**Abstract**

Microemulsions are lipid based drug delivery system consisting of oil, water, surfactant and often a co-surfactant. They are prepared in order to deliver the drug in an effective manner so as to obtain the desired therapeutic activity. Compared to other conventional therapy, they can deliver the drug in an efficient manner because of their characteristics like reduced particles size, lipid based drug delivery system, thermodynamic stability and economical scale up. Anti-cancer drugs can be easily incorporated into microemulsion so as to target the cancer cells. This helps in increasing the solubility, permeability and absorption of the poorly soluble and poorly permeable drugs, thereby helping in enhancing the bioavailability of the drug. In this chapter, we are also focusing on the herbal based formulations that will be helpful in effectively fighting against cancer cells with less or no side effects. A light has also been shed on the advantages and disadvantages of the microemulsions that will be helpful in considering them as an effective model to conquer cancer and promote the same in the upcoming years.

**Keywords:** cancer, microemulsion, anti-proliferative activity, herbal compound, lipid based delivery

#### **1. Introduction**

Microemulsions are lipid based drug delivery system consisting of oil, water, surfactant and often a co-surfactant. They are prepared in order to deliver the drug in an effective manner so as to obtain the desired therapeutic activity [1]. Compared to other conventional therapy, they can deliver the drug in an efficient manner because of their characteristics like reduced particles size, lipid based drug delivery system, thermodynamic stability and economical scale up [2]. Anti-cancer drugs can be easily incorporated into microemulsion so as to target the cancer cells [3]. In this chapter, we are also focusing on the herbal based formulations; this will be helpful in effectively fighting against cancer cells with less or no side effects. The advantages and limitation of the microemulsions discussed in this chapter will also be helpful in considering them as an effective model to conquer cancer and promote the same in the upcoming years.

As said earlier, the microemulsions are lipid based drug delivery systems that are involved in effectively delivering the drug to the target site [4, 5]. The term microemulsions were employed by T.P. Hoar and J.H. Shulman in 1943 [6]. The word microemulsion was also called as transparent emulsion, solubilized oil

*Perspective Chapter: Microemulsion as a Game Changer to Conquer Cancer with an Emphasis… DOI: http://dx.doi.org/10.5772/intechopen.101479*

and micellar solution etc. The microemulsions are optically isotropic in nature and they are also thermodynamically stable. It has been stated that according to IUPAC the diameter of the particle can approximately vary from 1 to 100 nm that can be usually between 10 and 50 nm [7]. Basically the microemulsions can be divided into oil in water (O/W) type, water in oil (W/O) type and bicontinuous microemulsion with high solubilizing power [8, 9]. The different types of microemulsion are given in **Table 1**.

While coming to the theories of microemulsion, there are basically three theories as follows:


### **2. Composition and method of preparation of microemulsion**

#### **2.1 Composition of microemulsions**

Basically, the mircoemulsion consists of three main ingredients including water, oil and surfactant.

#### *2.1.1 Water phase*

Aqueous phase plays an important role in the formulation of microemulsion. Based on the type of microemulsion, they act as either a dispersion medium or a dispersed phase in the microemulsion [13]. This phase can accommodate the hydrophilic active drug and some of the preservatives. Sometimes they are also replaced by the buffer solution. In case of water in oil microemulsion, the addition of the water makes changes in the concentration of the surfactant/ water ratio. Dilution of the microemulsion further with the water leads to the phase separation thus, disrupting the droplet formation. Hence, in order to obtain a stable microemulsion, the accurate water ratio must be employed [6].

#### *2.1.2 Oil phase*

They are the most important component in the microemulsion system to solubilize and transport the lipophilic compounds via the lymphatic system. It also increases the GI (gastrointestinal) absorption of the drug. The selection of oil is determined based on the solubility of the drug in that particular oil. Example of oil includes olive oil, castor oil, capryol 90, oleic acid and isopropyl myristate etc. [6, 8, 14].
