WO2013030635A2

WO2013030635A2 - Compositions for extended periods of skin moisturization

Info

Publication number: WO2013030635A2
Application number: PCT/IB2012/001080
Authority: WO
Inventors: Avani MAINKAR; Agarwal NIDHI; Manisha KHARKAR; Sudhakar MHASKAR
Original assignee: Marico Ltd
Priority date: 2011-09-02
Filing date: 2012-06-05
Publication date: 2013-03-07
Also published as: TW201315487A; SA112330815B1; WO2013030635A3

Abstract

The invention relates to skin moisturising compositions comprising upto 30% of coconut oil as a single active and cosmetically acceptable excipients, water, and optionally sensory modifiers wherein the said compositions retain moisturizing for substantially extended periods. The excipients are emulsifiers, structurants and thickeners. The sensory modifiers are preferably included in the compositions containing coconut oil from 10-30%. The invention also discloses a process for the preparation of moisturising compositions comprising steps! preparing a water phase by mixing water and preservatives followed by addition of thickener with heating upto 70°C; preparing an oil phase by mixing coconut oil, emulsifiers and structurants with heating upto 70°C; adding the heated oil phase to heated water phase followed by homogenization at temperatures upto 50 °C; adding neutralizer followed by the optional addition of a sensory modifier with heating upto 50 °C.

Description

Compositions for extended periods of skin moisturization Field of the Invention

The invention relates to coconut oil containing compositions for moisturisation of the skin for extended periods.

Background and Prior art.

The climatic conditions in tropical countries, particularly in the Asian and African continent cause conditions of dry skin wherein the level of moisture falls below 10%, leading to extensive use of skin conditioning agents. The challenge lies in providing compositions the enable the retention of moisture in the skin for extended periods. If water is lost more rapid than it is received from the lower layers of the epidermis, the skin becomes dehydrated and loses flexibility. Moisturising skin to enabling the restoration of water in skin is addressed in three ways namely occlusion, humectancy and restoration of deficient materials to the skin. Petroleum based formulations have been most popular. Further traditional compositions also contain mineral oil or vegetable oils, actives like glycerine, propylene glycol, urea, NMFs or lipids like ceramides or amino acids like glycine. Moisturisation provided by such formulations either have relatively short retention periods, making frequent multiple applications of the product an essential feature or need a combination of multiple moisturizing agents to achieve the desired retention effects.

EP2051691 discloses skin treatment composition containing: a) 0. 1 to 10 % by weight of a mixture consisting of: a: 1) 10 to 80 % by weight of a mixture of at least two ceramides with the provison that at least one of these ceramides contains a long alkyl, alkenyl or acyl side chain with 20 to 26 carbon atoms and that less than 40 % by weight has a side chain larger than 26 carbon atoms; a:2) 10 to 45 % by weight of cholesterol; a:3) 10 to 45 % by weight of free fatty acids with C 12 to C30 alkyl-, alkenyl, alkadienyl, alkatrienyl or alkapolyenyl chains or combinations thereof; b) 0.5 to 10 % by weight of a nonionic emulsifier or a nonionic emulsifier mixture with a combined HLB value of 12 to 19; c) > 40 % by weight of water and optionally; d) 0.1 to 10 % by weight of consistency enhancers and optionally; e) auxiliaries and additives.

US patent no 5578312 describes a skin care system that incorporates mixture of water, dried herbs, leaves, fruits, roots and or flowers, plant extracts and oil with non irritating lipids, binders, surfactants, emulsifiers and preservatives.

US patent no 4235889 describes a pharmaceutical composition consisting of palm kernel oil, coconut oil, extract of Laurus nobilis and an emulsifier for the treatment of skin conditions like Psoriasis, Tinea and eczema. The composition have 30-50% by weight of coconut oil, 30-50% by weight of palm kernel oil, 5- 15 percent by weight of an extract of Laurus nobilis and 5- 15% by weight of an emulsifier.

US patent application no 2010/0021563 relates to natural and homeopathic compositions comprising coconut oil as an active agent and atleast one additional active agent having homeopathic, medicinal, pharmaceutical and cosmetic properties. It further describes composition containing 40-80% by weight of unrefined coconut oil, 20-60% of cosmetic grade shea butter, optionally containing other pharmaceutically or cosmetically acceptable adjuvants. Compositions described in prior art disclose compositions in which coconut oil has been used in fairly high quantities of in combination with other oils and agents to achieve moisturizing benefits. The use of high amounts of coconut oil makes the product sticky and sensorially unacceptable to consumers. We have surprisingly found that it is possible to achieve sensorially superior moisturing benefit over extended periods despite the use of relatively low levels of coconut oil singly in combination with excipients and without the use of additional moisturizing agents.

Summary of the invention

The main object of the invention is to provide coconut oil containing compositions for extended periods of skin moisturization. Another object of the invention is to provide such coconut oil containing compositions wherein the percentage of coconut oil does not exceed 30 % exhibiting the desired extended period of moisture retention by the skin.

Another object of the invention is to provide such compositions that are non sticky with high sensorial acceptability.

Another object of the invention is to provide the said compositions without the use of commonly used emollient oils such as liquid paraffin.

Another object of the invention is to provide compositions that provide superior moisturisation in a short time Another object of the invention is to provide the said compositions to retain moisture in the skin for extended periods thereby reducing the frequency of application.

Detailed Description of the invention The present composition comprise an emulsion with upto 30% of coconut oil as a single active, excipients like emulsifiers, surfactants, water and fragrance.

Compositions of the present invention are prepared by process comprising steps:

i) Preparing a water phase by mixing water and preservatives followed by addition of thickener with heating upto 70°C,

ii) Preparing an oil phase by mixing coconut oil, emulsifiers and structurants with heating upto 70°C,

iii) Adding the heated oil phase to heated water phase followed by homogenization at temperatures upto 50 °C

iv) Adding neutralizer followed by the optional addition of a sensory modifier with heating upto 50 °C. In a preferred embodiment the process comprises:

i) Preparing a water phase by mixing water and parabens followed by addition of carbomer with heating

ii) Preparing an oil phase by mixing coconut oil, GMS, cetyl alcohol, stearic acid with heating

iii) Adding the heated oil phase to heated water phase followed by homogenization iv) Adding neutralizer followed by the optional addition of a sensory modifier such as silicone with heating

The temperatures in step i) and ii) are upto 70°C where as the heating in step iv) is carried upto 50 °C

Emulsifiers in the compositions at 0.5 to 5.0% are selected from polyetheylene glycol stearyl ethers, addition products of ethylene oxide and/or propylene oxide, and linear fatty alcohols having 8 to 22 carbon atoms or fatty acids having 12 to 22 carbon atoms, glycerol mono- and diesters of saturated fatty acids having 6 to 22 carbon atoms and ethylene oxide addition products. Structurants in the composition at 0.1 to 10.0% are selected from fatty alcohols, stabilizing polymers and thickeners

The thickening agent is selected from carbomer, acrylic acid polymers which may be homopolymers, copolymers and cross-polymers, cross linked polyacrylic acid salts, cross linked acrylic copolymers, carboxymethyl cellulose, carboxy vinyl polymers, Hydroxy ethyl cellulose, Hydroxy propyl cellulose, methyl cellulose, Xanthan gum, Carrageenan, Alginic acid salts, Pectin , Gum Arabic, Gatch gum, Karaya gum, Tragacanth gum, Agar powder, Bentonite. The preferred thickeners are Carbomer, Cross linked acrylic coplymers and Xanthan gum. The distinct moisturizing benefits of the compositions of the present invention have been demonstrated vis-a-vis compositions containing liquid paraffin.

In compositions containing relatively higher levels of coconut oil, (about 20 to 30% ), sensory modifiers are preferably used. The sensory modifiers are selected from esters (e.g. Isopropyl Myristate, Isopropyl Palmitate, Heptyl undecylenate, Neopentyl glycol Dihetanoate), ester ethers such as fatty acid esters of ethoxylated fatty alcohols, Silicones (eg. Cyclomethicone, Dimethicone etc).

The present invention results in a sensorially superior product using coconut oil as a single moisturizing agent in fairly low quantities. These compositions enable the use of a single active to provide desired moisturizer levels and eliminates additional costs and unwarranted use of undesirable synthetic moisturizing actives.

The invention is illustrated by non-limiting examples.

Examples

Example 1 : Composition with 7% coconut oil

Example 2 :Composition with 3% coconut oil

Example 3: Composition with liquid paraffin.

Triethanolamine 0.4

Simethicone 2

Phenoxyethanol 0. 1

Perfume 0.5

The compositions described above were tested on healthy human volunteers to access the extended skin moisture retention. Healthy human volunteers with visibly dry skin were recruited for the tests. Volunteers were made to wash their arms with surfactant solution and acclimatized in a temperature and humidity controlled chamber for 30 minutes. Trans-epidermal water loss (TEWL) was used as an indicator of any disruption in the barrier properties of the skin. Higher the TEWL, more is the compromise in the barrier properties causing dryness of the skin.

In phase 1 of the test protocol, TEWL was measured at the start of the test ("time 0") for each volunteer. This was taken as the baseline. Then a specified amount of the formulation 1 and formulation 2 was applied on one forearm of each volunteer. Formulation 3 was applied on the other forearm of each volunteer. The applications were repeated twice daily for 4 days. At the end of 4 days the TEWL was measured once again.

In phase 2 of the test protocol no product application was done and TEWL was measured after 7 days.

The % reduction in TEWL over baseline was calculated.

The results of the 3 formulations in examples 1 -3 are given in Table 1.

Table 1

% reduction in TEWL

Ex. 1 Ex. 2 Ex. 3

Day 4 65 21 12

Day 7 33 18 0 These results indicate that the maximum moisturizing benefit is obtained from the compositions with coconut oil. This benefit is also sustained for a longer time as compared to mineral oil (example 3) which is the most commonly used emollient.

Moisturizers have been thought to induce only a transient moistening effect of the skin surface. However, effective moisturizers produce changes even in the deep layers of the stratum corneum as well as in the superficial layers. Their repeated application on the skin produces an enhancement of skin surface hydration state that lasts for several days after cessation of the treatment, depending on their efficacy.

In another study, initial hydration level was measured at the start of the test ("day 0") for each volunteer using Comeometer. This was taken as the baseline. Then a specified amount of compositions containing different levels of coconut oil was applied at different locations of one forearm of each volunteer whereas formulations containing different levels of mineral oil were applied at corresponding locations on the other forearm of the same volunteer. The applications were repeated twice daily for 10 days. At the end of the 10^th day, hydration was again measured.

The % increase in hydration over baseline was monitored. The results are as follows:

Application of the compositions was stopped after 10 days and hydration was again measured on the 14^th, 16^th and 20^th day to monitor the level of hydration after cessation of the application.

The results are as follows:

These results indicate that higher moisturizing benefit is obtained from coconut oil containing compositions and this benefit is also sustained for a longer period as compared to applications of compositions containing the same dosage of mineral oil.

The table below summarises the results for compositions containing various quantities of coconut oil.

For compositions containing upto 10% coconut oil addition of sensory modifiers is optional . For compositions containing 10-30% of coconut oil addition of sensory modifier is preferable to obtain a sensorially acceptable product.

Claims

Skin moisturising compositions comprising upto 30% of coconut oil as a single active and cosmetically acceptable excipients, water, and optionally sensory modifiers wherein the said compositions retain moisturizing for substantially extended periods. Skin moisturising compositions as claimed in claim 1 wherein the excipients are emulsifiers and structurants.

Skin moisturizing compositions as claimed in any of the preceding claims wherein the emulsifiers are 0.5 to 5.0% and structurants are 0.1 to 10.0% of the composition. Skin moisturising compositions as claimed in any of the preceding claims wherein the emulsifiers are selected from polyetheylene glycol stearyl ethers, addition products of ethylene oxide and/or propylene oxide, and linear fatty alcohols having 8 to 22 carbon atoms or fatty acids having 12 to 22 carbon atoms, glycerol mono- and diesters of saturated fatty acids having 6 to 22 carbon atoms and ethylene oxide addition products.

Skin moisturising compositions as claimed in any of the preceding claims wherein the structurants are selected from fatty alcohols and thickeners.

Skin moisturising compositions as claimed in any of the preceding claims wherein the thickening agent is selected from carbomer, acrylic acid polymers such as homopolymers, copolymers and cross-polymers, cross linked polyacrylic acid salts, cross linked acrylic copolymers, carboxymethyl cellulose, carboxy vinyl polymers, Hydroxy ethyl cellulose, Hydroxy propyl cellulose, methyl cellulose, Xanthan gum, Carrageenan, Alginic acid salts, Pectin , Gum Arabic, Gatch gum, araya gum, Tragacanth gum, Agar powder, Bentonite.

Skin moisturising compositions as claimed in claim 7 wherein the Carbomer, Cross linked acrylic coplymers and Xanthan gum are preferred.

Skin moisturising compositions as claimed in any of the preceeding claims wherein the sensory modifiers are selected from esters (such as Isopropyl Myristate, Isopropyl Palmitate, Heptyl undecylenate, Neopentyl glycol Dihetanoate, ester ethers such as fatty acid esters of ethoxylated fatty alcohols, Silicones such as Cyclomethicone, Dimethicone .

Skin moisturising compositions as claimed in any of the preceding claims wherein sensory modifiers are included in the compositions containing coconut oil from 10- 30% .

A process for the preparation of moisturising compositions comprising steps: i) Preparing a water phase by mixing water and preservatives followed by addition of thickener with heating upto 70°C,

iv) Adding neutralizer followed by the optional addition of a sensory modifier with heating upto 50 °C.