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Vesicular systems have been realized as extremely useful carrier systems in various scientific domains. Over the years, vesicular systems have been investigated as a major drug delivery system, due to their flexibility to be tailored for varied desirable purposes. In spite of certain drawbacks, the vesicular delivery systems still play an important role in the selective targeting, and the controlled delivery of various drugs. Researchers all over the world continue to put in their efforts in improving the vesicular system by making them steady in nature, in order to prevent leaching of contents, oxidation, and their uptake by natural defense mechanisms.

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  1. 1. ASeminar onPharmacosomesBy :-VINEET GUPTAAIPER,INDORE
  3. 3. INTRODUCTION:Pharmacosomes are the colloidal dispersions of drugs covalently bound to lipids,and may exist as ultrafine vesicular, micellar, or hexagonal aggregates, dependingon the chemical structure of drug-lipid complex.Pharmacosomes are amphiphilic phospholipid complexes of drugs bearing activehydrogen that bind to phospholipids.Pharmacosomes impart better biopharmaceutical properties to the drug, resultingin improved bioavailability.Pharmacosomes have been prepared for various non-steroidal anti-inflammatorydrugs, proteins, cardiovascular and antineoplastic drugs.Developing the pharmacosomes of the drugs has been found to improve theabsorption and minimize the gastrointestinal toxicity.  
  4. 4. IMPORTANCE:Pharamcosomes have some importance in escaping the tedious steps of removingthe free unentrapped drug from the formulation.Pharmacosomes provide an efficient method for delivery of drug directly to the site ofinfection, leading to reduction of drug toxicity with no adverse effects and also reducesthe cost of therapy by improved bioavailability of medication, especially in case ofpoorly soluble drugs.Pharmacosomes are suitable for incorporating both hydrophilic and lipophilic drugs.Entrapment efficiency is not only high but predetermined, because drug itself inconjugation with lipids forms vesicles.There is no need of following the tedious, time-consuming step for removing the free,unentrapped drug from the formulation.Since the drug is covalently linked, loss due to leakage of drug, does not take place.No problem of drug incorporationEncaptured volume and drug-bilayer interactions do not influence entrapmentefficiency, in case of pharmacosomes.
  5. 5. In pharmacosomes, membrane fluidity depends upon the phase transitiontemperature of the drug lipid complex, but it does not affect release rate since thedrug is covalently bound.The drug is released from pharmacosome by hydrolysis (including enzymatic).The physicochemical stability of the pharmacosome depends upon thephysicochemical properties of the drug-lipid complex.Following absorption, their degradation velocity into active drug molecule dependsto a great extent on the size and functional groups of drug molecule, the chain lengthof the lipids, and the spacer.They can be given orally, topically, extra-or intravascularly.
  6. 6. PREPARATION:Two methods have been used to prepare vesicles:1. The hand-shaking method2. The ether-injection methodIn the hand-shaking method, the dried film of the drug–lipid complex (with orwithout egg lecithin) is deposited in a round-bottom flask and upon hydration withaqueous medium, readily gives a vesicular suspension.In the ether-injection method, an organic solution of the drug–lipid complex isinjected slowly into the hot aqueous medium, wherein the vesicles are readilyformed.
  7. 7. FORMULATION OF PHARMACOSOMES:Drug salt was converted into the acid form to provide an active hydrogen sitefor complexation.Drug acid was prepared by acidification of an aqueous solutionof drug salt, extraction into chloroform, and subsequent recrystallization.Drug -PC complex was prepared by associating drug acid with an equimolarconcentration of PC.The equimolar concentration of PC and drug acid were placed in a 100-mLround bottom flask and dissolved in dichloromethane.The solvent was evaporated under vacuum at 40°C in a rotary vacuumevaporator.The pharmacosomes were collected as the dried residue and placed in avacuum desiccator overnight and then subjected to characterization.
  8. 8. EVALUATION OF PHARMACOSOMES: Pharmacosomes are evaluated for thefollowing parameters.Solubility:To determine the change in solubility due to complexation, solubility of drug acid and drug-PCcomplex was determined in pH 6.8 phosphate buffer and n-octanol by the shake-flask method.Drug acid (50 mg) (and 50 mg equivalent in case of complex) was placed in a 100-mL conicalflask. Phosphate buffer pH 6.8 (50 mL) was added and then stirred for 15 minutes.The suspension was then transferred to a 250 mL separating funnel with 50 mL n-octanol andwas shaken well for 30 minutes.Then the separating funnel was kept still for about 30 minutes. Concentration of the drug wasdetermined from the aqueous layer spectrophotometrically at 276 nm.
  9. 9. Drug content:To determine the drug content in pharmacosomes of drug (e.g.: diclofenac-PC complex), acomplex equivalent to 50 mg diclofenac was weighed and added into a volumetric flask with100 mL of pH 6.8 phosphate buffer.Then the volumetric flask was stirred continuously for 24 h on a magnetic stirrer. At the endof 24 h, suitable dilutions were made and measured for the drug content at 276 nm UVspectrophotometrically.Scanning electron microscopy (SEM):To detect the surface morphology of the pharmacosomes, SEM of the complex wasrecorded on a scanning electron microscope.
  10. 10. Differential scanning calorimetry (DSC):Thermograms of drug acid, phosphatidylcholine (80 %) and the drug -PC complex wererecorded using a 2910 Modulated Differential Scanning Calorimeter V4.4E (TA Instruments,USA).The thermal behavior was studied by heating 2.0 ± 0.2 mg of each individual sample in acovered sample pan under nitrogen gas flow. The investigations were carried out over thetemperature range 25–250 °C at a heating rate of 10 °C min–1.X-ray powder diffraction (XRPD):The crystalline state of drug in the different samples was evaluated usingX-ray powder diffraction. Diffraction patterns were obtained on a Bruker Axs- D8 DiscoverPowder X-ray diffractometer, Germany.The X-ray generator was operated at 40 kV tube voltages and 40 mA tube current, usinglines of copper as the radiation source. The scanning angle ranged from 1 to 60° of 2q in thestep scan mode (step width 0.4° min–1).Drug acid, phosphatidylcholine 80 % (Lipoid S-80) and the prepared complex wereanalyzed.
  11. 11. Dissolution study:In vitro dissolution studies of drug –PC complex as well as plain diclofenac acidwere performed in triplicate in a USP (8) six station dissolution test apparatus, type II(Veego Model No. 6 DR, India) at 100 rpm and at 37 °C.An accurately weighed amount of the complex equivalent to 100 mg of drug acid was putinto 900 mL of pH 6.8 phosphate buffer.Samples (3 mL each) of dissolution fluid were withdrawn at different intervals andreplaced with an equal volume of fresh medium to maintain sink conditions.Withdrawn samples were filtered (through a 0.45-mm membrane filter), dilutedsuitably and then analyzed spectrophotometrically at 276 nm.
  12. 12. APPLICATIONS:The approach has successfully improved the therapeutic performance ofvarious drugs i.e. pindolol maleate, bupranolol hydrochloride, taxol, acyclovir,etc.The phase transition temperature of pharmacosomes in the vesicular andMicellar state could have significant influence on their interaction withmembranes.Pharmacosomes can interact with bimembranes enabling a better transfer ofactive ingredient. This interaction leads to change in phase transitiontemperature of bimembranes thereby improving the membrane fluidityleading to enhance permeations.
  13. 13. CONCLUSION:Vesicular systems have been realized as extremely useful carrier systems in variousscientific domains. Over the years, vesicular systems have been investigated as amajor drug delivery system, due to their flexibility to be tailored for varied desirablepurposes. In spite of certain drawbacks, the vesicular delivery systems still play animportant role in the selective targeting, and the controlled delivery of various drugs.Researchers all over the world continue to put in their efforts in improving thevesicular system by making them steady in nature, in order to prevent leaching ofcontents, oxidation, and their uptake by natural defense mechanisms.
  14. 14. References:1.Y. Jin et al., "Self-Assembled Drug Delivery Systems-Properties and In Vitro –InVivo Behaviour of Acyclovir Self-Assembled Nanoparticles (san)," Int. J. Pharm.309 (1–2), 199–207 (2006).2. P. Goyal et al., "Liposomal Drug Delivery Systems: Clinical Applications," ActaPharm. 55, 1–25 (2005).3. H.A. Lieberman, M.M. Rieger, and G.S. Banker, Pharmaceutical Dosage Forms:Disperse Systems (Informa Healthcare, London, England, 1998), p. 163.4. S.S. Biju et al., "Vesicular Systems: An Overview," Ind. Jour. Pharm. Sci. 68 (2),141–153 (2006).5. M.O. Vaizoglu and P.P. Speiser, "Pharmacosomes—A Novel Drug DeliverySystem," Acta Pharm. Suec. 23, 163–172 (1986).6. A. Singh and R. Jain, "Targeted Vesicular Constructs For Cytoprotection andTreatment of H. Pylori Infections," US Patent 6576,625 (2003).
  15. 15. 7. I.P. Kaur and M. Kanwar, "Ocular Preparations: The Formulation Approach," Drug Dev.Ind. Pharm. 28 (5), 473–493 (2002).8. F. Volkering et al., "Influence of Nonionic Surfactants on Bioavailability andBiodegradation of Polycyclic Aromatic Hydrocarbons," App. Environ. Micro. 61 (5), 1699–1705 (1995).9. A. Steve, "Lipophilic Drug Derivatives for Use in Liposomes," US Patent 5534499(1996).
  16. 16. THANK YOU