SEMINAR ON SELF EMULSIFYING DRUG DELIVERY SYSTEM BY J.NAGARAJU M.PHARMACY II SEMESTER 2010 DEPARTMENT OF PHARMACEUTICS, UNIVERSITY COLLEGE OF PHARMACEUTICAL SCIENCES, KAKATIYA UNIVERSITY, WARANGAL.
1 CONTENTS INTRODUCTION DEFINITION AND ADVANTAGES FORMULATION OF SEDDS PREPARATION OF SEDDS MECHANISM OF SELF EMULSIFICATION IN VITRO EVALUATION OF SEDDS IMPROVEMENT OF ORAL ABSORPTION BY SEDDS APPLICATIONS OF SEDDS SOLID SEDDS RECENT APPROACHES IN SEDDS CONCLUSION REFERENCES
2 INTRODUCTION Oral route is the easiest and most convenient route for non invasive administration. Approximately 40% of new chemical drug moieties have poor aqueous solubility and it is a major challenge to modern drug delivery system. To overcome these problems, various formulations strategies are exploited
including the use of surfactant, lipid permeation enhancers, micronisation, salt formation, cyclodextrins, nanoparticles and solid dispersions. The concept of SEDDS for pharmaceutical purpose was initially developed by the Group of Groves (Dunkan QM et al., 2000, Fernando- Warnkulasuriya GLP et al., 1981). 3 BIOPHARMACEUTICAL CLASSIFICATION OF DRUGS 4 DEFINITION: SEDDS or self-emulsifying oil formulations (SEOP) are defined as isotropic mixtures of natural or synthetic oils, solid or liquid surfactants and
co-solvents/surfactants. SEDDSs emulsify spontaneously to produce fine oil in- water emulsions when introduced into an aqueous phase under gentle agitation and spread readily in the gastro intestinal tract. SEDDSs typically produce emulsions with a droplet size between 100300 nm while self-micro-emulsifying drug delivery systems (SMEDDSs) form transparent micro-emulsions with a droplet size of less than 50 nm. 5 ADVANTAGES OF SEDDS Protection of sensitive drug substances More consistent drug absorption, Selective targeting of drugs toward specific absorption window in
GIT Protection of drug(s) from the gut environment. Control of delivery profile Reduced variability including food effects Enhanced oral bioavailability enabling reduction in dose High drug loading efficiency. 6 For both liquid and solid dosage forms. These dosage forms reduce the gastric irritation produced by drugs. Emulsion are sensitive and metastable dispersed forms while S(M)EDDS are physically stable formulation that are easy to manufacture. As compared with oily solutions, they provide a large interfacial area for
partitioning of the drug between oil and water. DRAWBACK OF SEDDS: Lack of good in vitro models for assessment of the formulations for SEDDS. The traditional dissolution methods does not work, because these formulations potentially are dependent on digestion prior to release of the drug. 7 CLASSIFICATION OF LIPID FORMULATION SYSTEMS 8 Why we need SEDDS ?
9 COMPOSITION OF SEDDS Oils Surfactants Cosolvents / cosurfactants polymers 10 OILS: Oils are the most important excipient because oils can solubilize the lipophilic drug in a specific amount. Both long-chain triglyceride and medium-chain triglyceride oils with different degrees of saturation have been used for the formulation of SEDDSs.
Unmodified edible oils have poor ability to dissolve large amount of hydrophilic drugs. Modified or hydrolyzed vegetable or edible oils have contributed widely to the success of SEDDSs owing to their formulation and physiological advantages. 11 MCTs were preferred in the earlier self-emulsifying Formulations. Because of higher Fluidity, better solubility properties and self-emulsification ability, but evidently, they are considered less attractive compared to the novel semisynthetic medium chain derivatives. The absorption enhancement is greater when using unsaturated fatty acids. Very polar or nonpolar oils tend to form poor emulsion. Miglyol-812 and 840 with intermediate polarity have shown favorable emulsification properties
with tween 85. 12 LIPID INGREDIENTS Corn oil mono,di,tri-glycerides DL-alpha-Tocopherol Fractionated triglyceride of coconut oil(medium-chain triglyceride) Fractionated triglyceride of palm seed oil(medium-chain triglyceride) Mixture of mono-and di- glycerides of caprylic/capric acid Medium chain mono-and di- glycerides Corn oil Olive oil Oleic acid Sesame oil
Hydrogenated soyabean oil Hydrogenated vegetable oils Soyabean oil Peanut oil Beeswax 13 SURFACTANTS Natural surfactants have limited ability to emulsify. Non ionic surfactants are less toxic when compared to ionic surfactants. The usual surfactant strength ranges between 3060% w/w of the formulation in order to form a stable SEDDS. Non-ionic surfactants with high hydrophiliclipophilic balance (HLB) values are used in formulation of SEDDS.
Surfactants are amphiphilic in nature and they can dissolve or solubilize relatively high amounts of hydrophobic drug compounds 14 Examples of surfactants: Polysorbate 20 (Tween 20) Polysorbate 80 (Tween 80) Sorbitan monooleate (Span 80) Polyoxy-35-castor oil(Cremophor RH40) Polyoxy-40- hydrogenated castor oil (Cremophor RH40) Polyoxyethylated glycerides (Labrafil M 2125 Cs) Polyoxyethlated oleic glycerides (Labrafil M1944 Cs) D-alpha Tocopheryl polyethylene glycol 1000 succinate (TPGS)
15 16 COSOLVENTS/COSURFACTANTS Cosolvents may help to dissolve large amounts of hydrophilic surfactants or the hydrophobic drug in the lipid base. These solvents sometimes play the role as co-surfactant in the microemulsion systems. Alcohol is not included in SEDDS/SMEDDS due to its migration. Drug release is increased with increasing concentration of cosurfactant in formulation.
17 Examples of cosolvents: Ethanol Propylene glycol Polyethylene glycol Polyoxyethylene Propylene carbonate Tetrahydrofurfuryl alcohol polyethylene glycol ether(Glycofurol) POLMERS: Polymres like hydroxy propyl methyl cellulose and ethyl cellulose are used in sustained / controlled release SEDDS. 18
PREPARATION OF SEDDS Accurately weighed amount of drug was placed in a glass vial, and oil, surfactant and cosurfactant were added. Then the components were mixed by gentle stirring and vortex mixing for 30 min. This mixture were heated at 40C on a magnetic stirrer, until drug was perfectly dissolved. The mixture was stored at room temperature until further use.
19 MECHANISM OF SELF EMULSIFICATION According to Reiss self-emulsification occurs when the entropy change that favors dispersion is greater than the energy required to increase the surface area of the dispersion. The free energy of a conventional emulsion formation is a direct function of the energy required to create a new surface between the two phases and can be described by equation Where, G is the free energy associated with the process (ignoring the free energy of mixing), N is the number of droplets of radius, r, and represents the interfacial energy. With time, the two phases of the emulsion will tend to separate, in order to reduce the interfacial area, and subsequently, the free energy
of the systems. 20 21 FACTORS EFFECTING SEDDS Nature of oil and surfactant pair. Surfactant concentration and surfactant/ cosurfactant ratio. Temperature at which self emulsification occur. Drugs which are administered at very high dose are not suitable for SEDDS unless they have extremely good solubility in at least one of the components of SEDDS, preferably lipophillic phase. The ability of SEDDS to maintain the drug in solubilised form is greatly influenced by the solubility of the drug in oil phase.
22 Polarity of the Lipid Phase: The polarity of the droplet is governed by the HLB, the chain length and degree of unsaturation of the fatty acid, the molecular weight of the hydrophilic portion and the concentration of the emulsifier. The polarity reflects the affinity of the drug for oil and/or water, and the type of forces formed. The high polarity will promote a rapid rate of release of the drug into the aqueous phase. The design of optimum SEDDS requires preformulation soubility and phase diagram studies.
23 IN VITRO EVALUATION OF SEDDS Droplet size analysis and zeta potential measurements Viscosity determination In vitro diffusion studies Thermodynamic stability studies Dispersibility test Drug content analysis Turbidimetric evaluation Refractive index and percent transmittance Electroconductivity studies 24 1. Droplet size and Zeta potential
measurements: Droplet size and zeta potential are measured by Zeta sizer 3000 HAS (malvern instruments , UK) able to measure size between 10 to 3000nm. 2.Viscosity determination: It is determined by brookfield vicsometer. 3.In vitro diffusion studies: This test is carried out by dialysis technique. Drug is placed in dialysis tube which is kept in USP dissolution apparatus II containing 900ml of dialysis medium at 370C and stirred at 100rpm. 25
3.Thermodynamic stability studies: The poor physical stability of the formulation can lead to phase separation of the excipient, which affects not only formulation performance, as well as visual appearance of formulation. Incompatibilities between the formulation and the gelatin capsules shell can lead to brittleness or deformation, delayed disintegration, or incomplete release of drug. For thermodynamic stability studies we have performed three main steps, they areHeating cooling cycle Centrifugation Freez thaw cycle 26 4.Dispersibility test :
The efficiency of self-emulsification of oral nano or micro emulsion is assessed by using a standard USP XXII dissolution apparatus 2 for dispersibility test. One millilitre of each formulation was added in 500 mL of water at 37 1 0C at 50 rpm. It passes the test If it is rapidly forming (within 1 min) nanoemulsion, having a clear or bluish appearance. Or If it is rapidly forming, slightly less clear emulsion, having a bluish white appearance. Or If it is fine milky emulsion that formed within 2 min. 5.Drug content:
It is measured by HPLC. 27 6.Refractive Index and Percent Transmittance: The refractive index of the system is measured by refractometer by putting a drop of solution on slide and it comparing it with water (1.333). The percent transmittance of the system is measured at particular wavelength using Uv spectrophotometer. 7.Electro Conductivity Study:
The electro conductivity of resultant system is measured by electro conductometer. In conventional SEDDSs, the charge on an oil droplet is negative due to presence of free fatty acids. 8.Turbidimetric Evaluation Nepheloturbidimetric evaluation is done to monitor the growth of emulsification. 28 IMPROVEMENT OF ORAL ABSORPTION BY SEDDS Inhibition of gastric motility caused by the presence of lipid phase of emulsion
might allow more time for dissolution and absorption of drug from lipid phase. Eg; griseofulvin Large surface area afford by emulsion may be a contributing factor to enhanced absorption of drugs. Mucosal permeability of drug is increased by lipids and surfactants and enhanced mesetri lymph flow may be responsible for drug absorption. Surfactants partition into the cell membrane and disrupt the structural organization of the lipid bilayer leading to permeation enhancement
29 ROLE OF LIPOLYSIS: 30 EFFECT OF P-GLYCOPROTEIN INHIBITION Bile salts, fatty acids, phospholipids, and surfactants were potent absorption enhancers and efflux-reducing agents. Also investigated the non-ionic surfactants, such as Tween 80, Pluronic P85, and Cremophor have the potential ability to reverse MDR caused by p-glycoprotein (P-gp) and multidrug resistance-associated proteins. TPGS (d-tocopheryl polyethylene glycol 1000 succinate) has been shown
to be an effective inhibitor of P-gp mediated drug resistance and has been used to enhance the bioavailability of CsA. 31 Inhibition of MDR-related pumps by various excipients has been proposed to occur due to Binding competition-Tween80 with vinca alkaloid ATP depletion-pluronic copolymer which sensitize MDR cells. Membrane perturbation-BRIJ30 ,MYRJ52 cause structural changes to lipid domains in plasma membrane. Paclitaxel formulated as sedds show improve in bioavailability due to Pgp inhibition by surfactants.
32 SUPERSATURABLE SEDDS: supersaturable(S-SEDDS) formulations, have been designed and developed to reduce the surfactant side-effects and achieve rapid absorption of poorly soluble drugs. Surpersaturation is intended to increase the thermodynamic activity to the drug beyond its solubility limit and, therefore, to result in an increased driving force for transit into and across the biological barrier. The S-SEDDS formulations contain a reduced level of surfactant and a polymeric precipitation inhibitor to yield and stabilize a drug in a temporarily supersaturated state. paclitaxel S-SEDDS formulation produces approximately a 10-fold higher
maximum concentration (Cmax) and a 5-fold higher oral bioavailability (F =9.5%). 33 POSITIVELY CHARGED SEDDS: A novel SEDDS, which results in positively charged dispersed oil droplets upon dilution with an aqueous phase, showed an increase in the oral bioavailability of progesterone in young female rats. More recently, it has been shown that the enhanced electrostatic interactions of positively charged droplets with the mucosal surface of the everted rat intestine are mainly responsible for the preferential uptake of the model drug cyclosporine A (CsA) from positively charged droplets .
34 APPLICATIONS OF SEDDS 1.Improvement in Solubility and Bioavailability: Ketoprofen,, it is a drug of choice for sustained release formulation but it has produce the gastric irritation during chronic therapy. Along with this due to its low solubility, ketoprofen shows incomplete release from sustained release formulations. This problem can be successfully overcome when Ketoprofen is presented in SEDDS formulation. This formulation enhanced bioavailability due to increase the solubility of drug and minimizes the gastric irritation. Also incorporation of gelling agent in SEDDS sustained the release of Ketoprofen. Tipranavir and Saquinavir sedd formulations has shown that two folder higher bioavailability.
35 Protection against Biodegradation: Many drugs are degraded in physiological system, may be because of acidic PH in stomach, enzymatic degradation or hydrolytic degradation etc. Such drugs when presented in the form of SEDDS can be well protected against these degradation processes as liquid crystalline phase in SEDDS might be an act as barrier between degradating environment and the drug . Acetylsalicylic acid (Log P = 1.2, Mw=180), a drug that degrades in the GI tract because it is readily hydrolyzed to salicylic acid in an acid environment . 36
The SEDDS formulation of GBE (Ginkgo biloba) was accordingly developed to increase the dissolution rate and thus improve oral absorption and acquire the reproducible blood-time profiles of the active components of GBE. Silybin, the principal component of a Carduus marianus extract, is known to be very effective in protecting liver cells. The SEDDS formulation provides a greatly increased level of in vivo bioavailability of silybin, the level being at least 4-fold higher than that achievable by conventional formulations. 37 SOLID SELF EMULSIFYING DRUG DELIVERY SYSTEMS SEDDS are usually limited to liquid dosage forms because many excipients used in SEDDS are not solids at room temperature.
They are frequently more effective alternatives to conventional liquid SEDDS. S-SEDDS focus on the incorporation of liquid/semisolid SE ingredients into powders/ nanoparticles by different solidification techniques. Solid SEDDS has the flexibility to develop into different solid dosage form for oral and parenteral administrations. 38 SOLIDIFICATION TECHNIQUES: spray-cooling, spray drying, adsorption onto solid carriers, melt granulation, melt extrusion,
super-critical fluid based methods and high pressure homogenization (to produce solid lipid nanoparticles (SLN) or nanostructured lipid carriers (NLC)). 39 DIFFERENT DOSAGE FORMS OF S-SEDDS: Dry emulsions Self emulsifying capsules Self emulsifying sustained/controlled release tablets Self emulsifying sustained/controlled release pellets Self emulsifying solid dispersions Self emulsifying beads Self emulsifying sustained/controlled release microspheres Self emulsifying nanoparticles
Self emulsifying implants Self emulsifying suppositories 40 RECENT APPROACHES IN SEDDS 41 MARKETED PRODUCTS OF SEEDS Drug Name Compound Dosage form
Gengraf Cyclosporine A/III Hard gelatin capsule Abbott Laboratories Immuno suppr 42 CONCLUSION SEDDSs are a promising approach for the formulation of liphophilic drugs and to improve the oral bioavailability of drugs with poor aqueous solubility. As alternatives for conventional forms, liquid SEDDS, S-SEDDS are superior
offering reduced production costs, simplified industrial manufacture, and improved stability as well as better patient compliance. Most importantly, S-SEDDS are very flexible for developing various solid dosage forms for oral and parenteral administration It appears that more drug products will be formulated as SEDDS in the very near future and these aspects are the major areas for future research into S-SEDDS. 43
REFERENCES 1. Pharmaceutical emulsions and suspensions, volume 105 by 2. 3. 4. 5. 6. 7. 8. 9. Francoise Nielloud, Gilberte Marti-Mestres.235-254,1998 International Journal of Pharmaceutical Sciences and Nanotechnology volume 1 july-sep 2008. Rajesh B.V.et al, Journal of Global Pharma Technology 2010;
2(3):47 to 55 Research Journal of Pharm. And Tech 1(4) oct-dec 2008. www.sphinxsai.com www.rjptonline.org www.ditonline.info www.aapsj.org www.scholarsresearchlibrary.com 44 11. R.N. Gursoy and S. Benita, "Self-emulsifying drug delivery systems for improved oral delivery of lipophilic drugs," Biomedicine and Pharmacotherapy 58, 2004, 173-182 12. Pouton CW. Formulation of self-emulsifying drug delivery systems. Adv Drug Del Rev 1997; 25: 47-58. 13. Aungst BJ. Novel formulation strategies for improving oral
bioavailability of drugs with poor membrane permeation or presystemic metabolism. J Pharm Sci 1993; 82: 979-87. 14. Charman SA, Charman WN, Rogge MC, Wilson TD, Dutko FJ and Pouton CW. Self-emulsifying systems: formulation and biological evaluation of an investigative lipophilic compound. Pharm. Res. 9: 8794(1992). 15. Groves MJ and Mustafa RMA. Measurement of the spontaneity of self-emulsifiable oils. J Pharm Pharmacol 26: 672-688(1974). 45 46
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