Emulsions formulation development

In many cases, the solubility of a water-insoluble drug can be enhanced by adding a cosurfactant to a surfactant solution. Such solubility enhancement is useful for mixed micelle and emulsion formulation development. 

There are a number of physical-chemical properties of emulsions that are important to consider when developing an emulsion formulation for a drug. These include, but are not limited to, particle (droplet) size, viscosity, osmolarity, and zeta potential, which are used to monitor the physical stability of emulsions. Assays of potency and degradant levels are used to monitor the chemical stability of emulsions. 

Conformance to one or more of the above criteria generally qualiLes development of an emulsion formulation for drugs that otherwise cannot be successfully administered parenterally as a solution. Hence, emulsions have been explored for improved drug efLcacy after oral, topical and parenteral administration, and for improved patient compliance (e.g., reduced pain or irritation after parenteral administration, and improved palatability after oral delivery). 

Constantinides, P. P, K. Lambert, A. Tustian, S. Lalji, B. Schneider, W. Ma, B. Wentzel, D. Kessler, D. V forah, and S. Q. Quay. 2000. Formulation development and antitumor activity of a lter-sterilizable emulsion of paclitaxel.Pharm. Res. 17 175-182. 

The development of polymer latices and their pigmentation and application is still at an early stage. However, an emulsion formulation suitable as a base for paints has been given. (46) Here a difunctional aminimide(below) is included at 51 in the (CH N lT0C(CH2)gC0]r N (CH ) ... 

Obtaining stable, biocompatible, small-sized, narrowly distributed emulsions of an excretable PFC was crucial. The extreme hydrophobicity of PFCs can, however, render the obtaining of a stable emulsion difficult. Further critical aspects of PFC emulsion development involve emulsion formulation, physical and biological characteristics, scale-up, sterilization, and packaging, as well as its user-friendliness and strategy of use. 

A stable emulsion is considered to be one in which the dispersed droplets retain their initial character and remain uniformly distributed throughout the continuous phase for the desired shelf life. There should be no phase changes or microbial contamination on storage, and the emulsion should maintain elegance with respect to odor, color, and consistency. Instabilities of both chemical and physical origins can occur in emulsion formulations. Chemical instabilities, such as the development of rancidity in natural oils due to oxidation by atmospheric oxygen, the depolymerization of macromolecular emulsifiers by hydrolysis, or... 

By this test we evaluated our standard oil for metal demolding, Rhodorsil H1658, the new development Rhodorsil HI680 PEX, and three modified silicone oils of competitors, each in the standard emulsion formulation. 

Should dissolution rate-enhancing principles be applied in the formulation development (e.g., wetting agents, micronisation, solubilising agents, solid solutions, emulsions and nanoparticles) ... 

Anticancer agents are typically hydrophobic and unstable in water, making formulation development a major undertaking. For this reason, emulsion, the semihomogeneous mixture of two immiscible liquids, is an attractive dosage... 

Synthetic rubber, a dimethylbutadiene, was developed as a substitute for natural rubber in Germany during World War I and saw limited use as an adhesive. In the early 1930s, neoprene rubber (then called Duprene) became available to adhesive manufacturers in the United States, and shortly thereafter in Great Britain. Today, neoprene rubber adhesives are available as both thermoplastic and cross-linking systems in both solvent and emulsion formulations. Neoprene rubber is the major base resin for contact adhesives. A limited amount of neoprene rubber is also used in sealants. 

Thakkar PJ, Madan P, and Lin S. (2014). Transdermal delivery of diclofenac using water-in-oil micro-emulsion Formulation and mechanistic approach ofdrug skin permeation. Pharmaceutical Development and Technology, 19, 373-384. 

For example, advanced sunscreens are supplied as freely dispersed suspension in water, and hydrophilic silica microcapsules enhance the bioavailability of the entrapped active ingredients. Moreover, silica microcapsules from 0/W emulsions are clear and smooth to the touch, ideally suited for cosmetic formulations. Developed by Sol-Gel Technologies, the UV-Pearls know-how and production line were sold by Sol-Gel Technologies to Merck, which started to market them in 2002. These suspensions ( Eusolex UV-Pearls ) are nowadays used by several cosmetic companies to formulate high sun protection factors lotions (Figure 18.4) with improved safety profile. 

The emulsions so far described have been mainly of the simple 0/W type. However, because of their utility in other fields (e.g., cosmetology), an interest is developing in food applications of multiple emulsions, i.e., water-in-oil-in-water emulsions, since fliey modify the behavior of the fat and also offer the potential to carry, in their interior water droplets, materials of nutritional interest (172, 173). However, flic formulation and con trol of such preparations is much more difficult than for simple emulsions (174). The basic principles of such emulsion formulation are well known the water droplets within the oil droplet need to be stabilized using a mixture of lipophilic emulsifiers, whereas the stabilization of the oil droplets requires rather a hydrophilic surfactant. Evidently, the preparation of such emulsions cannot be preformed in a single stage, but requires the preparation of a W/O emulsion first, and then dispersion of this emulsion into an aqueous medium. 

Although most of the development work that led to the current commercial product is still confidential, many basic concepts and unveiled technological breakthroughs have contributed to the current state-of-die-art in emulsion-formulation engineering. 

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