Partially hydrolyzed polyvinyl alcohol for fusion-based pharmaceutical formulation processes: Evaluation of suitable plasticizers

Self-crosslinked polyvinyl alcohol/cellulose nanofibril cryogels loaded with synthesized aminophosphonates as antimicrobial wound dressings

Microbial infection is the most common obstacle in the wound healing process, leading to wound healing impairment and complications and ultimately increasing morbidity and mortality. Due to the rising number of pathogens evolving resistance to the existing antibiotics used for wound care, alternative approaches are urgently required. In this study, α-aminophosphonate derivatives as antimicrobial agents were synthesized and incorporated into self-crosslinked tri-component cryogels composed of fully hydrolyzed polyvinyl alcohol (PVA-F), partially hydrolyzed polyvinyl alcohol (PVA-P), and cellulose nanofibrils (CNFs). Initially, the antimicrobial activity of four α-aminophosphonate derivatives against selected skin bacterial species was tested and their minimum inhibitory concentration was determined based on which the most effective compound was loaded into the cryogels. Next, the physical and mechanical properties of cryogels with various blending ratios of PVA-P/PVA-F and fixed amounts of CNFs were assessed, and drug release profiles and biological activities of drug-loaded cryogels were analyzed. Assessment of α-aminophosphonate derivatives showed the highest efficacy of a cinnamaldehyde-based derivative (Cinnam) against both Gram-negative and Gram-positive bacteria compared to other derivatives. The physical and mechanical properties of cryogels showed that PVA-P/PVA-F with a 50/50 blending ratio had the highest swelling ratio (1600%), surface area (523 m² g^-1), and compression recoverability (72%) compared to that with other blending ratios. Finally, antimicrobial and biofilm development studies showed that the cryogel loaded with a Cinnam amount of 2 mg (relative to polymer weight) showed the most sustained drug release profile over 75 h and had the highest efficacy against Gram-negative and Gram-positive bacteria. In conclusion, self-crosslinked tri-component cryogels loaded with the synthesized α-aminophosphonate derivative, having both antimicrobial and anti-biofilm formation properties, can have a significant impact on the management of uprising wound infection.

3D printing of pharmaceutical oral solid dosage forms by fused deposition: the enhancement of printability using plasticised HPMCAS

3D printing (3DP) by fused deposition modelling (FDM) is one of the most extensively developed methods in additive manufacturing. Optimizing printability by improving feedability, nozzle extrusion, and layer deposition is crucial for manufacturing solid oral dosage forms with desirable properties. This work aimed to use HPMCAS (Affinisol^TM HPMCAS 716) to prepare filaments for FDM-3DP using hot-melt extrusion (HME). It explored and demonstrated the effect of HME-filament composition and fabrication on printability by evaluating thermal, mechanical, and thermo-rheological properties. It also showed that the HME-Polymer filament composition used in FDM-3DP manufacture of oral solid dosage forms provides a tailored drug release profile. HME (HAAKE MiniLab) and FDM-3DP (MakerBot) were used to prepare HME-filaments and printed objects, respectively. Two diverse ways of improving the mechanical properties of HME-filaments were deduced by changing the formulation to enable feeding through the roller gears of the printer nozzle. These include plasticizing the polymer and adding an insoluble structuring agent (talc) into the formulation. Experimental feedability was predicted using texture analysis results was a function of PEG concentration, and glass-transition temperature (T_g) values of HME-filaments. The effect of high HME screw speed (100 rpm) resulted in inhomogeneity of HME-filament, which resulted in inconsistency of the printer nozzle extrudate and printed layers. The variability of the glass-transition temperature (T_g) of the HME-filament supported by scanning electron microscopy (SEM) images of nozzle extrudates and the lateral wall of the printed tablet helped explain this result. The melt viscosity of HPMCAS formulations was investigated using a capillary rheometer. The high viscosity of unplasticized HPMCAS was concluded to be an additional restriction for nozzle extrusion. The plasticization of HPMCAS and the addition of talc into the formulation were shown to improve thickness consistency of printed layers (using homogeneous HME-filaments). A good correlation (R²=0.9546) between the solidification threshold (low-frequency oscillation test determined by parallel-plate rheometer) and T_g of HME-filaments was also established. Drug-loaded and placebo HPMCAS-based formulations were shown to be successfully printed, with the former providing tailored drug release profiles based on variation of internal geometry (infill).

Drug Amorphous Solid Dispersions Based on Poly(vinyl Alcohol): Evaluating the Effect of Poly(propylene Succinate) as Plasticizer

Although significant actions have been taken towards the utilization of poly(vinyl alcohol) (PVA) in the preparation of drug amorphous solid dispersions (ASDs) using fusion-based techniques (such as melt-quench cooling and hot-melt extrusion), several drawbacks regarding its rather high melting temperature and its thermal degradation profile make the use of the polymer extremely challenging. This is especially important when the active pharmaceutical ingredient (API) has a lower melting temperature (than PVA) or when it is thermally labile. In this vein, a previous study showed that newly synthesized polyester-based plasticizers may improve the processability and the thermal properties of PVA. However, the effects of such polyester-based plasticizers on the drug’s physicochemical and pharmaco-technical properties are yet unknown. Hence, the aim of the present study is to extend our previous findings and evaluate the use of poly(propylene succinate) (PPSu, i.e., the most promising plasticizer in regard to PVA) in the preparation of drug-loaded PVA-based ASDs. Dronedarone (DRN), a poorly water-soluble API, was selected as a model drug, and drug ASDs (using either neat PVA or PVA-PPSu) were prepared using the melt-mixing/quench cooling approach at low melting temperatures (i.e., 170 °C). DSC and pXRD analysis showed that a portion of the API remained crystalline in the ASDs prepared only with the use of neat PVA, while the samples having PPSu as a plasticizer were completely amorphous. Further evaluation with ATR-FTIR spectroscopy revealed the formation of significant intermolecular interactions between the API and the PVA-PPSu matrix, which could explain the system’s physical stability during storage. Finally, dissolution studies, conducted under nonsink conditions, revealed that the use of PVA-PPSu is able to maintain DRN’s sustained supersaturation for up to 8 h.

Chloramphenicol Loaded Sponges Based on PVA/Nanocellulose Nanocomposites for Topical Wound Delivery

In the present study, polymer sponges based on poly(vinyl alcohol) (PVA) were prepared for the topical wound administration of chloramphenicol (CHL), an antibiotic widely used to treat bacterial infections. Nanocellulose fibrils (CNF) were homogenously dispersed in PVA sponges in three different ratios (2.5, 5, and 10 wt %) to improve the mechanical properties of neat PVA sponges. Infrared spectroscopy showed hydrogen bond formation between CNF and PVA, while scanning electron microscopy photos verified the successful dispersion of CNF to PVA sponges. The addition of CNF successfully enhanced the mechanical properties of PVA sponges, exhibiting higher compressive strength as the content of CNF increased. The PVA sponge containing 10 wt % CNF, due to its higher compression strength, was further studied as a matrix for CHL delivery in 10, 20, and 30 wt % concentration of the drug. X-ray diffraction showed that CHL was encapsulated in an amorphous state in the 10 and 20 wt % samples, while some crystallinity was observed in the 30 wt % ratio. In vitro dissolution studies showed enhanced CHL solubility after its incorporation in PVA/10 wt % CNF sponges. Release profiles showed a controlled release lasting three days for the sample containing 10 wt % CHL and 1.5 days for the other two samples. According to modelling, the release is driven by a pseudo-Fickian diffusion.

Study of the effect of the addition of plasticizers on the physical properties of biodegradable films based on kefiran for potential application as food packaging

Spectroscopies analysis indicated that kefiran contains branched hexasaccharide repeating units. Neat kefiran films, 2 and 5% w/w of glycerol, d-glucitol, d-galactitol, d-mannitol, and d-limonene were incorporated as plasticizers. Neat and plasticized kefiran films were characterized by physical, thermal, mechanical, optical, and water solubilization properties. Neat kefiran had a glass transition temperature (T_g) of -20 ± 2 °C and, with the addition of plasticizers between -15 to -17 ± 2 °C. The values were close to the neat kefiran, and the results could be attributed to a lower amount of plasticizer used. The solubility of the glycerol plasticized films increases by 33% and decreased with the concentration of other plasticizers in comparison with the neat kefiran. d-glucitol and d-galactitol decreased the microhardness and Young's Modulus of films around 30% and 74% respectively, obtaining more flexible kefiran films. Kefiran based films could find applications as potential materials in the food-packaging industry.

Low Molecular Weight Oligomers of Poly(alkylene succinate) Polyesters as Plasticizers in Poly(vinyl alcohol) Based Pharmaceutical Applications

The plasticizing effect of three low molecular weight oligomers of aliphatic poly(alkylene succinate) polyesters, namely poly(butylene succinate) (PBSu), poly(ethylene succinate) (PESu), and poly(propylene succinate) (PPSu), on partially hydrolyzed poly(vinyl alcohol) (PVA) used in melt-based pharmaceutical applications, was evaluated for the first time. Initially, the three aliphatic polyesters were prepared by the melt polycondensation process and characterized by differential scanning calorimetry (DSC), ¹H NMR, intrinsic viscosity, and size exclusion chromatography (SEC). Subsequently, their effect on the thermophysical and physicochemical properties of PVA was thoroughly evaluated. According to the obtained results, PVA was completely miscible with all three polyesters, while PESu induced PVA’s thermal degradation, with the phenomenon starting from ~220 °C, in contrast to PBSu and PPSu, where a thermal profile similar to PVA was observed. Furthermore, molecular interactions between PVA and the prepared poly(alkylene succinate) polyesters were revealed by DSC, ATR-FTIR, and molecular dynamics simulations. Finally, melt flow index (MFI) measurements showed that, in contrast to PBSu, the use of PESu or PPSu significantly improved PVA’s melt flow properties. Hence, according to findings of the present work, only the use of low molecular weight PPSu is suitable in order to reduce processing temperature of PVA and improve its melt flow properties (plasticizing ability) without affecting its thermal decomposition.