Combining inkjet printing and amorphous nanonization to prepare personalized dosage forms of poorly-soluble drugs.

Inkjet printing of drug nanosuspension on edible porous substrates was carried out for the first time with the objective of preparing personalized dosage forms of poorly soluble drugs. Amorphous drug-polysaccharide nanoparticle complex (or drug nanoplex in short) was used as the nanosuspension ink, instead of the conventional crystalline nanodrug. The amorphous drug nanoplex exhibited low propensity to Ostwald ripening growth, high colloidal stability, and supersaturation generation capability making it ideal for printing. Nanoplexes of ciprofloxacin - a BCS Class IV compound - prepared by complexation with dextran sulfate were used as the nanosuspension ink at two different sizes (i.e. ≈265nm and 188nm). Inkjet printing was performed on cellulose substrate at 0.25% (w/v) nanosuspension concentration and 5% (w/v) polyethylene glycol. For both nanoplex sizes, the results indicated that the printed dose could be increased by increasing the number of droplets dispensed. However, exact correlations between the achievable dose and the number of droplets dispensed were not evident, which was likely caused by the spatial non-homogeneity in the nanosuspension concentration. Compared to the larger nanoplex, printed nanodrugs of the smaller nanoplex consistently exhibited higher payload with better batch-to-batch reproducibility (<6%). The maximum achievable payload was equal to ≈2.5µg/cm(2), which was multifold higher than that achieved had inkjet printing of ciprofloxacin solution been performed. Nevertheless, print substrate with higher liquid uptake capacity is needed to increase the payload nearer to the therapeutic dose. Lastly, the drug release and non-cytotoxicity of the printed nanodrug were successfully established in vitro.

Cost-effective alternative to nano-encapsulation: Amorphous curcumin-chitosan nanoparticle complex exhibiting high payload and supersaturation generation.

While the wide-ranging therapeutic activities of curcumin have been well established, its successful delivery to realize its true therapeutic potentials faces a major challenge due to its low oral bioavailability. Even though nano-encapsulation has been widely demonstrated to be effective in enhancing the bioavailability of curcumin, it is not without drawbacks (i.e. low payload and costly preparation). Herein we present a cost-effective bioavailability enhancement strategy of curcumin in the form of amorphous curcumin-chitosan nanoparticle complex (or curcumin nanoplex in short) exhibiting a high payload (>80%). The curcumin nanoplex was prepared by a simple yet highly efficient drug-polysaccharide complexation method that required only mixing of the curcumin and chitosan solutions under ambient condition. The effects of (1) pH and (2) charge ratio of chitosan to curcumin on the (i) physical characteristics of the nanoplex (i.e. size, colloidal stability and payload), (ii) complexation efficiency, and (iii) production yield were investigated from which the optimal preparation condition was determined. The nanoplex formation was found to favor low acidic pH and charge ratio below unity. At the optimal condition (i.e. pH 4.4. and charge ratio=0.8), stable curcumin nanoplex (≈260nm) was prepared at >90% complexation efficiency and ≈50% production yield. The amorphous state stability, colloidal stability, and in vitro non-cytotoxicity of the nanoplex were successfully established. The curcumin nanoplex produced prolonged supersaturation (3h) in the presence of hydroxypropyl methylcellulose (HPMC) at five times of the saturation solubility of curcumin. In addition, curcumin released from the nanoplex exhibited improved chemical stability owed to the presence of chitosan. Both results (i.e. high supersaturation and improved chemical stability) bode well for the ability of the curcumin nanoplex to enhance the bioavailability of curcumin clinically.

Preserving the supersaturation generation capability of amorphous drug-polysaccharide nanoparticle complex after freeze drying.

While the supersaturation generation capability of amorphous nanopharmaceuticals (NPs) in their aqueous suspension form has been well established, their supersaturation generation is adversely affected after drying. Herein we investigated the effects of freeze drying on the supersaturation generation capability of a new class of amorphous NPs referred to as drug nanoplex prepared and stabilized by electrostatic complexation of drug molecules with polysaccharides (dextran sulfate). Using ciprofloxacin as the model drug, two types of freeze-drying adjuvants were investigated, i.e., (1) highly water-soluble excipient (trehalose, mannitol), whose role was to prevent irreversible NPs aggregations upon drying, and (2) crystallization inhibitor (hydroxypropylmethylcellulose (HPMC)), whose role was to suppress crystallization of the dissolved drug and the remaining solid phase. The results showed that dual-adjuvant formulations (i.e. trehalose-HPMC and mannitol-HPMC) were required to preserve the supersaturation generation capability of the drug nanoplex suspension after drying. Freeze drying with only one adjuvant type, or incorporating HPMC as physical mixtures with the freeze-dried nanoplex, were ineffective in preserving the supersaturation. The dual-adjuvant formulations produced prolonged supersaturation levels over 240min at ≈6-8× of the saturation solubility with comparable area under the curve (AUC) in the concentration versus time plot as that exhibited by the suspension form.

Amorphous nanodrugs prepared by complexation with polysaccharides: carrageenan versus dextran sulfate.

Amorphous nanodrugs prepared by electrostatic complexation of drug molecules with oppositely charged polysaccharides represent a promising bioavailability enhancement strategy for poorly-soluble drugs owed to their high supersaturation generation capability and simple preparation. Using ciprofloxacin (CIP) as the model drug, we investigated the effects of using dextran sulfate (DXT) or carrageenan (CGN) on the (1) preparation efficiency, (2) physical characteristics, (3) supersaturation generation, (4) antimicrobial activity, and (5) cytotoxicity of the amorphous drug-polysaccharide nanoparticle complex (nanoplex) produced. Owing to the higher charge density and chain flexibility of DXT, coupled with the greater hydrophobicity of CGN, the CIP-DXT nanoplex exhibited superior preparation efficiency and larger size than the CIP-CGN nanoplex. Whereas the low solubility and high gelation tendency of CGN resulted in superior supersaturation generation capability for the CIP-DXT nanoplex. The non-cytotoxicity, antimicrobial activity, colloidal, and amorphous state stability were established for both nanoplexes, making them an ideal supersaturated drug delivery system.

Amorphization strategy affects the stability and supersaturation profile of amorphous drug nanoparticles.

Amorphous drug nanoparticles have recently emerged as a promising bioavailability enhancement strategy of poorly soluble drugs attributed to the high supersaturation solubility generated by the amorphous state and fast dissolution afforded by the nanoparticles. Herein we examine the effects of two amorphization strategies in the nanoscale, i.e., (1) molecular mobility restrictions and (2) high energy surface occupation, both by polymer excipient stabilizers, on the (i) morphology, (ii) colloidal stability, (iii) drug loading, (iv) amorphous state stability after three-month storage, and (v) in vitro supersaturation profiles, using itraconazole (ITZ) as the model drug. Drug-polyelectrolyte complexation is employed in the first strategy to prepare amorphous ITZ nanoparticles using dextran sulfate as the polyelectrolyte (ITZ nanoplex), while the second strategy employs pH-shift precipitation using hydroxypropylmethylcellulose as the surface stabilizer (nano-ITZ), with both strategies resulting in >90% ITZ utilization. Both amorphous ITZ nanoparticles share similar morphology (∼300 nm spheres) with the ITZ nanoplex exhibiting better colloidal stability, albeit at lower ITZ loading (65% versus 94%), due to the larger stabilizer amount used. The ITZ nanoplex also exhibits superior amorphous state stability, attributed to the ITZ molecular mobility restriction by electrostatic complexation with dextran sulfate. The higher stability, however, is obtained at the expense of slower supersaturation generation, which is maintained over a prolonged period, compared to the nano-ITZ. The present results signify the importance of selecting the optimal amorphization strategy, in addition to formulating the excipient stabilizers, to produce amorphous drug nanoparticles having the desired characteristics.

Controlled release of Lactobacillus rhamnosus biofilm probiotics from alginate-locust bean gum microcapsules.

Chitosan-coated alginate microcapsules containing high-density biofilm Lactobacillus rhamnosus have been previously shown to exhibit higher freeze drying- and thermal-tolerance than their planktonic counterparts. However, their cell release profile remains poor due to the capsules' susceptibility to the gastric environment. Herein the effects of adding locust bean (LB) and xanthan (XT) gums to alginate (AGN) capsules on the stress tolerance and cell release profiles in simulated gastrointestinal fluids are investigated. Compared to the AGN-only capsules, the AGN-LB capsules exhibit improved stress tolerance (i.e. ≈ 6x for freeze drying, 100x for thermotolerance, 10x for acid), whereas the AGN-XT capsules only improve the acid tolerance. Importantly, the AGN-LB capsules possess the optimal cell release profile with a majority of cells released in the simulated intestinal juice than in the gastric juice. The AGN-LB capsules' superiority is attributed to their stronger interaction with the chitosan coating and high swelling capacity, thus delaying their bulk dissolution.