MENTHOL AS A PARABENS ALTERNATIVE

Abstract

A method and composition for substituting menthol or a menthol related compound for parabens as a preservative agent in cosmetic and pharmaceutical compositions. The invention provides a means to make cosmetic and pharmaceutical products saber and more marketable by removing all parabens and relying on the antibiotic properties of menthol, or menthol derivatives, to provide antibiotic preservative functions.

Claims

1. A preservative agent for preventing microbial growth in a topical cosmetic preparation, the preservative agent comprising menthol, wherein the topical cosmetic preparation does not contain parabens.

2. The preservative agent of claim 1, wherein the menthol concentration is between 0.1% and 10% in the preparation.

3. The preservative agent of claim 2, wherein the menthol concentration is 0.25%.

4. (canceled)

5. (canceled)

6. (canceled)

7. A composition for use in a topical cosmetic preparation that does not contain parabens, the composition comprising menthol as a preservative agent for preventing microbial growth in the topical cosmetic preparation.

8. The composition of claim 7, wherein the menthol concentration is between 0.1% and 10% in the preparation.

9. The composition of claim 8, wherein the menthol concentration is 0.25%.

10. (canceled)

11. (canceled)

12. (canceled)

Description

DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention relates to menthol, and menthol-related compounds. As used herein, the terms “menthol” and “menthol-related compounds” are synonymous and shall mean both synthetic menthol and naturally-occurring menthol-containing compounds such as the peppermint oil, corn mint oil, eucalyptus oil, citronella oil, Indian turpentine oil, camphor oil, and cinnamon oil. The invention may further comprise alternate preparations including a base or vehicle. Menthol can be compounded in a non-biologically active base, or in a biologically active base.

[0017] Menthol is an organic compound made synthetically or obtained from corn mint, peppermint or other mint oils. It is a waxy, crystalline substance, clear or white in color, which is solid at room temperature and melts slightly above room temperature. Menthol has known local and counterirritant qualities, and it is widely used to relieve minor throat irritation. Menthol also acts as a weak kappa opioid receptor agonist. A topical menthol preparation can be used on the skin as an analgesic, an astringent irritant, or a cooling compound, depending on the menthol concentration. For example a 10% menthol preparation provides analgesic action (e.g. Icy Hot, Mentholatum), a 5% menthol preparation provides astringent action (e.g. Listerine), and all topical menthol preparations having a concentration of greater than 0.01% can be bacteriostatic (stop bacteria from growing) or bactericidal (kill bacteria), but with varying effectiveness.

[0018] Regulations for preservative agents that prevent the growth of bacteria are mandated by regulatory agencies worldwide for cosmetic and pharmaceutical products, and are documented by Antimicrobial and Preservative Effectiveness Testing (AET and PET), with strict protocols. The present invention is based on the discovery that menthol, or menthol related compounds, can be an effective antimicrobial and preservative agent in cosmetic and pharmaceutical compositions. This can be accomplished by removal of all parabens in cosmetic and pharmaceutical compositions that contain menthol in an effective concentration to pass Antimicrobial and Preservative Effectiveness Testing protocols. Preservative and antimicrobial effectiveness can also be accomplished by substituting menthol or a menthol related compound for the parabens in cosmetic or pharmaceutical compositions that do not already contain menthol.

[0019] The present invention can be used in a preservative effective in preventing microbial growth on or in a cosmetic or pharmaceutical preparation. In a preferred embodiment, the preservative is menthol in amounts effective to inhibit microbial growth on or in the preparation, wherein the preparation does not contain parabens. The invention can also be used in a composition for use in a cosmetic or pharmaceutical preparation that does not contain parabens, the composition comprising menthol as an antimicrobial preservative agent. The menthol concentration is typically between 0.1% and 10% in the inventive cosmetic or pharmaceutical preparation. In a preferred embodiment the menthol concentration is 0.25%. The menthol concentrations disclosed herein are intended to be sufficient to pass antimicrobial and preservative effectiveness testing for the cosmetic or pharmaceutical preparation, to comply with regulatory bans on parabens used in cosmetic and pharmaceutical preparations, and with cosmetic and pharmaceutical retailer's bans on paraben containing products.

[0020] U.S. Pat. Nos. 6,322,493 and 6,702,733 to Ronald J. Thompson (co-inventor of the present invention), which are incorporated herein by reference in their entirety, disclose the use of a topical, clitorally-applied cream composition of menthol+1-arginine, which has been marketed under the trade names Sensua and Alura. This composition was FDA approved as a topical medicament in 2002. While the inclusion of menthol in this composition was initially intended as a vehicle to allow the absorption of the L-arginine into tissues and to reflexively increase vaginal lubrication through reflex nocieoceptors, recently the inventors have investigated whether the menthol component of this composition has bactericidal and fungicidal properties that make menthol useful as a parabens alternative preservative, with the ultimate intention of allowing the product to be marketed as “parabens free”.

[0021] Data: A 90-day Accelerated Stability Report was done for a composition comprising menthol+1-arginine packaged as a clear to slightly cloudy gel containing no methylparaben, in 1.2 ml packets. The purpose of this hold study was to determine if a composition containing menthol+1-arginine but containing no methylparaben could pass all required testing when held in 1.2 ml foil packets at 40° C. and 75% relative humidity over a 90 day period. 1,500 of the foil packets were placed on accelerated stability (40° C.±2° C. at 75% relative humidity+5%) in a random orientation, for a period of 3 months. 220 packets were pulled at 30, 60 and 90 days for analytical testing. An additional 110 packets were pulled at the 90 day time point and sent out for microbial testing. The remaining packets were kept in the event additional samples were required until all testing was completed, at which point they were destroyed.

[0022] Sampling and testing was performed at time zero (0-Days), 30-days, 60-days, and 90-days from the date the stability was initiated (Dec. 12, 2014) for one R&D batch of the product (Batch C41036-RD). The stability of the product in the 1.2 ml foil packets was evaluated in this study. The packets were filled with the bulk product (menthol+1-arginine, with no methylparaben) and were stored to simulate an advanced stability. At the specified time intervals, 220 of the packets were pulled from the stability chamber and emptied into an 8-oz cup in order to create a large enough sample for the required testing, to be evaluated. The testing parameters were for appearance, color, odor, pH, and viscosity to determine viability. Additionally, microbial testing was also performed at time zero (0-Days) and 90-days. Results: This hold study showed that a composition containing menthol+1-arginine, with no methylparaben can be stored in 1.2 ml foil packets for up to 90 days under the conditions of 40° C. and 75% relative humidity without any degradation to the final product that would cause the product to fall out of established specifications. Further, microbial examination of the non-sterile product for specified organisms showed that there was no growth of Staphylococcus aureus, Pseudomonas aeruginosa, or Candida albicans over the 90 day period. These data show that menthol has bactericidal and fungicidal properties that make menthol useful as a parabens alternative preservative.

[0023] While the present invention has been illustrated by the description of embodiments thereof, and while the embodiments have been described in considerable detail, it is not intended to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will be readily apparent to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative system and method, and illustrated examples shown and described. Accordingly, departures may be made from such details without departing from the scope of the invention.