Poly acid PLGA microspheres

Fu, K., Pack, D.W., Klibanov, A.M., and Langer, R. (2000). Visual evidence of acidic environment within degrading poly(lactic-co-glycolic acid) (PLGA) microspheres. Pharmaceut. Res., 17, 100-106. 

Cleland JL, Mac A, Boyd B, Yang J, Duenas ET, Yeung D, Brooks D, Hsu C, Chu H, Mukku V, Jones AJ. The stability of recombinant human growth hormone in poly(lactic-co-glycolic acid) (PLGA) microspheres. Pharm Res 1997 14 420-425. 

Cleland, l.L. et al.. Recombinant human growth hormone poly(lactic-co-glycolic acid) (PLGA) microspheres provide a long lasting effect, /. Control. Release, 49,193,1997. 

Polymers with a molecular weight above 50,000 Da did not form uniform particles, and therefore L-poly(lactic acid) (L-PLA, Mw 2000), poly(lactic-co-gly-colic acid) (PLGA, 75 25, 15,000 Da), and PLGA (50 50, 23,000 Da) were chosen for further investigation. Only L-PLA showed good entrapment efficiencies (80% for triptorelin and >50% for leuprolide). PLGA failed to entrap more than 10% in both cases. In comparison, microspheres were produced that differ from the lipo-sphere preparation only in that the solid hydrophobic core of the lipospheres is stabilized by a monolayer of phospholipid molecules embedded in its surface. All liposphere particle diameters were smaller compared to those of the microspheres. 

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