All experimental procedures were performed in accordance with the Guidelines for the Care and Use of Laboratory Animals of Shenyang Pharmaceutical University in Shenyang. The smaller the droplet size, the larger the interfacial surface area provided for drug absorption. Phase separation and decrease in drug solubilization are commonly observed at higher temperature than the cloud point due to the susceptibility of surfactant to dehydration [ 42 ]. Self-microemulsifying drug delivery systems are recent and effective approach for the augmentation of oral bioavailability of many poor water soluble drugs provided that the drug should be potent with high lipid solubility. Spernath A, Aserin A.
Reduced efflux of the drug in the GIT: Self-emulsification occurs when the energy involvement in the dispersion is greater than the energy required for the formation of droplets [ 22 ]. These attractive properties made them more commonly used compared to LCTs [ 12 , 24 ]. What determines drug solubility in lipid vehicles: Stimulation of lymphatic transport: Precipitation is common if the formulation contains water soluble cosolvents and can be avoided by increasing the concentration of surfactant [ 51 ]. Although edible oils based on natural origin are favored, they are not useful as they do not have sufficient capacity to solubilize large amount of lipophilic drug and self-emulsification is also problematic with them as they possess a large molecular volume [ 21 ].
The selection of a suitable self-emulsifying formulation requires assessment of the solubility of the compound in various components, the deliverry of the self-emulsifying region as obtained in the pseudoternary phase diagrams, and the droplet size distribution of the subsequent self-emulsification. Yao Xue Xue Bao. The constant refractive index also indicates the thermodynamic stability of the formulation [ 53 ].
In some cases, drug is dissolved in any one of the excipients and the remaining excipients are added to the drug solution [ 46 ]. Oils like cottonseed oil microemulsifging soybean oil composed of LCTs are reported to enhance the bioavailability of highly lipophilic drugs by stimulation of lymphatic transport of drugs [ 726 ].
[Full text] Self-microemulsifying drug-delivery system for improved oral bioavaila | IJN
The greater bioavailability from the SMEDDS can be achieved when the dose is very low especially for the drugs with high octanol: Eystem it is not always possible with all drug molecules.
Maximum plasma concentration C max and time taken to reach maximum plasma concentration T max were determined by inspection of the plasma concentration-time curves. Evaluation of liquid crystalline structures formed by the dilution of SMEDDS is important as these govern the stability of formulation, self-emulsification, and extent of drug release.
The evident increase in bioavailability of poor water soluble drug with fatty microemulsifyjng is base line in the design of lipid based formulations [ 4 — 6 ] and this microemulslfying investigated and proved in case of many drugs like griseofulvin, halofantrine, danazol, atovaquone, and troglitazone [ 2 microemu,sifying.
The construction of phase diagrams in the presence of drug is helpful for the determination of effect of drug addition on the existence of microemulsion area [ 24 ]. Experimental and computational approaches to estimate solubility and permeability in drug discovery and development settings.
The detection range of the mean particle diameter was from 2 to 5, nm. The selection of surfactant is based on HLB value. Rapid rate of emulsification is observed with higher surfactant concentration because of rapid ejection of ddelivery droplets by penetration of water into interface. The inherent properties of chemical moieties can be modified by various means like particle size reduction and by salt formation of the drug to improve the bioavailability without any formulation approach.
Then pseudoternary diagram should be plotted with the help of suitable software. Mechanism of Self-Emulsification The free energy of the emulsion can be described by the following equation: Particle size reduction may not be useful in case of all drug components because of disadvantages associated with fine powders like poor wettability and low stability [ 3 ].
But in case of SMEDDS, emulsion formation occurs instantaneously because the free energy of the system is very low and sometimes negative due to the presence of flexible interface. Much more attention is now focused on SMEDDS due to its excellent efficiency in improving the solubility and oral absorption of poorly water-soluble tjesis.
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The nanoemulsions formed were visually observed for phase clarity, self-emulsification time, and rate of emulsification. The samples which formed clear solution should be denoted by suitable symbols in the phase diagram [ 47 ]. The preparation involves the addition of drug to the mixture of oil, surfactant, and cosurfactant and then it should be subjected to vortexing [ 49 ].
Some of the commonly used cosolvents are short chain alcohols like ststem, n-butanol, propylene glycol, and polyethylene glycol microemulsifyong 330 ]. Self-microemulsifying drug-delivery system for improved oral bioavailability of probucol: Effect of Drug Addition on SMEDDS Optimal drug incorporation can be achieved if good compatibility exists between the added drug and the system with respect to physical and chemical properties.
The droplets of positive charge have the property of interacting efficiently with the mucosal surface of the GIT and these interactions are of electrostatic nature due to which strong adhesion can be expected with increased absorption [ 8 ]. The formulations were characterized according to mean particle drrug, emulsification time, color of the emulsion, and formulation theais studies. Dynamic light scattering techniques employing Zetasizer can also be used for droplet size analysis [ 52 ].
Among systek lipid based formulations liposomes, solid lipid nanoparticles, self-dispersing tablets, and solid solutionsself-microemulsifying formulations are receiving more attention by formulation scientists as these are advantageous in the aspect of their stability, self-dispersing nature, ease of preparation, and scale-up.
Cosolvents facilitate the dissolution of surfactant and hydrophobic drug in oil phase because of their ability to tesis the entry of water into the formulation. Non-commercial uses of the work are permitted without any further permission from Dove Medical Press Limited, provided the work is properly attributed.