Microparticles, controlled release formulations

Lamprecht A, Torres HR, Schafer U et al (2000) Biodegradable microparticles as a two-drug controlled release formulation a potential treatment of inflammatory bowel disease. J Control Release 69 445 54... 

A number of patented technologies for multiparticulate dosage forms have been described recently, such as the Micropump system, which is an osmotically driven coated microparticle system designed to increase the absorption time for rapidly absorbed drugs.59 Combination of water-soluble and water-insoluble polymers could provide enhanced controlled release rates and profiles. A patented technology (COSRx) has been reported to be capable of delivering various sophisticated release profiles. The formulation involves a guar-gum-based tablet and a combination of water-soluble and water-insoluble polymeric tablet coat.60... 

Singh M, Shirley B, Bajwa K, Samra E, Hora M, O Hagan D (2001) Controlled release of recombinant insulin-like growth factor from a novel formulation of polylactide-co-gly-colide microparticles. J Control Release 70 21-28... 

Microparticles and nanoparticles present some advantageous features, namely mucoadhesive properties. They have demonstrated some potential in vaginal drug delivery, particularly in the formulation of delivery systems for vaccines or peptides and proteins [160, 161], Nonetheless, these particles have to be incorporated in adequate carrier systems in order to be delivered. This task has been shown to be complex, it being hard to achieve controlled-release and steady-release profiles. 

Little, S. R. Lynn, D. M. Puram, S. V Longer, R. Formulation and characterization of poly(P-amino ester) microparticles for genetic vaccine delivery. J. Control. Release 2005, 107, 449-462. 

Kim SJ, Hahn SK, Kim MJ, et al. Development of a novel sustained release formulation of recombinant human growth hormone using sodium hyaluronate microparticles. J Control Release 2005 104 323-335. 

Tinsley-Bown AM, Fretwell R, Dowsett AB, Davis SL, Farrar GH. Formulation of poly(D,L-lactic-co-glycolic acid) microparticles for rapid plasmid DNA delivery. Journal of Controlled Release. May 15, 2000 66(2-3) 229-241. PubMed PMID 10742583. 

Rafati H, Coombes AG, Adler J, Holland J, Davis SS. Protein-loaded poly(DL-lactide-co-glycolide) microparticles for oral administration Formulation, structural and release characteristics. Journal of Controlled Release. 1997 43 89-102. 

Laurent P., Mike R., Coralie G., Jean-Marie D., Franc O., and Philippe L. New solid lipid microparticles for controlled ibuprofen release Formulation and characterization study. Int. J. Pharm. 422 (2012) 59-67. 

Microparticles. Size matters release rates depend on surface area, ie, a function of the square of the radius of a spherical particle, and thus larger particles release for longer and are able to manipulate the external availability of the pesticide. Small microparticles are therefore limited in their scope for controlling release but can be used in traditional spraying of dispersions onto soils and crops as well as for seed dressing. Suspension concentrate formulations of matrix microparticles have been developed based on various rosins, phenoUc resins, waxes, and bitumens. These have focused on lipophilic pesticides such as trifluralin and chlorpyrifos and reductions in volatility have been demonstrated (43). 

Details are given of the synthesis of a new family of ether-anhydride copolymers for use in controlled release drug formulations for inhalation. Microparticles containing model drugs were made with sizes suitable for deposition in various regions of the lung following inhalation as a dry powder. 50 refs. 

A variety of different formulations for controlled release polymers exist including microparticles, microcapsules and microspheres. Microparticles range in size from 1-200 pm, while particles with a diameter smaller than 1 pm are called nanoparticles. Microcapsules are microparticles which have the substance of interest enclosed in a shell of degradable polymer. Microcapsules however are characterized by a relatively fast release of large amounts of the enclosed substance. Microspheres (Figi 1), on the other hand, are monolithic in structure, Le. have the substance unifomdy distributed within the polymer layer. This distribution results in a more uniform release over longer periods of time. We selected such microspheies prepared from poly(lactide-glycolide) copolymers to develop our sensors. 

Rafati, H., Coombes, A.G.A., Adler, J., Holland, J., Davis, S.S., 1997. Protein-loaded PLGA microparticles for oral administration formulation, structural and release characteristics. Journal of Controlled Release 43, 89-102. 

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