Rheological blends for drug delivery. I. Characterization in vitro

Codelivery of metformin and methotrexate with optimized chitosan nanoparticles for synergistic triple-negative breast cancer therapy in vivo

The development of effective therapeutic strategies for triple-negative breast cancer (TNBC), an aggressive subtype with limited treatment options, remains a critical challenge. This study aimed to design and evaluate a combination therapy using chitosan nanoparticles (Cs NPs) loaded with metformin (Met) and methotrexate (MTX) as a promising approach for TNBC management. The Cs NPs exhibited an average size of 78.8 ± 25.84 nm for blank Cs NPs, 84.50 ± 22.54 nm for Met-Cs NPs, and 86.70 ± 30.90 nm for MTX-Cs NPs, with positive surface charges of 26.40 ± 1.40 mV, 28.20 ± 1.60 mV, and 14.30 ± 2.40 mV, respectively. The drug encapsulation efficiency was 88.56 ± 2.26 % for Met-Cs NPs and 97.03 ± 0.52 % for MTX-Cs NPs. The cellular uptake studies demonstrated a time-dependent increase in the accumulation of Shikonin-labeled Cs NPs in 4T1 cells. The cytotoxicity assays revealed that Met-Cs NPs and MTX-Cs NPs exhibited significantly lower IC50 values (19.85 μg/mL and 103.2 ng/mL, respectively) compared to the plain drugs at 48 h. The combination of Met-/MTX-Cs NPs showed a synergistic cytotoxic effect, inducing 50 % cell death at 15.233 μg/mL of Met and 0.166 μg/mL of MTX. In vivo studies using a 4T1 xenograft mouse model demonstrated that the combination of Met-/MTX-Cs NPs resulted in a 100 % reduction in initial tumor volume, compared to a 40 % decrease with the free drug combination. The tumor growth inhibition was 70.45 % for the Met-/MTX-Cs NPs group, significantly higher than the 33.86 % observed in the free drug combination group. The findings of this study highlight the potential of the Met-/MTX-Cs NPs combination as a novel and effective therapeutic approach for TNBC management. The enhanced therapeutic efficacy, improved safety profile, and the ability to modulate key signaling pathways make this nanoparticle-based combination therapy a promising candidate for further clinical investigation.

Hybrid Nanoparticle-Hydrogel Systems for Drug Delivery Depots and Other Biomedical Applications

Hydrogel-based depots typically tend to remain where injected and have excellent biocompatibility but are relatively poor at controlling drug release. Nanoparticles (NPs) typically have the opposite properties. The smaller the NPs are, the more likely they are to leave the site of injection. Their biocompatibility is variable depending on the material but can be poor. However, NPs can be good at controlling drug release. In these and other properties, combining NPs and hydrogels can leverage their advantages and negate their disadvantages. This review highlights the rationale for hybrid NP-hydrogel systems in drug delivery, the basic methods of producing them, and examples where combining the two systems addressed specific problems.

Biomaterials for non-invasive trans-tympanic drug delivery: requirements, recent advances and perspectives

Various non-invasive delivery systems have recently been developed as an alternative to conventional injections. Local transdermal administration represents the most attractive method due to the low systemic side effects, excellent ease of administration, and persistent drug release. The tympanic membrane (TM), a major barrier between the outer and middle ear, has a similar structure of the stratum corneum compared to the surface of the skin. After several attempts, non-invasive trans-tympanic drug delivery has been regarded as a promising option in the treatment of middle and inner ear diseases. The round window membrane (RWM) was a possible non-invasive delivery approach from the middle to inner ear. The improved permeability of nanocarriers crossing the RWM is a current hotspot in therapeutics for inner ear diseases. In this review, we include the latest studies exploring non-invasive trans-tympanic delivery to treat middle and inner ear diseases. Both passive and active delivery systems are described. A summary of the benefits and disadvantages of various delivery systems in clinical practice and production procedures is introduced. Finally, future possible approaches for its effective application as a non-invasive middle and inner ear drug delivery system are characterised.

Synergistic Polymer Blending Informs Efficient Terpolymer Design and Machine Learning Discerns Performance Trends for pDNA Delivery

Cationic polymers offer an alternative to viral vectors in nucleic acid delivery. However, the development of polymer vehicles capable of high transfection efficiency and minimal toxicity has remained elusive, and continued exploration of the vast design space is required. Traditional single polymer syntheses with large monomer bases are very time-intensive, limiting the speed at which new formulations are identified. In this work, we present an experimental method for the quick probing of the design space, utilizing a combinatorial set of 90 polymer blends, derived from 6 statistical copolymers, to deliver pDNA. This workflow facilitated rapid screening of polyplex compositions, successfully tailoring polyplex hydrophobicity, particle size, and payload binding affinity. This workflow identified blended polyplexes with high levels of transfection efficiency and cell viability relative to single copolymer controls and commercial JetPEI, indicating synergistic benefits from copolymer blending. Polyplex composition was coupled with biological outputs to guide the synthesis of single terpolymer vehicles, with high-performing polymers P10 and M20, providing superior transfection of HEK293T cells in serum-free and serum-containing media, respectively. Machine learning coupled with SHapley Additive exPlanations (SHAP) was used to identify polymer/polyplex attributes that most impact transfection efficiency, viability, and overall effective efficiency. Subsequent transfections on ARPE-19 and HDFn cells found that P10 and M20 were surpassed in performance by M10, contrasting with results in HEK293T cells. This cell type dependency reinforced the need to evaluate transfection conditions with multiple cell models to potentially identify moieties more beneficial to delivery in certain tissues. Overall, the workflow employed can be used to expedite the exploration of the polymer design space, bypassing extensive synthesis, and to develop improved polymer delivery vehicles more readily for nucleic acid therapies.

Co-formulations of adalimumab with hyaluronic acid / polyvinylpyrrolidone to combine intraarticular drug delivery and viscosupplementation

Polymer-based formulations present an attractive strategy in intraarticular drug-delivery to refrain biologicals from early leakage from the joint. In this study, co-formulations of hyaluronic acid and polyvinylpyrrolidone were investigated for their potential as viscosupplements and their influence on the transsynovial loss of adalimumab. For this purpose, polymer mixtures were evaluated for their viscosity and elasticity behavior while their influence on the permeation of adalimumab across a porcine ex-vivo synovial membrane was determined. Hyaluronic acid showed strong shear thinning behavior and exhibited high viscosity and elasticity at low motions, while combinations with polyvinylpyrrolidone provided absorption and stiffness at high mechanical stress, so that they can potentially restore the rheological properties of the synovial fluid over the range of joint motion. In addition, the formulations showed significant influence on transsynovial permeation kinetics of adalimumab and hyaluronic acid, which could be decelerated up to 5- and 3-fold, respectively. Besides viscosity effects, adalimumab was retained primarily by an electrostatic interaction with hyaluronic acid, as detected by isothermal calibration calorimetry. Furthermore, polymer-mediated stabilization of the antibody activity was detected. In summary, hyaluronic acid - polyvinylpyrrolidone combinations can be efficiently used to prolong the residence of adalimumab in the joint cavity while simultaneously supplying viscosupplementation.

Prevention of peritoneal adhesions using polymeric rheological blends

The effectiveness of rheological blends of high molecular weight hyaluronic acid (HA) and low molecular weight hydroxypropyl methylcellulose (HPMC) in the prevention of peritoneal adhesions post-surgery is demonstrated. The physical mixture of the two carbohydrates increased the dwell time in the peritoneum while significantly improving the injectability of the polymer compared with HA alone. HA-HPMC treatment decreased the total adhesion area by ∼ 70% relative to a saline control or no treatment in a repeated cecal injury model in the rabbit. No significant cytotoxicity and minimal inflammation were associated with the blend. Furthermore, no chemical or physical processing was required prior to their use beyond simple mixing.

Local toxicity from local anesthetic polymeric microparticles

BACKGROUND

Local tissue injury from sustained-release formulations for local anesthetics can be severe. There is considerable variability in reporting of that injury. We investigated the influence of the intrinsic myotoxicity of the encapsulated local anesthetic (lidocaine, low; bupivacaine, high) on tissue reaction in rats.

METHODS

Cytotoxicity from a range of lidocaine and bupivacaine concentrations was measured in C2C12 myotubes over 6 days. Rats were given sciatic nerve blocks with 4 microparticulate formulations of lidocaine and bupivacaine: 10% (w/w) lidocaine poly(lactic-co-glycolic) acid (PLGA), 10% (w/w) bupivacaine PLGA, 50% (w/w) lidocaine PLGA, and 50% (w/w) bupivacaine PLGA. Effectiveness of nerve blockade was assessed by a modified hotplate test and weightbearing measurements. Myotoxicity was scored in histologic sections of injection sites. Bupivacaine and lidocaine release kinetics from the particles were measured.

RESULTS

Median sensory blockade duration for 50% (w/w) lidocaine was 255 (90-540) minutes versus 840 (277-1215) minutes for 50% (w/w) bupivacaine (P = 0.056). All microparticulate formulations resulted in myotoxicity. The choice of local anesthetic did not influence the severity of myotoxicity. Median myotoxicity scores for 50% (w/w) lidocaine compared with 50% (w/w) bupivacaine at 4 days were 3.4 (2.1-4.2) vs 3.3 (2.9-3.5) (P = 0.44) and at 14 days 1.9 (1.8-2.4) vs 1.7 (1.3-1.9) (P = 0.23), respectively.

CONCLUSIONS

Lidocaine and bupivacaine PLGA microspheres resulted in similar degrees of myotoxicity, irrespective of drug loading. Intrinsic myotoxicity did not predict tissue injury from sustained release of these anesthetics. Caution is warranted in the use of such devices near muscle and nerve.

Rheological blends for drug delivery. II. Prolongation of nerve blockade, biocompatibility, and in vitro-in vivo correlations

Rheological polymer blends of hyaluronic acid (HA) and hydroxypropylmethyl cellulose (HPMC) were evaluated as prolonged duration delivery vehicles for local anesthetics using a rat sciatic nerve blockade model. HA-HPMC blends extended the duration of sensory block approximately threefold compared to that achieved using a bupivacaine solution. Blending HA and HPMC facilitated the injection of higher polymer concentration delivery vehicles and reduced the rate of polymer hydration compared to HA solutions, enabling prolonged drug release. The duration of effective nerve block was correlated with each of the zero shear viscosity, polymer concentration, yield stress, and gel point frequency of the blends, while a two-parameter model correlating duration of nerve block with zero shear viscosity and humectancy provided improved fits to the in vivo data compared to any single variable alone. The blends exhibited no cytotoxicity and induced only a mild short-term inflammatory reaction in vivo at the site of injection, with all blends largely resorbed 4 days postinjection.