Development of a prospective isopropyl alcohol-loaded pharmaceutical base using simultaneousin vitro/in vivocharacterization methods of skin performance

Bacillus licheniformis levan as a functional biopolymer in topical drug dosage forms: From basic colloidal considerations to actual pharmaceutical application

Ongoing demand in sustainable and biocompatible drug dosage forms is reflected in the search for novel pharmaceutical excipients with equal properties. A group of microbial exopolysaccharides offers a variety of biopolymers with many alleged uses and effects. This study aims to assess applicative properties of levan obtained from Bacillus licheniformis NS032, focusing on its potential co-stabilizing and drug release-controlling functions in pertaining emulsion systems. Despite its high molecular weight and partial existence in globular nanometric structures (180-190 nm), levan was successfully incorporated into both tested colloidal systems: those stabilized with synthetic/anionic or natural-origin/non-ionic emulsifiers. In the tested levan concentrations range (0.2-3.0% w/w) the monitored flow and thermal parameters failed to show linear concentration dependence, which prompted us to revisit certain colloidal fundamentals of this biopolymer. Being a part of the external phase of the investigated emulsion systems, levan contributed to formation of a matrix-like environment, offering additional stabilization of the microstructure and rheology modifying properties (hysteresis loop elevation as high as 4167±98 to 20792±3166 Pa•s^-1), especially in case of the samples where lamellar liquid crystalline formation occurred. Apart from its good water solubility and considerable conformational flexibility, the investigated homofructan easily saturated the external phase of the samples stabilized with a conventional anionic emulsifier, leading to similar properties of 0.2% and 3.0% levan-containing samples. After closer consideration of thermal and release behavior, this was considered as a favorable property for a novel excipient, offering tailored formulation characteristics even with lower levan concentrations, consequently not compromising the potential cost of the final drug dosage form.

Critical quality attributes, in vitro release and correlated in vitro skin permeation-in vivo tape stripping collective data for demonstrating therapeutic (non)equivalence of topical semisolids: A case study of "ready-to-use" vehicles

This work aimed to prove the ability of "ready-to-use" topical vehicles based on alkyl polyglucoside-mixed emulsifier (with/without co-solvent modifications) to replace the conventionally used pharmacopoeial bases (e.g., non-ionic hydrophilic cream) in compounding practice. For this purpose, considering the regulatory efforts to establish alternative, scientifically valid methods for evaluating therapeutic equivalence of topical semisolids, we performed a comparative assessment of microstructure, selected critical quality attributes (CQAs) and in vitro/in vivo product performances, by utilizing aceclofenac as a model drug. The differences in composition between investigated samples have imposed remarkable variances in monitored CQAs (particularly in the amount of aceclofenac dissolved, rheological properties and water distribution mode), reflecting the distinct differences in microstructure formed, as partially observed by polarization microscopy and confocal Raman spectral imaging. Although not fully indicative of the in vivo performances, in vitro release data (vertical diffusion vs. immersion cells) proved the microstructure peculiarities, asserting the rheological properties as decisive factor for obtained liberation profiles. Contrary, in vitro permeation results obtained using pig ear epidermis correlated well with in vivo dermatopharmacokinetic data and distinguished unequivocally between tested formulations, emphasizing the importance of skin/vehicle interactions. In summary, suggested multi-faceted approach can provide adequate proof on topical semisolids therapeutic equivalence or lack thereof.