FEBRUARY 2015 • Vol. 21 No. 2
New York Society of Cosmetic Chemists
www.nyscc.org
Applications of Maleic Anhydride Chemistry in Skin Care, Biomedical Devices, and Transdermal Delivery. Part II … by Roger L. McMullen
I
n the first article of this series, we discussed several applications of maleic anhydride chemistry to phenomenon occurring in skin. Copolymers of maleic anhydride are used universally in the biomedical industry as bioadhesives, allowing for the attachment of biomedical devices to the skin. Not surprising, the same types of polymers found their way into personal care adhesive strips designed to remove unwanted keratotic debris. In a much different application, maleic anhydride derivatives maneuvered into antiperspirant formulations where they help to reduce the concentration of aluminum salts. Transdermal drug delivery is another explosive area where hydrogels made of maleic anhydride polymers act as key ingredients of the delivery formulation. As you will see in the paragraphs that follow there have been many advances made in optimizing transdermal delivery components over the last decade. Much of this understanding comes from studies aimed at exploiting the hydrogel properties of maleic anhydride polymers used in conjunction with plasticizing agents. Moreover, maleic anhydride derivatives have been at the forefront of key advances in transdermal delivery including microneedles and nanoparticle technology.
Transdermal Patch Applications Maleic anhydride copolymers have been incorporated into the most basic transdermal delivery vehicle known as the patch. The essential components of the bioadhesive patch consist of a bioadhesive polymer in combination with a backing material (e.g., nylon), plasticizer, and pharmaceutical active ingredient to be delivered to skin. The plasticizer is a key component of this formulation. In the case of poly(methyl vinyl ether-maleic anhydride) the Tg of the dry powder is 151 °C, while in the free acid form (i.e. when the polymer is dissolved in H2O) the Tg drops to 141 °C due to increased flexibility of the free acid structure.1 Regardless, films cast from poly(methyl vinyl ether-maleic acid) solution are brittle and not suitable for transdermal delivery applications by themselves. Thus, a plasticizer must be employed in combination with poly(methyl vinyl ether-maleic acid) in order to form a hydrogel system.
Choosing a Proper Plasticizer to Form a Patch Hydrogel Researchers at Queens University Belfast conducted a great deal of research over the last decade trying to find a suitable plasticizer (Continued on page 4)
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T h e J e w i s h M u s e u m • N e w Yo r k , N Y Regi str at ion closes Febr uary 27, 2015 (more informat ion on page 13 )