PLA microspheres

Montisci, M.J., et al. 2001. Gastrointestinal transit and mucoadhesion of colloidal suspensions of Lycopersicon esculentum L. and Lotus tetragonabolus lectin-PLA microsphere conjugates in rats. Pharm Res 18 829. 

E. A. Poyner, H. O. Alpar, A. J. Almeida, M. D. Gamble, and M. R. Brown, Comparative study on the pulmonary delivery of tobramycin encapsulated into liposomes and PLA microspheres following intravenous and endotracheal delivery, J. Contr. Rel. 41 (1995). 

Bodmeier, R. McGinity, J.W. Solvent selection in the preparation of PLA microspheres prepared by the solvent evaporation method. Int. J. Pharm. 1988, 43, 179-186. 

Ruan, G. Feng, S.-S. Preparation and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) microspheres for controlled release of paclitaxel. Biomaterials 2003, 24, 5037-5044. 

Other attempts have focused on intravitreal injections of a suspension of polylactic acid (PLA) microspheres. Moritera et al. (70) showed that in vitro PLA microspheres containing 1% adriamycin (doxorubicin) can give sustained, first-order release for approximately two weeks. 

In the anhydrous microencapsulation, protein and excipients were suspended/dissolved in PLA/acetonitrile solution and then added to cottonseed oil to form an o/o emulsion with Span 85 as an emulsifier. Petroleum ether was then added to extract the acetonitrile and the microspheres were hardened. The microspheres were then recovered by filtration and dried under vacuum. As shown in Table 5 and Fig. 5, without the pore-forming PEG, only 36% BSA was released from PLA microspheres in 1-month of incubation with a total recovery (released-fall soluble and aggregated residue in polymer after release) of 76%. Blending in 30% of 35 kDa PEG with the PLA eliminated the BSA aggregation in polymer completely, with 82% of encapsulated BSA released in 1 month. The improved BSA stability in PLA/PEG microspheres could be attributed to a less acidic and more hydrophilic microenvironment in the polymer. As seen in Fig. 6, unlike PLGA 50/50, which caused a dramatic pH drop in the release medium after a 4-week incubation (41), a relatively neutral pH was retained in the release medium for both PLA and PLA/PEG microspheres. A slightly lower pH in the release medium incubated with PLA/PEG microspheres relative to that in PLA was also... 

Uchida T, Yoshida K, Ninomiya A, Goto S. Optimization of preparative conditions for polylac-tide (PLA) microspheres containing ovalbumin. Chemical and Pharmaceutical Bulletin. September 1995 43(9) 1569-1573. PubMed PMID 7586084. 

Secondary ion images of a PLA microsphere at different stages of FiB sample preparation (a) top view of ion-miiied trenches, scaie bar is 15. im and (b) fully undercut sample, scale bar is 10 m. 

The biggest success of pol5mier controlled release systems in cancer therapy however has been in the area of prostate cancer treatment. This therapy is luiique since it uses a hormone-suppressant rather than a chemotherapeutic agent to minimize cancer cell growth in the prostate. Several products include Lupron Depot (TAP Pharmaceuticals), Zoladex (Astra-Zeneca), and Trelstar Depot (Debio RP, Pharmacia). Lupron Depot involves PLA microspheres, Zoladex formulation is an extruded rod, whereas Trelstar depot consists of PLGA microspheres, all of which incorporate LHRH analogues. 

K.N. Nikou, et ah, A HER-2/neu peptide admixed with PLA microspheres induces a Thl-biased immune response in mice. Biochimica et Biophysica Acta (BBA) - General Subjects, 1725 (2) 182-189, 2005. 

Optical microscopy Size of PLA microspheres containing 5 wt% and 10 wt% of IL-2 and their size distributions were examined using an optical microscope (Olympus PM-IOAK, Japan). 

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