Construction and in vitro characterization of an optimized porosity-enabled amalgamated matrix for sustained transbuccal drug delivery

Ice Templating Soft Matter: Fundamental Principles and Fabrication Approaches to Tailor Pore Structure and Morphology and Their Biomedical Applications

Porous scaffolds are widely used in biomedical applications where pore size and morphology influence a range of biological processes, including mass transfer of solutes, cellular interactions and organization, immune responses, and tissue vascularization, as well as drug delivery from biomaterials. Ice templating, one of the most widely utilized techniques for the fabrication of porous materials, allows control over pore morphology by controlling ice formation in a suspension of solutes. By fine-tuning freezing and solute parameters, ice templating can be used to incorporate pores with tunable morphological features into a wide range of materials using a simple, accessible, and scalable process. While soft matter is widely ice templated for biomedical applications and includes commercial and clinical products, the principles underpinning its ice templating are not reviewed as well as their inorganic counterparts. This review describes and critically evaluates fundamental principles, fabrication and characterization approaches, and biomedical applications of ice templating in polymer-based biomaterials. It describes the utility of porous scaffolds in biomedical applications, highlighting biological mechanisms impacted by pore features, outlines the physical and thermodynamic mechanisms underpinning ice templating, describes common fabrication setups, critically evaluates complexities of ice templating specific to polymers, and discusses future directions in this field.

In vitro, ex vivo and in silico mechanistic elucidation of the performance of an optimized porosity-controlled multi-elemental transbuccal system

PURPOSE

To elucidate the mechanisms of construction and performance of a porosity controlled, multi-elemental transbuccal system employing experimental and computational approaches.

METHODS

The production of the formulation was guided through a Box-Benkhen design employing homogenization coupled with lyophilization. The physicochemical and physicomechanical properties of the experimental design formulations were quantified with relevant analytical techniques. The influence of changes in porosity measures on the magnitude of these physical properties were explored mathematically. Furthermore, experimental outputs from the Box-Behnken design formulations were fitted into set limits and optimized using the response surface method. The optimized porosity-controlled formulation was subjected to mechanistic experimental and computational elucidations.

RESULTS

In general, the changes in magnitudes of studied porosity quantities had significant impact on formulation physicochemical and physicomechanical properties. The generation of an optimized formulation validated the stability and accuracy of the Box-Behnken experimental design. Experimental investigations revealed that the construction of this formulation is as a result of non-destructive physical interactions amongst its make-up compounds while its mechanism of performance is anchored mainly upon a gradual collapse of its ordered porous structure. Furthermore, the molecule mechanics simulations quantitatively predicted the molecular interactions inherent to multicomponent matrix formation and the mucoadhesion mechanism.

CONCLUSIONS

The fabrication and performance mechanisms of the porosity-controlled transbuccal system was successfully explored.

Oral transmucosal drug delivery--current status and future prospects

Oral transmucosal drug delivery (OTDD) dosage forms have been available since the 1980s. In contrast to the number of actives currently delivered locally to the oral cavity, the number delivered as buccal or sublingual formulations remains relatively low. This is surprising in view of the advantages associated with OTDD, compared with conventional oral drug delivery. This review examines a number of aspects related to OTDD including the anatomy of the oral cavity, models currently used to study OTDD, as well as commercially available formulations and emerging technologies. The limitations of current methodologies to study OTDD are considered as well as recent publications and new approaches which have advanced our understanding of this route of drug delivery.

The application of a crosslinked pectin-based wafer matrix for gradual buccal drug delivery

The purpose of this study was to develop crosslinked wafer matrices and establish the influence of the crosslinker type and processing sequence on achieving gradual buccal drug delivery. Three sets of drug-loaded crosslinked pectin wafers were produced employing the model water-soluble antihistamine, diphenhydramine and were compared with noncrosslinked wafers. The formulations were crosslinked with CaCl(2), BaCl(2), or ZnSO(4) pre- or postlyophilization (sets 1 and 2) as well as pre- and postlyophilization (set 3), respectively. The surface morphology, porositometry, molecular vibrational transitions, textural attributes, thermal and in vitro drug release were characterized and supported by in silico molecular mechanics simulations. Results revealed that crosslinked wafers produced smaller pore sizes (107.63 Å) compared with noncrosslinked matrices (180.53 Å) due to molecular crosslinks formed between pectin chains. Drug release performance was dependent on the wafer crosslinking production sequence. Noncrosslinked wafers displayed burst-release with 82% drug released at t(30min) compared with first-order kinetic profiles obtained for prelyophilized crosslinked matrices (50% released at t(30min) followed by steady release). Wafers crosslinked postlyophilization displayed superior control of drug release (40% at t(30min)). Molecular mechanics simulations corroborated with the experimental data and established that Ba(++), having the largest atomic radii (1.35 Å) formed a number of ionic bridges producing wafers of higher porosity (0.048 cm(2)/g) and had more influence on drug release.