Introduction
Emulsions are a dispersion system composed of two immiscible liquids or more. One of the liquids is dispersed as small fine droplets throughout the other liquid. Depending on the dispersed and external phases, emulsions can be classified as: water-in-oil emulsions which are fine aqueous droplets dispersed in an oily hydrophobic continuous phase or oil-in-water emulsions which are fine oily droplets dispersed in an aqueous hydrophilic continuous phase. Other types are multiple emulsions which consist of a dispersed phase containing droplets of another phase for example w/o/w or o/w/o. Microemulsions are based on the size of the liquid droplets. These comprise of spherical or cylindrical droplets having a size between 10 – 120 nm (Mehta, S & Kaur, G 2011) dispersed in another phasing using an emulsifier or a mixture of emulsifier in high concentration (15 -25%). Emulsions are thermodynamically unstable due to the large surface area between the two phases resulting in a high interfacial energy. The system will try to lower the energy by reducing the area of contact between the two phases resulting in coalescence of the dispersed phase, droplet size enlargement and eventually phase separation. Therefore it’s important to stabilise the interface between the two immiscible phases. This is done by the addition of an appropriate emulsifying agent. These are amphiphilic surfactants containing both hydrophilic and hydrophobic characters. Therefore they are classified according to the balance of characteristics using the hydrophilic-lipophilic balance (HLB) system. The HLB values range from 0 to 20 on an arbitrary scale with each surfactant having a unique value. The higher region of the scale includes hydrophilic surfactants su...
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...sicochemical Principles of pharmacy, 4th edition, A. T. Florence and D.Attwood (Ed.), Pharmaceutical Press (2006), Chapter 4: Drug stability, pages 93-138.
Martin’s Physical Pharmacy and Pharmaceutical Sciences, 5th edition, A. P. J. Sinko, Lippincott Williams and Wilkings (2006), Chapter 15: Chemical kinetics and stability, pages 397-434.
Francoise Nielloud, F. (2000). Pharmaceutical emulsions and suspensions. [Online access] Google Books. Available at: http: http://books.google.co.uk/books?id=hDOS5OfL_pQC&printsec=frontcover&dq=emulsions&hl=en&sa=X&ei=AnVeU- r0NsnF7Ab8qYG4CQ&ved=0CFUQ6wEwBg#v=onepage&q=emulsions&f=false
Dipak Kumar, Sarker. (2013). Pharmaceutical Emulsions: a drug developer’s toolbag. [Online access] Google Books. Available at: http://books.google.co.uk/books?id=XHgoAgAAQBAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false
At this point the identity of the unknown compound was hypothesized to be calcium nitrate. In order to test this hypothesis, both the unknown compound and known compound were reacted with five different compounds and the results of those reactions were compared. It was important to compare the known and unknown compounds quantitatively as well to ensure that they were indeed the same compound. This was accomplished by reacting them both with a third compound which would produce an insoluble salt that could be filte...
Firstly, an amount of 40.90 g of NaCl was weighed using electronic balance (Adventurer™, Ohaus) and later was placed in a 500 ml beaker. Then, 6.05 g of Tris base, followed by 10.00 g of CTAB and 3.70 g of EDTA were added into the beaker. After that, 400 ml of sterilized distilled water, sdH2O was poured into the beaker to dissolve the substances. Then, the solution was stirred using the magnetic stirrer until the solution become crystal clear for about 3 hours on a hotplate stirrer (Lab Tech® LMS-1003). After the solution become clear, it was cool down to room temperature. Later, the solution was poured into 500 ml sterilized bottle. The bottle then was fully wrapped with aluminium foil to avoid from light. Next, 1 mL of 2-mercaptoethanol-β-mercapto was added into fully covered bottle. Lastly, the volume of the solution in the bottle was added with sdH2O until it reaches 500 ml. The bottle was labelled accordingly and was stored on chemical working bench.
explain the formation of micelles and bi-layers from lipid amphiphilicity. A variety of books were
Pinto Reis C., Neufeld RJ., Ribeiro AJ., & Veiga F., 2006. Nanoencapsulation I. Method for preparation of drug-loaded polymeric nanoparticles. Nanomedicine: Nanotechnology, Biology and Medicine, 2, 9-21
However, low HLB surfactants may also be an important component of oral lipid-based formulation by behaving as a coupling agent for the high HLB surfactants and the lipophilic solvent components, as well as contributing to solubilization by remaining associated with the lipophilic solvent post-dispersion. Moreover, using a blend of high and low HLB surfactants may also lead to more rapid dispersion and finer emulsion droplet size upon addition to an aqueous phase [36, 48, 49, 51–55]. Thus, in this study, we decided to mix Tween 80 (high HLB value) with Carbitol (low HLB value) to identify the most effective combination emulsifying with three chosen oils. The size of the emulsion droplets decreased as the HLB value of surfactant mixture reached the required HLB (Table 2). In the case of soybean oil, the smallest size was 277 ± 2.49 nm obtained at 20:80 (v/v) ratio of Tween 80:Carbitol). In the cases of ethyl oleate (Tween 80:Carbitol, 90:10, v/v) and IPM (Tween 80:Carbitol, 60:40), the smallest droplet sizes were 2.9 ± 0.170 and 10.5 ± 0.596 nm, respectively. These results show that the combination of Tween 80 and Carbitol had extremely good emulsifying ability, resulting in a fine emulsion in the cases of using ethyl oleate and IPM oil. The results of the visual test (Fig. 1) are parallel to the results of droplet size measurements. The combinations that had a smaller droplet size of 100
Rogers, D. H.; Morris, J. C.; Roden, F. S.; Frey, B.; King, G. R.; Russkamp, F. W.; Bell, R. A.; Mander, L. N. Pure Appl. Chem., 1996, 68, 515.
Discuss the possible drug and excipient-related constrains of the formulation (no identity of the drug was given to you at this
In part A of the lab, our group measured the effects of emulsification on the digestion of lipids in the presence of cholic acid, a purified bile salt, and distilled water. The tube containing vegetable oil and no bile began to separate into two layers within the first minute of being mixed together. Although there were no clear distinctions within the first 15 seconds, by the fifth minute, there appeared two separate layers; one resulted in a yellow appearance while the other one was clear. As expected and predicted in our hypothesis, it was easier to notice the separation of the two layers in the tube without any bile salts because lipids are hydrophobic meaning that oils are more difficult to digest. However, due to the fact that when in the presence of bile salts, lipids
...degree of intermolecular association. By adjusting the formulation or the chemical moieties of the drug delivery system, the moment and the location of the release of the drug may be controlled (You e.a. 2010).
In the most basic sense, as described in Fennema’s Food Chemistry, an emulsion is a “dispersion of one liquid into another.” The properties of these mixtures are defined by the type of emulsion (oil in water or water in oil), droplet size, volume fraction of the dispersed phase, composition of the surface layer and composition of the continuous phase. Droplet size is important to emulsions in that a finer droplet size, typically 1 um, generally yields a more stable emulsion (Srinivasan and others, 2008). The volume fraction is imp...
Many things change and alter how a hydrocolloid substance reacts. Factors added to hydrocolloid mixtures, such as water depending on the amount, can yield a gel or liquid substance. When heat is added or eliminated, the hydrocolloid mixture’s physical behavior changes. They may thicken at low doses to make a gel substance, some may be used as emulsifiers and others may also be used as whipping agents to create foams. When a hydrocolloid is dissolved in water, the water gathers around and is attracted to the sugar units, forming a layer of water with restricted movement. It is this ability to organize and control water that gives hydrocolloids their ability to thicken and gel. With the exception of gelatin, which is a protein, hydrocolloids are polysaccharides (fats) and or complex sugars (carbohydrates). Which is another interesting thing, Hydrocolloids come in all three forms of nutrients. The properties of any hydrocolloid are based on its physical structure (sugars made from) and its chemical properties: size, charge, and the
Gusdinar T. COMPLEXOMETRIC TITRATION An application method of Inorganic Pharmaceutical Analysis [homepage on the internet] . No date. [cited 2014 Mar 20]. Available from: http://download.fa.itb.ac.id/filenya/Handout%20Kuliah/Inorganic%20Pharmaceutical%20Analysis%202008/English%20Version/05.%20COMPLEXOMETRIC%20TITRATION.pdf.
Thickett, Geoffrey. Chemistry 2: HSC course. N/A ed. Vol. 1. Milton: John Wiley & Sons Australia, 2006. 94-108. 1 vols. Print.
V. Amarnath, D. C. Anthony, K. Amarnath, W. M. Valentine, L. A. Wetterau, D. G. J. Org. Chem. 1991, 56, p. 6924-6931.