Nanoparticles formed by anti-solvent precipitation to produce redispersible and amorphous drug powders
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Anti-solvent precipitation produced sub-100 nm [Greek small letter beta]-carotene (BCN) particles despite only modest mixing energy. The particles were stabilized with poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (P407) and/or hydroxypropylmethylcellulose (HPMC E5) to increase the time scale for coagulation relative to the mixing time. However, this method could only produce itraconazole (ITZ) particles in the 250-300 nm range. The higher solubility of ITZ versus BCN promoted solute diffusion and thus, facilitated growth by Ostwald ripening. Anti-solvent precipitation was then used to produce nanoparticle suspensions of poorly water-soluble drugs in an amorphous state. The nanoparticles were recovered by flocculation with sodium sulfate, filtered and dried to form redispersible powders. The redispersed ITZ particle size of 300 nm and naproxen (NAP) particle size of 600 nm were comparable to the values in the aqueous suspension prior to flocculation, and consistent with primary particles observed by SEM. Dissolution of ITZ and danazol (DAN) particles in basic media yielded high supersaturation levels up to 16.9 times the ITZ equilibrium solubility or 5.9 times the DAN equilibrium solubility. The flocculated powders had calculated 4-hr areas under the curve (AUCs) 1.5-6 times higher than their lyophilized counterparts. The ability to produce and recover potent amorphous nanoparticles and to demonstrate these nanoparticles can generate high levels of supersaturation offer new opportunities for improving bioavailability of poorly water-soluble drugs.