Pearlitol SD 200 based proliposomes
Ketoprofen proliposome formulations using pearlitol SD 200 and different ratios of HSPC and cholesterol were prepared. HSPC (a high phase transition temperature lipid) and cholesterol (for structural rigidity) were selected because of their lower risk of oxidation and improved stability of liposomes respectively. However any variation in the composition of HSPC and cholesterol results in the deformation of vesicle, which leads to drug leakage and fusion of vesicle with gastrointestinal epithelium (32). To conquer the lipid to cholesterol composition in developing stable proliposomes varying ratios of HSPC to cholesterol (total lipid mixture of 250 µM) were investigated.
Physicochemical characterization of proliposomes
Formation of liposomes from proliposomal powders
Stepwise formation of liposomes from proliposomes upon hydration was observed under optical microscope and represented in Figure 2 A-D. Proliposomal powder (Figure 2A) upon contact with distilled water resulted in the formation of tubular structures (Figure 2B) due to instantaneous surface lipid hydration of proliposomes followed by budding off and liposome formation until the surface lipid hydration and solubility of the water soluble carrier ends. The hydrophilic nature of pearlitol might also facilitate the quick hydration of proliposomes to transform into liposomes. Under stagnant conditions (without agitation) liposomes formed are aggregates as shown in Figure 2C. Optical microscopic images of the liposomes formed upon hydration with manual agitation (Figure 2D) confirms separation of liposomes from aggregates and dispersion of spherical shape liposomes in the medium.
Micromeritics
Oral administration of proliposomal powders whi...
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...om aggregation and floating behavior of drug particles during dissolution. All proliposomal powders showed 67.5 to 91.2% drug release with following order KPL3>KPL5>KPL0>KPL4>Pure drug within 5 min which indicated improved dissolution of drug in the form of proliposomes. The improved dissolution of ketoprofen in proliposomal formulation may be due to the hydrophilic nature of pearlitol which facilitate the quick hydration of proliposomes to transform into liposomes, enhanced solubility of poorly water soluble drug by amphiphilic HSPC or altered physical state of drug entrapped in the bilayers from crystalline to amorphous state and it may be also due to increased effective surface area and wetting characteristic of unentrapped drug upon contact with dissolution medium as fine dispersion which was adsorbed over the porous water soluble carrier i.e. pearlitol SD 200.
explain the formation of micelles and bi-layers from lipid amphiphilicity. A variety of books were
Vemuri S. & Rhodes CT., 1994. Preparation and characterization of liposomes as therapeutic delivery systems: a review. Pharmaceutics Acta Hebetiae, 70, 95-111.
The endothermic melting temperature for Ptx, blank S-SEDDS, physical mixture of Ptx/blank S-SEDDS, and Ptx-loaded S-SEDDS was determined by DSC 2920. Samples were scanned from 30 to 250 °C at a rate of 10 °C /min. In all the cases, an empty pan was used as the reference. XRD patterns of Ptx, blank S-SEDDS, physical mixture of Ptx/blank S-SEDDS and Ptx-loaded S-SEDDS were recorded using an X'Pert PRO Multipurpose X-Ray diffractometer equipped with CuKα radiation (40 kV, 20 mA). The 2θ scanning range was varied from 2° to 50°.
Liposomes are artificial prepared vesicles which are composed of the lipid bilayer. They can be used as a vehicle for nutrients and pharmaceutical drug administration. Liposomes are prepared by disrupting the biological membranes by sonication. Liposomes are closed vehicles that contain both lipophilic and a hydrophilic region. The formation of these vesicles is made by hydrating a mixture of cholesterol and a phospholipid. There are many different approaches to delivering these drugs. Improvements for the performance of the drug molecules are by delayed clearance from the circulation and protecting the drug from the environment and limiting the effects to the target cells. “Liposomes was discovered about 40 years ago by Bangham and his coworker.” (Boddyreddy, 2012) which was an accidently discovery because he was studying blood clotting.
The main lipids components of the cell membrane are the sphingolipids, cholesterol, and other phospholipids. The most predominant element of the sphingolipid molecule in the cell membrane is sphingomyelin, which is composed of a hydrophilic phosphorylcholine headgroup and a highly hydrophobic ceramide molecule. The ceramide group in sphingomyelin composed from amide ester of the sphingoid base D-erythro-sphingosine and a fatty acid of C16–C26 chain length. The lateral association of sphingolipids and cholesterol promoted by a strong interaction between the cholesterol sterol ring structure and the ceramide molecule of sphingomyelin, which are facilitated by hydrogen bonds and hydrophobic van der Waal interactions in addition to hydrophilic interactions and thus the split-up from other phospholipids into distinct microdomains (Brown & London, 1998). These microdomains have been termed rafts that play a function in aggregation of receptor molecules and the reorganization of intracellular signaling molecules to transmit a signal into the cell.
The cell plasma membrane, a bilayer structure composed mainly of phospholipids, is characterized by its fluidity. Membrane fluidity, as well as being affected by lipid and protein composition and temperature (Purdy et al. 2005), is regulated by its cholesterol concentration (Harby 2001, McLaurin 2002). Cholesterol is a special type of lipid, known as a steroid, formed by a polar OH headgroup and a single hydrocarbon tail (Wikipedia 2005, Diwan 2005). Like its fellow membrane lipids, cholesterol arranges itself in the same direction; its polar head is lined up with the polar headgroups of the phospholipid molecules (Spurger 2002). The stiffening and decreasing permeability of the bilayer that results from including cholesterol occurs due to its placement; the short, rigid molecules fit neatly into the gaps between phospholipids left due to the bends in their hydrocarbon tails (Alberts et al. 2004). Increased fluidity of the bilayer is a result of these bends or kinks affecting how closely the phospholipids can pack together (Alberts et al. 2004). Consequently, adding cholesterol molecules into the gaps between them disrupts the close packing of the phospholipids, resulting in the decreased membrane fluidity (Yehuda et al. 2002).
HpUrel is reported to measure 45 A in height and 95 A in diameter. The HpUrel is also reported to have the structure of six protomers put together in a hexametric ring, which surrounds a bilayer of lipids. This native hexametric structure for HpUrel was confirmed with the use of blue native gel electrophoresis. In the periplasmic leaflet there are six lipid tails. In the cytoplasmic leaflet, there are eighteen lipid tails. Each protomer surrounds a channel, which is formed by six trans-membrane helices. This bundle of helices has a fold, which is seen as a two-helix hairpin pattern that is repeated three times around the center axis of the channel. With these findings, effective treatments for Helicobacter Pylori, and possibly even a cure to this infection can now have a greater chance of being found.
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
The term nanocarriers includes a wide range of different nanosized drug delivery systems. The oldest and at the same time the most clinically established nanocarriers are liposomes, spheres composed of an aqueous core surrounded by one or more concentric lipid bilayers. They are suited for the encapsulation of both hydrophillic and hydrophobic drugs, respectively in the aqueous core and whitin the lipid membrane (Hafner e.a. 2014). Liposomes increase thus the solubility of hydrophobic compounds, they enable trapping of drug molecules with a high potency, they reduce systemic side effects and toxicity and they attenuate drug clearance (Riehemann e.a. 2009)
showed that phosphorlyation is not neccessary for Smo translocation but rather inhibition of Smo endocytosis was sufficient to drive Smo to the plasma membrane. This was observed by fluorescently labelling Smo with GFP and tracking its location following either treatment with Hh or Dynasore, a pharmacological inhibitor of dynamin-mediated endocytosis (Macia et al., 2006). In both cases Smo translocated to the plasma membrane. The same was done for a nonphosphorylatable SmoSA-GFP fusion in which the inhibition of endocytosis by treatment with Dynasore caused SmoSA to translocation to the plasma membrane. The observation that SmoSA can also be present at the membrane demonstrates that some exchange between the intracellular and plasma membrane bound pools must also occur for nonphosphorylated
These are also very helpful for the drug encapsulation which are discharge on disintegration of polymer layer network. The factors on which the physically cross linked microgels are depends are polymer composition, ionic strength of the medium and on temperature. The physically cross linked microgels are prepared from the biopolymers such as dextron, agarose and alginate[24]. This is also very important type of microgels used in many fields.
Brigger I, Duberne C, Couvreur P, (2002). Nanoparticles in cancer therapy and diagnosis. Advanced Drug Delivery Reviews, 54, 631-651.
Analysis of Aspirin Tablets Aim --- To discover the percentage of acetylsalicylic acid in a sample of aspirin tablets. ----------------------------------------------------------------- In order to do this, the amount of moles that react with the sodium hydroxide must be known. This is achieved by using the method of back titration.
Several factors affect the action of disintegrants such as: ratio of the disintegrant in tablet, particle size, molecular structure, compression force, method of incoroporation, compatibility with other excipients, adding more than one disintegrant, addition of surfactant, tablet hardness the tablets, API nature , mixing, screening and others [5,10,11]. In 1980, Rundic and co-workers found that larger CPV grades (with larger particle size) are more efficient than smaller one [12]. Later in 1981, Smallenbroek et al studied the effect of particle size of the disintegrant on the disintegration of tablet, they found that larger particle size are more efficient than smaller one [13]. Later, Rundic and co-workers studied the effect of crosslinking
Glycosides might be phenol, liquor or sulfur mixes. They are portrayed by a sugar bit or moiety connected by an exceptional attach to one or non-sugar parcels. Many plants store chemicals as inert glycosides, which can be enacted by catalyst hydrolysis (40). Glycosides have therapeutic properties, for example, anticancer (41), narcotic (42) and stomach related properties (43).