Poly(hydroxybutyrate-hydroxyvalerate) microspheres containing progesterone: Preparation, morphology and release properties

Abstract

The biodegradable polyesters, poly(hydroxybutyrate) (PHB) and poly(hydroxybutyrate-hydroxyvalerate) (PHBV) were investigated for use as sustained delivery carriers of a model drug, progesterone. Spherical microspheres containing the drug were prepared by an emulsion solvent-evaporation method with gelatin as an emulsifier. Methylene chloride as the polymer solvent yielded smoother microspheres than chloroform. The surface texture was also dependent upon the temperature of the preparation and polymer used. Surface crystals were observed when the drug loading was increased beyond 5 per cent w/w. Thermograms of the microspheres did not show an endotherm corresponding to the melting of the drug because the drug dissolved in the melted polymer while heating. The amount of residual solvent in the microspheres (gas chromatographic assay) ranged from 3.4 to 58.4 ppm and was dependent on the processing temperature, concentration of the polymer in the solvent and the polymer composition. In vitro release of the drug was slowest from microspheres made from copolymer containing 9 per cent hydroxyvalerate. A less porous microsphere matrix was formed by this copolymer.

PLGA and PHBV Microsphere Formulations and Solid-State Characterization: Possible Implications for Local Delivery of Fusidic Acid for the Treatment and Prevention of Orthopaedic Infections

“…50/50, 85/15, 100/0) and changes in initial drug loading (data not shown). Gangrade et al found that changing the emulsifying agents (PVA to gelatin) significantly altered the microspheres properties (44). However, in our study, changing the emulsifying agent from PVA to gelatin in the external aqueous phase during the fabrication process did not affect the phase separation of FA from PLGA.…”

“…Residual DCM was not measured in the final microsphere products of this study. However, using similar processing conditions, Gangrade et al have shown there was no detectable amount of residual DCM in the microspheres (43,44). FA-loaded PHBV microspheres were fabricated using the same procedures described above.…”

“…To examine the effects of different polymers on the microsphere morphologies, 30% (w/w) FA-loaded PLGA (50/50) and PLLA microspheres were fabricated in the same manner as described above. In addition, the effects of using a different emulsifying agent in the aqueous solution on the morphology of microspheres of 30% (w/w) FA-loaded PLGA (85/15) were studied using gelatin instead of PVA (44).…”

Poly(3-hydroxybutyrate-co-3- hydroxyvalerate) nanoparticles prepared by a miniemulsion/solvent evaporation technique: effect of phbv molar mass and concentration

“…PHBV belongs to the group of polyhydroxyalkanoates (PHAs), polyesters naturally synthesized by microorganisms and deposited intracellularly as insoluble spherical inclusions [Grage et al, 2009]. Its characteristics of biocompatibility and biodegradability make PHBV attractive for numerous applications in medicine, including drug delivery systems [Reis et al, 2006;Poletto et al, 2008;Grage et al, 2009;Franceschi et al, 2008;Gangrade and Price, 1991;Sendil et al, 1999]. PHBV is a more attractive polyester than PHB because it has a lower degree of crystallinitty and this property can be changed as a function of the hydroxyvalerate content [Modi et al, 2011].…”

Thermosensitive Microparticles Based on Unsaturated Esters of some Poly‐ and Oligosaccharides: Preparation, Characterization, Drug Inclusion and Release

“…The use of biodegradable hydrophobic polymers, [poly(lactic acid), poly(glycolic acid), poly(e-caprolactone), poly(hydroxy alkanoates)], [1][2][3][4][5] and later on amphiphilic polymers [poly(lactide-coglycolide), poly(lactide)-poly(ethylene glycol)] [6][7][8] appeared as a great promise. Obtaining of such systems requires, in most of the cases, aggressive conditions (organic solvents, high temperature, sonication etc), which may compromise the stability of the included molecules.…”