water has a surface tension of approximately 31 dyne/cm compared to pure water which has a surface tension of about 72 dyne/cm at 20° C. A hydroalcoholic solution at 60% by weight ethanol has a dramatically decreased surface tension as compared to water. Such a composition has a surface tension of approximately 27 dyne/cm at 20° C. Second, many surfactants typically used in cosmetic emulsions become completely or partially soluble in hydroalcoholic systems.
In bulletin 51-0001-259 regarding skin care, Specialty Chemicals of ICI America of Wilmington, Del. stated that although ethanol can provide several benefits to skin care emulsions, formulators often avoid ethanol as it is difficult to prepare stable emulsions in its presence. In fact, the bulletin continued that ethanol is often used to break emulsions.
U.S. Pat. No. 4,956,170 to Lee discloses a hydroalcoholic skin moisturizing/conditioning antimicrobial gel. The gel comprises 60-75% ethanol and 0.4-2% of a polymeric thickening agent. The formulations also comprise polyethoxylated non-ionic surfactants/emulsifiers to stabilize the added emollient oils in addition to a fatty alcohol.
U.S. Pat. No. 5,167,950 to Lins discloses an antimicrobial aerosol mousse having a high alcohol content. The mousse comprises alcohol, water, a polymeric gelling agent and a surfactant system comprising a C16-C22 alcohol, aerosol propellant and a non-ionic polyethoxylated surfactant.
SUMMARY OF THE INVENTION
This invention provides compositions useful as products for skin disinfection such as presurgical hand preps, patient preps, and lotions. The preferred formulations of this invention, in general, have a very nice feel after both single and multiple applications. Additionally, preferred formulations maintain or improve the skin condition after multiple applications and no slimy or abnormal feeling is noticed during post application hand washing. When used as a presurgical scrub replacement, this invention achieves bacterial, fungal, and viral kill equal to or better than a traditional soap and water scrub in a shorter period of time while maintaining or improving the skin's natural barrier to microbial and chemical contaminants. The invention overcomes the shortcomings of past compositions by providing a viscous composition which includes a high concentration of a lower alcohol but does not require a polymeric thickener to make the composition viscous. Further, the composition has a cosmetically elegant feel and may be dispensed as a lotion or as a foam.
This invention provides a composition comprising a lower alcohol and water in a weight ratio of about 35:65 to 100:0, between at least 0.5% and 8.0% by weight thickener system comprised of at least two emulsifiers, each emulsifier present in at least 0.05% by weight wherein the emulsifiers are selected such that the composition free of auxiliary thickeners has a viscosity of at least 4,000 centipoise at 23 degrees C. and wherein each emulsifier is comprised of at least one hydrophobic group and at least one hydrophilic group, wherein: (i) the hydrophobic group is comprised of an alkyl group of at least 16 carbon atoms; an alkenyl group of at least 16 carbon atoms; or an aralkyl or an aralkenyl group of at least 20 carbon atoms; and (ii) the hydrophilic group of at least one emulsifier is comprised of an amide group having the structure —NHC(O)R′″ or —C(O)NHR′″ where R′″ is hydrogen or an alkyl group of 1-10 carbon atoms optionally substituted in available positions by N, O, and S atoms; an ester group of short chain alcohols or acids (e.g., L=—C(O)OR′ or —OC(O)R′ where R′ is C1-C4 branched or straight chain alkyl optionally substituted in available positions by hydroxyl groups); a polyglucoside group having 1-10 glucose units; a polyglycerol ester group having 1-15 glycerol units, a secondary amine group; a tertiary amine group; a quaternary amine group; an anionic group such as a sulfate, sulfonate, phosphate, phosphonate, or carboxylate group; or a zwitterionic group having the formula:
—N
+
(R″)
2
(CHQ)
x
L′
or
wherein each R″ is independently hydrogen or an alkyl group (having 1-5 carbon atoms) or alkenyl group (having 2-4 carbon atoms), which alkyl or alkenyl groups are optionally substituted with nitrogen, oxygen, or sulfur atoms, including alkyl or alkenyl carboxyl groups; Q is hydrogen or hydroxyl; x is 1 to 4; and L′ is CO
2
−
, —OP(O)(O
−
)(O
−
M
+
), —(O)P(OR′″)(O
−
M
+
) (where R′″ is hydrogen or an alkyl group of 1-10 carbon atoms optionally substituted in available positions by N, O, or S atoms), —SO
2
O, or —OSO
2
O
−
, where M
+
is a positively charged counterion present in a molar ratio necessary to achieve a net neutral charge on the emulsifier and is selected from the group of hydrogen, sodium, potassium, lithium, ammonium, calcium, magnesium, or N
+
R″
4
; as well as combinations of these groups; and (iii) the hydrophilic group of at least one emulsifier is comprised of an alcohol group; an ethylene oxide/propylene oxide copolymer group having 2-150 moles of ethylene oxide plus propylene oxide per mole of hydrophobe (“R”) and bonded to the hydrophobe through an ether or ester linkage, and optionally terminated by C1-C36 alkyl or C6 to C36 alkaryl ester; an ester or ether group of a polyhydric alcohol and their polyalkoxylated derivatives; an ester or ether of sorbitan or polyalkoxylated sorbitan group

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