Critical opinion about article - Literature review Example

Introduction While the function of drug coatings in medications are rarely considered by the consumer, they are vital to the function and efficacy of most modern medicines. By incorporating a drug into a polymer film, gel, or other encapsulating material, the hydrophobic molecules can be made to degrade much more slowly [1]. The use of an encapsulating membrane allows the chemical to circulate within the body, while also creating a hydrophilic shell that can pass through the cell membrane of the bacterial target [1, 2].

The coatings also may have the additional property of bioadhesion, keeping the drug at the target site for a longer period of time [3]. Niosomal membranes, non-ionic surfactant vesicles, are one common type of encapsulating material, especially for transdermal and ophthalmic topical use [4, 5]. Niosomes can also be made into a substance called proniosomes, a dehydrated powder formulation of niosomes, which can be transported further and stored longer, increasing their usefulness [6]. Niosomal Encapsulation and Hydrogen Bonding In their 2011 study, Hao and Li examined the efficacy of niosomal entrapment in solution, specifically on the rate of encapsulation when the niosomes were included in a solution that also contained the desired chemical for entrapment [7].

Niosomal encapsulation is achieved by coating a water-soluble pharmaceutical chemical with a lipid membrane, and this lipid coating will slow the release of the encased pharmaceutical chemical into the surrounding environment. This is usually made use of in such situations as a time-released or delayed-release medication [5]. Additionally, the use of a niosomal membrane around the pharmaceutical chemical is currently the only known method for achieving safe and efficient transdermal drug delivery.

The ability of the niosomal membrane to help the pharmaceutical chemical cross the dermal and subdermal layers is dependent on the structural organization of niosomes, not simply on the properties of the niosomal membrane. Other non-ionic surfactants do not produce the same successful results for transdermal permeation [4]. One of the chemical models in the Hao and Li study, p-hydroxyl benzoic acid, was found to form hydrogen bonds with the niosomal membrane being studied [7]. These hydrogen bonds caused an increase in the entrapment efficiency of the formulation.

This can be seen in the fact that the second model used in their study, salicylic acid, showed lower rates of entrapment efficiency. Salicylic acid also did not form the same type of hydrogen bonds with the niosomal membrane, showing that the increased encapsulation efficiency seen in the p-hydroxyl benzoic acid solution was therefore related to the hydrogen bonding of the solute to the niosomal membrane. Figure 1 shows the changes in the UV absorption spectra of the solutions being studied which indicate the presence of hydrogen bonding between the niosomal coating and the p-hydroxyl benzoic acid.

Conversely, these spectra also show the lack of such hydrogen bonding in the salicylic acid solution and the blank niosome solution. This study is the first to note the importance of those hydrogen bonds in the functioning of the niosomal membrane and the relation of those bonds to encapsulation efficiency [7]. Niosomes are able to form those hydrogen bonds by providing “a stable system that allows the self-assembly of hydrogen-bonded receptors to occur in contact with aqueous environments”