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GENETIC ENGINEERING The method of changing inherited characteristics of an organism by altering its genetic material is called genetic engineering. It is also known as Recombinant DNA technology. Recombinant DNA technology is the technique, which allows DNA to be produced via artificial means. The procedure has been used to change DNA in living organisms and may have even more practical uses in the future. It is an area of medicine, which is at present in its initial phase of the overall concerted effort. The cornerstone of most molecular biology technologies is the gene. To facilitate the study of genes, they can be isolated and amplified. One method of isolation and amplification of a gene of interest is to clone the gene by inserting it into another DNA molecule that serves as a vehicle or vector that can be replicated in living cells. When these two DNAs of different origin are combined, the result is a recombinant DNA molecule. 1. TOOLS OF GENETIC ENGINEERING The tools of

SPECIALIZED PHARMACEUTICAL EMULSIONS 1.INTRODUCTION: 1.1 DEFINITION “A biphasic system consisting of two immiscible liquids, one of which (the dispersed phase) is finely and uniformly dispersed as globules throughout the second phase (the continuous phase).” Since emulsions are a thermodynamically unstable system, a third agent, the emulsifier is added to stabilize the system (Agarwal and Rajesh, 2007). Emulsifier stabilizes the system by forming a thin film around the globules of dispersed phase (Javed et al., 2008). Either the dispersed phase or the continuous phase may vary in consistency from that of a mobile liquid to semisolid (Alfred, 2005). Thus, pharmaceutical emulsions range from lotions (low viscosity) to creams (high viscosity). The particle size of the dispersed phase commonly ranges from 0.1 to 100 μm (Agarwal and Rajesh, 2007). 1.2 COMPOSITION An emulsion usually consists of following three components:  Aqueous phase.  Oily phase.  Em