Microsphere: A Novel Drug Delivery System

M. P. Chandak*et al. /International Journal of Pharmacy & Technology Available Online through www.ijptonline.com ISSN: 0975-766X CODEN: IJPTFI Research Article MICROSPHERE: A NOVEL DRUG DELIVERY SYSTEM R. R. Thenge, M. P. Chandak, V. S. Adhao Dr.Rajendra Gode College of Pharmacy, Malkapur-443101, Maharashtra, India. Email: [email protected] Received on: 15-02-2019 Accepted on: 24-03-2020 Abstract: Microspheres are normally free flowing powders contains proteins or synthetic polymers which has biodegradable in nature and having a particle size but 200-500 μm. Number of techniques for the preparation of microspheres offers a spread of opportunities to regulate aspects of drug administration and enhance the therapeutic efficacy of a drug. A neat controlled drug delivery system can overcome a number of problems of conventional therapy and enhance therapeutic efficacy of the drug. There are various approaches in delivering therapeutic substance to the target site in sustained and controlled release fashion. These are prepared by methods like Single emulsion, Double emulsion, Polymerization, Phase separation coacervation, Emulsion solvent evaporation and solvent diffusion. Microspheres are having wide selection of applications due to controlled and sustained release. Keywords: Microsphere, evaluation, Novel drug delivery system. Introduction: To obtain maximum therapeutic efficacy, it becomes necessary to deliver the agent to the target tissue within the optimal amount within the right period of your time there by causing little toxicity and minimal side effects. There are various approaches in delivering a therapeutic substance to the target site during a sustained controlled release fashion. One such approach is using microspheres as carriers for drugs. the event of latest delivery systems for the controlled release of medicine is one among the foremost interesting fields of research in pharmaceutical sciences.[1]A neat controlled drug delivery system can overcome a number of the issues of conventional therapy and enhance the therapeutic efficacy of a given drug. to get maximum therapeutic efficacy, it becomes necessary to deliver the agent to the target tissue within the IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31955 M. P. Chandak*et al. /International Journal of Pharmacy & Technology optimal amount within the right period of your time there by causing little toxicity and minimal side effects. There are various approaches in delivering a therapeutic substance to the target site during a sustained controlled release fashion. the method of targeting and site-specific delivery with absolute accuracy are often achieved by attaching bioactive molecule to liposome, bioerodible polymer, implants, monoclonal antibodies and various particulate. One such approach is using microspheres as carriers for drugs. Microsphere are often used for the controlled release of medicine, vaccines, antibiotics, and hormones. [2, Microspheres are defined as “Monolithic sphere or therapeutic agent distributed throughout the matrix 3] either as a molecular dispersion of particles” or are often defined as structure made from continuous phase of 1 or more miscible polymers during which drug particles are dispersed at the molecular or macroscopic level. Microspheres are small spherical particles, with diameters within the micrometer range (typically 1 μm to 1000 μm). Microspheres are sometimes mentioned as microparticles. Biodegradable synthetic polymers and modified natural products like starches, gums, proteins, fats and waxes. The natural polymers include albumin and gelatin, the synthetic polymer include poly carboxylic acid and polyglycolic acid.[4]Some of the issues of overcome by producing control drug delivery system which enhance the therapeutic efficacy of a given drug for obtain maximum therapeutic efficacy and minimum side effects it necessary to deliver the agent to the target tissue within the optimal amount. a spread of drug are used as drug carrier, including immunoglobulin’s serum proteins, liposome’s, microspheres, microcapsules, nanoparticles and even cells like erythrocytes.[5] Fig.1: PLGA Microsphere. History:[6] They were first reported in 1959 by Sidney Fox, K. Harada, and J. Kendrick who proposed that microspheres might represent a significant early stage in precellular evolution. It has been suggested that IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31956 M. P. Chandak*et al. /International Journal of Pharmacy & Technology their greater stability makes them a better proposition during this regard than coacervates. The concept of packaging materials within microsphere dates back to the 1930s with work of Bungenberg de jong and coworkers on entrapment of drugs within coacervates. The first commercial applications of encapsulation were by National Cash Register Company for the manufacture of carbonless copying paper in 1957. The technology and applications have advance over last several decades this technology use for medical, food, cosmetic, Agricultural, graphics, and household products industry. ADVANTAGES:[7] • For Taste and odour masking. • To delay the volatilization. • For Separation of incompatible substances. • For Improvement of flow properties of powders. • To extend the steadiness of the drug against the external conditions. • For Safe handling of toxic substances. • To enhance the solubility of water insoluble substances by incorporation dispersion of such Material in aqueous media. • To reduce the dose dumping potential compared to large implantable devices. • For conversion of oils and other liquids to solids for simple handling. DISADVANTAGES: [8] • The costs of the materials and processing of the controlled release preparation, are substantially above those of ordinary formulations. • The fate of polymer matrix and its effect on the environment. • The fate of polymer additives like plasticizers, stabilizers, antioxidants and fillers. • Reproducibility is a smaller amount. • Process conditions like change in temperature, pH, solvent addition, and evaporation/agitation may influence the steadiness of core particles to be encapsulated. • The environmental impact of the degradation products of the polymer matrix produced in response to heat, hydrolysis, oxidation, solar radiation or biological agents. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31957 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Methods of Preparations: Double emulsion technique: [11, 12, 13] This method of microspheres preparation involves the formation of the multiple emulsions or the double emulsion of type w/o/w and is best suited to aqueous soluble drugs, peptides, proteins and the vaccines. This method can be used with both the polymers. The aqueous protein solution is dispersed in a lipophilic organic continuous phase. The protein solution may contain the active substances Continuous phase is generally consisted of the polymer solution that eventually encapsulates of the protein containing in dispersed aqueous phase. The primary emulsion is subjected to the homogenization or the sonication before addition to the aqueous solution of the poly vinyl alcohol. This results in the formation of a double emulsion. The emulsion is then subjected to removal either by solvent evaporation or by solvent extraction method. A number of hydrophilic drugs like luteinizing hormone releasing hormone (LH-RH) agonist, vaccines, proteins and conventional molecules can be successfully incorporated into the microspheres using the method of double emulsion solvent evaporation/ extraction method. Fig. 2: Microspheres by Double Emulsion Technique. Single emulsion technique: [14, 15] The micro particulate carriers of natural polymers i.e. those of carbohydrates and proteins carbohydrates are prepared by single emulsion technique. The chemical cross linking agents used are as followings: • glutaraldehyde, • formaldehyde, • di acid chloride Heat denaturation is not suitable for heat sensitive substances. Chemical cross linking have disadvantage of excessive exposure of active pharmaceutical ingredient to chemicals if added at the time of manufacturing and then subjected to centrifugation, washing, separation. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31958 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Fig.3: Microspheres by Single Emulsion Technique. Polymerization techniques: [17,18] The polymerization techniques conventionally used for preparing the microspheres are mainly classified as: I. Normal polymerization II. Interfacial polymerization. Both are administered in liquid phase. Normal polymerization: It is administered by using different techniques as bulk, suspension, precipitation, emulsion and micellar polymerization methods. In bulk, a monomer or a composition of monomers alongside the initiator or catalyst is typically heated to initiate polymerization. Polymer so obtained may be moulded as microspheres. Drug loading could also be done during the polymerization process. Suspension polymerization also referred as bead or pearl polymerization. It is carried out by heating the monomer or composition of monomers as droplets dispersion in a continuous aqueous phase. Droplets can also contain an initiator and other additives. Emulsion polymerization deviates from suspension polymerization as due to the presence initiator within the aqueous phase, which afterwards diffuses to the surface of micelles. Bulk polymerization has merits of formation of pure polymers. Interfacial polymerization This involves the reaction of various monomers at the interface between the two immiscible liquids to form a film of polymer that essentially envelops the dispersed phase. Fig.4: Microsphere by Polymerization Technique (a) normal polymerization, (b) Interfecial Polymerization. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31959 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Spray drying and spray congealing: [19] These methods are supported drying of the mist of the polymer and drug within the air counting on the removal of the solvent or cooling of the answer the 2 processes are named spray drying and spray congealing. one among the main merits of the method is feasibility of process under aseptic conditions. Spray drying process is employed to encapsulate various penicillins. Thiamine mononitrate and sulpha ethylthiadizole are encapsulated during a composition of mono- and di glycerides of hexadecanoic acid and octadecanoic acid using spray congealing. Fig .5: Microspheres by Spraying Drying Technique. Phase separation or coacervation technique: [20] This method based on the principle of decreasing the solubility of the polymer in non-aqueous phase to affect the formation of polymer rich phase called the coacervates. Here, the drug particles are dispersed in the solution of the polymer and an incompatible polymer is then added to the system which makes first polymer to separate and engulfment of the drug particles. Addition of organic results in the solidification of polymer. Poly lactic acid (PLA) microspheres have been manufactures by this method by using butadiene as incompatible polymer. The process variables are very useful because the rate of achieving the coacervates denotes the distribution of the polymer film, the size of particles and agglomeration of the formed particles. The agglomeration must be avoided by continuous stirring of the suspension using an optimum speed stirrer because as the process of microspheres formation starts the formed polymerize globules start to stick and form the agglomerates. So, the process variables are critical as they control the kinetic of the particles because there is no defined state of equilibrium attainment. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31960 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Fig. 6: Phase separation coacervation technique. Solvent extraction: [21] Solvent evaporation method is employed for manufacturing of microparticles, involves removal of the organic phase by extraction of the or non-aqueous solvent. This method involves water miscible organic solvents as isopropanol. Organic phase is often removed by extraction with water. This process decreases the hardening time for the microspheres. One variation of the method involves direct incorporation of the drug or protein to polymer organic solution. Rate of solvent removal by extraction method depends on the temperature of water, ratio of emulsion volume to the water and solubility profile of polymer. Fig.7: Solvent extraction Method. Quasi emulsion or solvent diffusion:[22] A novel quasi-emulsion solvent diffusion method to manufacture the controlled release microspheres of drugs with acrylic polymers has been reported in the literature. Microsponges can be manufactured by a quasi-emulsion solvent diffusion method using an external phase containing distilled water and polyvinyl alcohol. The internal phase is consisting of drug, ethanol and polymer is added at an amount of 20% of the polymer in order to enhance plasticity. At first, the internal phase is manufactured at 60ºC and then added to the external phase at room temperature. After emulsification process, the mixture is continuously stirred for 2 hours. Then the mixture can be filtered to separate the microsponges. The product is then washed and dried by vacuum oven at 40ºC for a day. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31961 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Fig.8: Quasi emulsion solvent diffusion. Ionic Gelation Method:[23] In Ionic Gelation technique are two methods by which hydrogel beads can be generated using ionotropic gelation technique as fallow: 1) Internal gelation: These methods differ from one another within the source of the cross-linking ion. In one of the methods, the cross linker ion is positioned externally shown in (Fig. 10) where as in the other method, the cross linker ion is incorporated within the polymer solution in inactive form shown in (Fig.10) External cross- linking produced thinner films with smoother surface, greater matrix strength, stiffness and permeability than internally cross-linked films. 2) External Gelation: Externally cross-linked micro pellets were also capable of greater drug encapsulation efficiency and slower drug release rate. Their kind of natural and synthetic polymeric systems that are been investigated for the controlled release of drug. A variety of natural polymers and their derivatised products have been successfully employed in hydrogel system for various pharmaceutical applications. In this review the potential of sodium alginate and chitosan to make the highly cross-linked structure and its pharmaceutical applications is discussed. As compared to other natural polymers, sodium alginate and chitosan shows no variations in viscosity and hence produces more uniform gel structure which forms stronger cross-linked structure and more loading of entrapped material. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31962 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Fig.9: a) Internal and b) External Gelation technique. Evaluation of Microspheres: [24-39] Particle size and shape: The foremost widely used procedures to see microparticles are conventional light microscopy (LM) and scanning electron microscopy (SEM). Both are often wont to determine the form and outer structure of microparticles LM provides an impression over coating parameters just in case of double walled microspheres.The microspheres structures are often visualized before and after coating and therefore the change are often measured microscopically. SEM provides higher resolution in contrast to the LM. SEM allows investigations of the microspheres surfaces and after particles are cross-sectioned, it also can be used for the investigation of double walled systems. Conflocal fluorescence microscopy is used for the structure characterization of multiple walled microspheres. Laser light scattering and multi size coulter counter aside from instrumental methods, which may be used for the characterization of size, shape and morphology of the microspheres. Infrared Spectroscopy: FT-IR is used to figure out the degradation of the polymeric matrix of the carrier system. The surface of the microspheres is investigated measuring alternated total reflectance (ATR). The IR beam passing through the ATR cell reflected repeatedly through the sample to supply IR spectra mainly of surface material. The ATR FTIR provides information about the surface composition of the microspheres depending upon manufacturing procedures and conditions. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31963 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Differential Scanning Calorimetric (DSC): DSC analysis is to spot the compatibility study between the drug and excipients. The DSC analysis of pure drug, 1:1 physical mixture of drug and excipients were administered using mettler Toledo DSC 821. Samples (2-8 mg) were accurately weighed and heated in sealed aluminum pans at a rate of 100c/min between 0-3000C temperature ranges under nitrogen atmosphere. Density determination: The density of the microspheres is often measured by employing a multi volume pychnometer. Accurately weighed sample during a cup is placed into the multi volume pychnometer. Helium is introduced at a continuing pressure within the chamber and allowed to expand. This expansion leads to a decrease in pressure within the chamber. Two consecutive readings of reduction in pressure at different initial pressure are noted. From two pressure readings the quantity and hence the density of the microsphere carrier is decided. Percentage yield of microspheres: Dried microspheres were collected and weighed accurately. The percentage yield was then calculated using formula given below, % Yield = mass of microsphere obtained / total weight of drug & polymer X 100 Isoelectric point: The micro electrophoresis is an apparatus used to measure the electrophoretic mobility of microspheres from which the isoelectric point is often determined. The mean velocity at different P H values starting from 3-10 is calculated by measuring the time of particle movement over a distance of 1 mm. By using this data the electrical mobility of the particle can be determined. The electrophoretic mobility is often associated with surface contained charge, ionisable behaviour or ion absorption nature of the microspheres. Capture efficiency: The capture efficiency of the microspheres or the percent entrapment can be determined by allowing washed microspheres to lyses. The lysate is then subjected to the determination of active constituents as per monograph requirement. The percent encapsulation efficiency is calculated using following equation: % Entrapment = Actual content/Theoretical content x 100 Angle of contact: IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31964 M. P. Chandak*et al. /International Journal of Pharmacy & Technology The angle of contact is measured to see the wetting property of a small particulate carrier. It determines the character of microspheres in terms of hydrophilicity or property. This physical science property is particular to solid and full of the presence of the adsorbate part. The angle of contact is measured at the solid/air/water interface. The advancing and receding angle of contact area unit measured by putting a drop during a circular cell mounted higher than objective of inverted magnifier. Contact angle is measured at 200C at intervals a second of deposition of microspheres. Drug Release: In vitro methods: There is a need for experimental methods which permit the discharge characteristics and permeability of a drug through membrane to be determined. For this purpose, a number of in vitro and in vivo techniques have been reported. In vitro drug release studies have been employed as a top-quality control procedure in pharmaceutical production, in development etc. Sensitive and reproducible release data derived from physicochemical and hydro dynamically defined conditions are necessary. The influence of technologically defined conditions and difficulty in simulating in vivo conditions has led to development of a number of in vitro release methods for buckle formulations; however, no standard in vitro method has yet been developed. Different workers have used apparatus of varying designs and under varying conditions, depending on the shape and application of the dosage form developed. In vivo methods: Methods for studying the permeability of intact mucosa comprise of techniques that exploit the biological response of the organism locally or systemically and those that involve direct local measurement of uptake or accumulation of penetrants at the surface. Some of the earliest and simple studies of mucosal permeability utilized the systemic pharmacological effects produced by drugs after application to the oral mucosa. However, the most widely used methods include in vivo studies using animal models, buccal absorption tests, and perfusion chambers for studying drug permeability. Angle of contact: The angle of contact is measured to determine the wetting property of a micro particles. It determines the nature of microspheres in terms of hydrophilicity or hydrophobicity, and it is measured at the solid/air/water interface. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31965 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Beaker method: The dosage form in this technique is made to adhere at the bottom of the beaker containing the suitable medium and stirred consistently using overhead stirrer. Volume of the medium used in the literature for the studies varies from 50-500 ml and the stirrer speed form 60-300 rpm. Animal models: Animal models are used mainly for the screening of the series of compounds, investigating the mechanisms and usefulness of permeation enhancers or evaluating a set of formulations. A number of animal models have been reported in the literature, however, very few in vivo (animal). Animal models such as the dog, rats, rabbits, cat, hamster, pigs, and sheep have been reported. In general, the procedure involves anesthetizing the animal followed by administration of the dosage form. In case of rats, the oesophagus is ligated to prevent absorption pathways other than oral mucosa. At different time intervals, the blood is withdrawn and analyzed. Drug Formulated In the Form of Microsphere: Ref Sr no. Drug Type of microsphere Use No. 1 Aspirin Nano hydroxyapatite microsphere NSAID’S Activity 40 2 Cephalosporin Chitosan Microspheres Technique Antibacterial Activity 41 solvent evaporation /Diffusion Antitubercular Activity 42 3 Ciprofloxacin 43 microsphere Chloromphinic Chitosan Microspheres Broad spectrum ol HCl Technique Antibiotics Chlorhexidie Chitosan Microspheres Anti-microbial Activity 44 buccal tablets. Technique Cold Congelating Method of Antimalarial 45 microspheres. Activity Diclofenac biodegradable and biocompatible Treatment of arthritis sodium polymer microsphere 4 5 6 Chloroquinone 46 7 IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31966 M. P. Chandak*et al. /International Journal of Pharmacy & Technology Magnetic Dispersion Extraction 8 Antibiotics Activity 47 Antitubercular Activity 48 Hypertension Activity 49 Anticancer Activity 50 Biodegradable Type of Antibiotic of Chronic 51 Microsphere prostatitis Solvant Diffusion microsphere, Antitubercular Activity 52 Aminoglycoside 53 Doxycycline Method of microspheres Solvent Evaporation method of 9 Ethambutol Microsphere Losartan solvent evaporation /Diffusion Potassium microsphere. 10 Biodegradable Type of 11 Methotrexate Microsphere Ofloxacin 12 13 Rifamycin by Eudragid Polymer Albumin & Gelatin Microspheres 14 Streptomycin Antibiotics Sulfasalazine Pectin Gel Microspheres NSAID’S Activity 54 Biodegradable Type of Anti-microbial Activity 55 Antibiotics Activity 56 Antifungal activity 57 NSAID’S Activity 58 High ceiling loop 59 15 Potassium 16 Sulfonamides Microsphere Spray drying technique for Tetracycline 17 formation of polymers of HCl microsphere Solvent Evaporation method of 18 Tolnaftate Microsphere Diclofenac W/O/W double emulsion solvent Sodium evaporation method Furosemide Solvent Evaporation method of 19 20 IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31967 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 21 Paracetamol Microsphere Diuretic activity Ionotropic gelatin method Antipyretic activity 60 Applications: [27] • For Taste and odour masking. • To delay the volatilization. • For separation of incompatible substances. • For safe handling of toxic substances. • To increase the stability of the drug against the external condition. • To Improve the solubility of water insoluble substances by incorporating dispersion of such material in aqueous media. • To reduce the dose dumping potential compared to large implantable device. Conclusion: Microsphere is one of the recently used Novel Drug Delivery for a variety of Active pharmaceutical ingredients. It has been great potential for site specific / Targeted delivery of drug. The high molecular weight compounds such as Proteins and Peptides are formulated successfully in the form of Microsphere. Therefore microsphere has great potential as a “Novel Drug Delivery System”. References: 1. N. K. Jain, Controlled and Novel drug delivery, CBS Publishers New Delhi, India; 21(4) 236-237. 2. Y. W. Chein, Oral Drug Delivery Systems: In Novel drug delivery systems. Marcel Dekker, Inc., New York.1992;50:139-77. 3. Mathew Sam T., Devi Gayathri S., Prasanth V. V., Vinod B; NSAIDs as microspheres, The Internet J. of Pharma.2008;6(1):67-73. 4. Li, S.P., Kowalski C.R., Feld K.M., Grim W.M. Recent Advances in Microencapsulation Tech. and Equipment, Drug Dev Ind. Pharma.1988;14:353-76. 5. P.M. Dandagi, V.S. Mastiholimath, M.B. Patil, M.K. Gupta, Biodegradable micro particulate system of captopril. Int. J. Pharm. 2006; 307:83-88. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31968 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 6. N.K. Jain. Introduction to Novel drug delivery system, Vallabh Prakshan,177-193. 7. Sree Giri Prasad B., Gupta V. R. M., Devanna N., Jayasurya K., Microspheres as drug delivery system A Rev., JGTPS. 2014;5(3):1961-72. 8. Mohan M., Sujitha H., Dr. Rao V. U. M., Ashok M., Arun kumar B., A brief Rev on mucoadhesive microspheres, IJRRPAS. 2014;4(1):975-86. 9. Trivedi P. Verma A.M.L. Garud N, Preperation and Charecterization of Aceclofenac Microspheres, Asian J. Pharma.2008; 2(2):110-115. 10. Mathew Sam T., Devi Gayathri S., Prasanth V.V., Vinod B; NSAIDs as microspheres, The Int. J. of Pharma.2008; 6(1): 67 – 73. 11. Pradesh T.S., Sunny C.M., Varma K.H., Ramesh P., Preperation of microstuctured hydroxyapatite microspheres using oil in water emulsion, Bull Matter. Sci. 2005; 28(5):383-390. 12. Diane J. Burgress and Anthony J. Hickey, The University of North Carolina at Chapel Hill, Carolina, U.S. A, Encyclopedia of Pharma Tech, 2328 -2337. 13. Koff US patent (March21963) 3,080,292. 14. John P.M and Becker. C.H. J. Pharma. Sci.,1968;57: 584. 15. J.C. Sworbrik and J.C.Boylen (Ed), Marcel Dekker, New York (Basel), Encyclopedia of pharma Tech.1988;10:1 16. J.H Ratcliff, I.M Hunnyball, A. Smith and C.G Wilson. J. Pharmacol., 431-436. 17. Fujimoto S. and Miyazaki M. Biodegradable motomycin C microspheres, Given intraarterially for hepatic cancer,1984: 2404- 2410. 18. Improved patient compliance and comfort compared with intravenous administration Rapid absorption, higher bioavailability. 19. Davis S.S. and Illum L. Microspheres as drug carrier in drug carrier system, F.H Roerdink and A.M. Kron (Eds), John Wiley and sons Ltd.,1.1989 20. S.P. Vyas and R.K. khar “Targeted and Controlled Drug Delivery: Novel Carrier System CBS publication and distributors, New Delhi, 2002;1:81-121. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31969 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 21. J.C Sworbrik and J.C. Boylen (Ed), Marcel Dekker, New York (Basel), Encyclopedia of Pharma.Tech.,1988;10:1-29. 22. J.H Ratcliff, I.M Hunnyball, A. Smith and C.G Wilson, J. Pharmacol.1984;431-43 23. S. Fujimoto, M. Miyazaki et.al. Biodegradable motomycin C microspheres. Given intra arterially for hepatic cancer, 1985:2404-2410. 24. Schugens C. Larvelle. N. Nihantn., Grandfils C. Jerome R. and Teyssie. P. J.Control.Rel.1994;32:161. 25. Mathews B.R. and Nixon J.R. J. Pharma Pharmacrol.1974;26:283. 26. N.K. Jain, Advances in controlled & Novel drug delivery, 03 Edition, 71. 27. H.V.enkatesh “A buccal delivery system of Salbutamol Sulphate” M. Pharm; Budrinarayan, N. (1991) “Utilisation and Evaluation of plant products in pharmaceutical formulations”.M.Pharm.1989 28. Tanaka, W. Akito, E.Yoshida, K.Terada, T. and Ninomiya, H. “pharm preparations for oral cavity administration” US patent No.4059686;1977 29. Ishida, M. Nambu, N. and Nagai, T.“Highly viscous gel ointment containing carbapol for application to the oral mucosa”. Chem. Pharma Bull.,1983; 31:4561. 30. Yukimatsu, K. Nozaki, Y. Kakumoto, M.and Ohta, M.“Development of a transmucosal controlled release device for systemic delivery of antianginal drugs pharmacokinetics and pharmacodynamics”. Drug Dev. Ind. Pharma,1994; 20(4): 503534. 31. Hussain, M.A. Aungst, B.J. Kearney A. and Shefter, E.“Buccal and oral bioavailability of naloxone and naltrexone in rats”. Int. J. Pharma.,1987; 36:127. 32. Oh, C.K. and Ritschel., W.A. “Biopharmaceutical aspects of buccal absorption of insulin rabbits I. Effects of dose, size, Ph & sorption enhancers: in vivo in vitro correlation”. Pharma.Res.,1999; 5(5):100. 33. Oh, C.K. and Ritschel, W.A. “Biopharmaceutical aspects of buccal absorption of insulin in rabbits II. Absorption characteristics of insulin through the buccal mucosa”. pharma.Res.,1988;5(5):100. 34. Kellaway, I. W. andwarren, S.I. “Mucoadhesive hydrogels”. Proc. Intern. symp. Control. Rel. Bioact. Mater., 18:73. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31970 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 35. Ishida, M.: Nambu, N.and Nagai, T. “Highly viscous gel ointment containing carbopol for application to the oral mucosa”. Chem. pharm. Bull., 1983;31:4561. 36. Ishida, M. Nambu, N. and Nagai, T. “Ointment type oral mucosal dosage form of carbopol containing prednisolone for the treatment of aphtha”. Chem. Pharma. Bull.,1983;31:1010. 37. Hoogstrate, A.J, verhoef, J.C. Tuk., B. Pijpers, A. Vercheijden, J.H.M.; Jungiger, H.E. and Bodde, H.C. “Invivo buccal delivery of fluorescein iso thiocyanate – dextran 4400 with glycodeoxy cholate as an absorption enhacer in pigs”. J. Pharma. Sci.,1996; 85(5): 457-460. 38. Burnside, B.A; Keith, A.P. and snipes, W. “micro porous hollow fibers as a peptide delivery system via the buccal activity” proceed intersymp control RelBioact. mater,1989;16:94. 39. M.J. Rathon, “Human buccal absorption I.A method for Estimating the transfer kinetics of drugs W cross the human buccal membrane”. Int. J. Pharma.,1991; 69:103. 40. Sen Li, kaun wang, ming jong Preparation and evaluation of Nano hydeoxypeptide poly(sterinybenzene) porous microspheres, for aspirine carrier, Sci. of china chemistry.2012. 41. Carmen Mariana, Alexandru Mihal. Preparation and evaluation of antibacterial activity of Cephalosporins drug loaded in magnetic chitosan Microsphere. Int. J. pharma. 2012;202-205. 42. Shivshankae Hardenia, Ankit Jain, Formulation and evaluation of Mucoadhesive Microspheres from ciprofloxacin. Gaumal National Advance pharma education. 43. Xizhi shi, Sulin Zheng, Dabing Zheng. Preparation and evaluation of Broad-Spectrum antibiotics as chitosan microspheric method of polymer J. chromatography. 2011:24-30. 44. Elisabetta Gavinia, Massimo Cossua, Milena Sorrentib. Formulation and in vivo evaluation of chlorhexidine buccal tablets prepared using drug-loaded chitosan microspheres 2001. 45. Benna Saparia Formulation and evaluation of chloroquinone phosphate Microsphere by using cross linked gelatin for long term drug delivery, at Indian J. Res. 46. christina. e, jawaharlal nehru technological university, hyderabad Preparation of microspheres of diclofenac sodium by ionotropic gelation technique Int. J. pharmacy and pharm sci.2013;5(1):09751491. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31971 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 47. Li, yan Dong. Preparation of Doxicycline imprented magnetic microsphase by inverse emulsion, suspension, polymerization for magnetic dispersion extraction of tetracycline 2013. 48. Haw jang, Xiaoyang Pang, Preparation of sheu strecture of microsphere of biological safety. by Int. J. clinical experimental medicine. 49. T.S. keerthi, S.K. senthil kumar. Formulation and evaluation of microspheres of losartan potassium using biodegradable natural by Int. bulletin of drug Res:120-131. 50. R. Narayani & K. Panduranga Rao. Control release of anticancer drug Methotrexate from biodegreedable gelatin microspheres 67-77. 51. Jong yooon bahk, Jae seog Hyun. Concentration of ofloxacin in canine prostrate tissue after intraprostatic injections of biodegradable sustained release microsphere published by the US J. 123. 52. A.B. Nighute, S.B. Bhise Preparation & evaluation of microsphere of Refamycin eudragit polymers at Res. J. pharma.2009; 2: 680-686. 53. H. Gurkan, A. A. Hincal. Streptomycin sulphate microsphere formulation in vivo distribution J. of microencapsulations 2013; 3:101-109. 54. Yukimatsu, K. Nozaki, Y. Kakumoto, M. and Ohta, M. “Development of a transmucosal controlled release device for systemic delivery of antianginal drugs pharmacokinetics and pharmacodynamics”. Drug Dev. Ind. Pharma.1996;20(4):503534. 55. A. K. Das, Determination of physical state of drug in microcapsule and microphase formulation 2011:112-119. 56. S. S. Bansode, S. K. Banarjee, D. D. Gaikwad, S. L. Jadhav, R. M. Thorat: Microencapsulation A review, Int. J. Pharma Sci Rev. Res. 2010; 1(2):38-42. 57. P. Venkatesan, R. Manavalan and K. Valliappan: Microencapsulation: A vital technique in novel drug delivery system. J. Pharma Sci and Res. 2009;1(4):26-35. 58. Naveen Chella, Kiran Kumar Yada, Rashmi Vempati: Preparation and Evaluation of Ethyl Cellulose Microspheres containing Diclofenac Sodium by Novel W/O/O Emulsion Method. J. Pharma Sci. and Res.2010;2(12):884-88. IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31972 M. P. Chandak*et al. /International Journal of Pharmacy & Technology 59. Amitava Ghosh, L.K Nathi and Partha Roy: A study on the effect of different acrylic polymers on Frusemide loaded calcium alginate micropellets prepared by Ionotropic Gelation technique, Priory Medical J.2007. 60. Nethaji Ramalingam et al. Formulation and Evaluation of Paracetamol Loaded Mucoadhesive Microspheres. Int J Pharm Pharmacol 2017; 1(2): 106. Corresponding Author: M. P. Chandak*, Email: [email protected] IJPT| March-2020| Vol. 12 | Issue No.1 | 31955-31973 Page 31973