Formulations emulsions

When the propellant is in the internal phase (Fig. 2a), the propellant vapor, upon discharge, must pass through the emulsion formulation in order to escape into the atmosphere. In traveling through this emulsion, the trapped propellant forms a foam matrix. These systems, are typically oil-in-water emulsions. 

The defoamer formulations mentioned so far consist of fairly inexpensive raw materials, but several more cosdy defoaming materials have come into use in paper mills. Hydrophobicized siUca particles are useful in some emulsion formulations. SiUcone solutions and emulsions are very effective in eliminating foam in paper machine water systems. The siUca- or siUcone-based defoamers have higher activity, which somewhat compensates for the higher cost, but care must be taken to prevent ovemse. 

The emulsion formulations are generally appHed to cloth by padding from a bath and squeezing off the excess. Modifying a formulation in the pad box, eg, to increase or decrease firmness, can be easily done by adding an emulsion or softener. The alkaH-soluble vinyl acetate copolymers previously mentioned can be used as warp sizes during weaving. 

F Nielloud, G Marti-Mestres, JP Laget, C Fernandez, H Maillols. Emulsion formulations study of the influence of parameters with experimental designs. Drug Dev Ind Pharm 22(2)359-166, 1996. 

Micro-emulsion formulations of cationic softeners are available and are claimed to have superior fibre penetration properties [484]. Figure 10.59 shows the sorption of a micro-... 

Bouchemal, K., Briangon, S., Perrier, E. and Fessi, H. (2004) Nano-emulsion formulation using spontaneous emulsification solvent, oil and surfactant optimisation. International Journal of Pharmaceutics, 280, 241-251. 

This application was made between 0700 and 0830 a.m. in cool (air temp., 10 0 clear and windless weather. Both granular and emulsion formulations were incorporated to the 7.5cm depth with a disc cultivator within 15 minutes of application. A second cultivation to the same depth, but at right angles to the first, was completed within 2-3 hours. On May 20th both plots were spring-tooth harrowed for seed-bed preparation for soybean planting on the same day. The only subsequent soil disturbance was a row cultivation in late June to control a severe infestation of quack-grass control of broadleaf weeds was essentially complete with the trifluralin. 

The self-emulsifying behaviour of a binary nonlonlc surfactant vegetable oil mixture has been shown to be dependant on both temperature and surfactant concentration. The quality of the resulting emulsions as assessed by particle size analysis showed that manipulation of these parameters can result In emulsion formulations of controlled droplet size and hence surface area. Such considerations are Important when the partition of lipophilic drugs Into aqueous phases and drug release rates are considered. 

A number of other emulsion formulations have been tried as drug delivery systems on an experimental basis. No doubt these studies will continue into the future because emulsions are attractive as drug delivery systems and have been thoroughly studied by a number of researchers. 

Herman, C.J. and Groves, M.J. (1992), Hydrolysis kinetics of phospholipids in thermally stressed intravenous lipid emulsion formulations, J. Pharm. Pharmacol., 44,539-542. 

Whether the system formed on mixing oil, water, and surfactant will be an oil-in-water or a water-in-oil emulsion is a central problem in emulsion technology. It was realized very early that the volume fractions of oil and water are not that important and that the type of emulsion is primarily determined by the nature of the surfactant. Simply speaking surfactants with Ns < 1 tend to form oil-in-water emulsions, while surfactants with Ns > 1 are more likely to form water-in-oil emulsions. Two more detailed guiding principles which are used for practical emulsion formulation are Bancroft s rule of thumb and the more quantitative concept of the HLB scale ... 

Oner, F., Yalin, M, and Hincal, A.A. Stability and hemolytic effect of parenteral lorazepam emulsion formulations,FABAD J. Pharm. Sci, 20, 61-66, 1995. 

Examples of Emulsion Formulations of Water-Insoluble Drugs. 211... 

Challenges with Emulsion Formulations for Drug Solubilization and Delivery. 215... 

Atypical parenteral o/w emulsion is composed of lipid droplets (10-20%), emulsiLer, and osmotic agent it is administered by either intravenous (IV) bolus or IV infusion. In addition, when an emulsion formulation is packed in a multidose container, antimicrobial agents should be included in the formulation to prevent the growth of microorganisms. 

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. 

Use of an emulsion formulation for pharmaceutical drug delivery generally mandates that the drug be present in the internal (i.e., dispersed) phase and at the interface. This means that the process meets one of the following criteria ... 

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). 

Examples of studies supporting use of emulsions for a variety of drug delivery needs are listed in Table 10.4. Some of the advantages conferred by emulsion formulations may be mediated by an improved solubilization of the drug. There is also a growing list of studies suggesting use of emulsions fordrug solubilization perse these are summarized in Table 10.5. 

Penclomedine Prankerd et al. (1988) Emulsion formulation was more active and less toxic in mouse tumor model... 

Halothane Johannesson et al. (1984) Biberetal. (1984) IV administration of emulsion formulation induced anesthesia similar to inhalation route... 

Rhizoxin (NSC 332598) Stella etal. (1988) Solubilization in emulsion formulation for slow infusion... 

Anti-HIV NSC 629243 Strickley and Anderson (1993) Emulsion formulation enhanced solubilization and stabilization... 

Clarithromycin Lovell etal. (1994) Emulsion formulation decreased pain on injection... 

All-trans-retinoicacid (ATRA) Hwang et al. (2004) Emulsion formulation enhanced drug solubilization and stabilization maintained antitumor activity... 

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