Evaluating the efficacy of a group of nontraditional plasticizers on the glass transition temperature of ethyl cellulose polymer

Dibutyl sebacate as PVC ecoplasticizer-economic synthesis and functional properties

One-third of poly(vinyl chloride) (PVC) applications require plasticization to improve flexibility, softness, and processability. Phthalate esters have been widely used but are now restricted due to their toxicity. Di-n-butyl sebacate (DBS), a safe, biodegradable, and cost-effective aliphatic ester, offers superior operational properties and industrial scalability compared to phthalates. We demonstrate a scalable DBS synthesis achieving approximately 100% yield under optimized conditions (90°C, 15 mol% triethylamine-sulfuric(VI) acid catalyst, 4 : 1 BuOH to sebacic acid ratio, 2 h). Kilogram-scale DBS-plasticized PVC was produced and evaluated for key properties. The DBS-plasticized PVC showed enhanced performance, including minimal plasticizer migration (12.78% after 28 days, per EN ISO 177:2017), high extension (350%), breaking stress of 15.7 MPa, and a Shore A hardness of 80.2. These results outperform conventional phthalates, such as di-2-ethylhexyl terephthalate and di-2-ethylhexyl phthalate. The findings confirm that DBS synthesis is fully scalable and its use results in PVC materials with superior mechanical and leakage properties. This study supports the industrial adoption of DBS as an eco-friendly and effective alternative to replace toxic phthalates in PVC plasticization, promoting safer and more sustainable materials for widespread applications.

Exploring the impact of material selection on the efficacy of hot-melt extrusion

Hot-melt extrusion (HME) has emerged as a versatile and efficient technique in pharmaceutical formulation development, particularly for enhancing the solubility and bioavailability of poorly water-soluble drugs. This review delves into the fundamental principles of HME, exploring its application in drug delivery systems. A comprehensive analysis of polymers utilized in HME, such as hydroxypropyl methylcellulose, ethyl cellulose, hydroxypropyl cellulose, and polyvinylpyrrolidone, is presented, highlighting their roles in achieving controlled drug release and improved stability. The incorporation of plasticizers, such as triacetin, poly(propylene glycol), glycerol, and sorbitol, is critical in reducing the glass transition temperature (Tg) of polymer blends, thereby enhancing the processability of HME formulations. A comparison of Tg values for various polymer-plasticizer combinations is discussed using different predictive models. For researchers and industry professionals looking to optimize drug formulation strategies, this article offers valuable insights into the mechanisms through which HME enhances drug solubility and bioavailability two critical factors in oral drug delivery. Furthermore, by reviewing recent patents and marketed formulations, the article serves as a comprehensive resource for understanding both the technical advancements and commercial applications of HME. Readers will gain a deep understanding of the role of polymers and additives in HME, alongside future perspectives on how emerging materials and techniques could further revolutionize pharmaceutical development. This review is essential for those aiming to stay at the forefront of pharmaceutical extrusion technologies and their potential to improve therapeutic outcomes. The review concludes that meticulous material selection is vital for advancing pharmaceutical manufacturing processes and ensuring optimal outcomes in HME applications, thereby enhancing the overall efficacy of drug delivery systems.

The Effect of Dicarboxylic Acid Structure on the Plasticizing Ability of Its Ester

Polyvinyl chloride (PVC) belongs to the most widely used group of thermoplastics. Most of the market for PVC products belongs to plasticized compositions. Plasticizers are the most demanded additives in the polymer industry. Environmental problems and the identified toxicity of the plasticizer di(2-ethylhexyl) phthalate (DEHP) stimulate the restriction of its use and contribute to the development of alternative plasticizers. As a possible replacement for phthalates, esters of dicarboxylic acids are known to provide reduced toxicity and high frost resistance to the resulting compositions. In this regard, esters of dicarboxylic acids and ethoxylated alcohols were obtained and their compatibility with polyvinyl chloride was investigated. The plasticizing effect of the esters obtained was evaluated. The thermomechanical characteristics of PVC compositions containing the developed plasticizers were studied, the glass transition temperature was determined, and the areas of the glassy and highly elastic state of the plastics were identified. It was shown that the chemical structure of dicarboxylate used as a plasticizer determines the important technological and operational characteristics of the PVC plastics obtained. Dibutoxyethyl sebacate (DBES) has the best plasticizing effect among the synthesized esters. The expansion of the highly elastic state area for PVC samples containing this ester exceeded the industrial plasticizers DEHP and di(2-ethylhexyl) adipate (DOA). The indicators of the critical temperature of dissolution of PVC in the esters under study suggest ensuring their low migration from PVC plastics.

Thermomechanical Properties of Nontoxic Plasticizers for Polyvinyl Chloride Predicted from Molecular Dynamics Simulations

Environmental and toxicity concerns dictate replacement of di(2-ethylhexyl) phthalate (DEHP) plasticizer used to impart flexibility and thermal stability to polyvinyl chloride (PVC). Potential alternatives to DEHP in PVC include diheptyl succinate (DHS), diethyl adipate (DEA), 1,4-butanediol dibenzoate (1,4-BDB), and dibutyl sebacate (DBS). To examine whether that these bio-based plasticizers can compete with DEHP, we need to compare their tensile, mechanical, and diffusional properties. This work focuses on predicting the effect these plasticizers have on T_g, Young's modulus, shear modulus, fractional free volume, and diffusion for PVC-plasticizer systems. Where data was available, the results from this study are in good agreement with the experiment; we conclude that DBS and DHS are most promising green plasticizers for PVC, since they have properties comparable to DEHP but not the environmental and toxicity concerns.

PLGA based film forming systems for superficial fungal infections treatment

As proven in clinical trials, superficial fungal infections can be effectively treated by single topical application of terbinafine hydrochloride (Ter-HCl) in a film forming system (FFS). Poly(lactic-co-glycolic acid) (PLGA) derivatives, originally synthesized with intention to get carriers with optimized properties for drug delivery, and multifunctional plasticizers - ethyl pyruvate, methyl salicylate, or triacetin - were used for formulation of Ter-HCl loaded FFSs. After spraying, a biodegradable, transparent, adhesive, and occlusive thin layer is formed on the skin, representing drug depot. In situ formed films were characterized by thermal, structural, viscoelastic, and antifungal properties as well as drug release and skin penetration. DSC and SEM showed fully amorphous films with Ter-HCl dissolved in PLGA in high concentration (up to 15%). FFSs are viscoelastic fluids with viscosity which can be easily adjusted by the type of plasticizer used and its concentration. The formulations showed excellent bioadhesion properties, thus ensuring persistence on the skin. In situ film based on branched PLGA/A plasticized with 10% of ethyl pyruvate allowed prolonged release of Ter-HCl by linear kinetics for the first 6 days with a total time of almost 14 days. During ex vivo human skin penetration experiment, Ter-HCl was found to be located only in its target layer, the epidermis. According to our results, plasticized branched PLGA derivatives loaded by Ter-HCl are suitable for the development of FFSs for superficial fungal infections treatment.

Controlled Release Film Forming Systems in Drug Delivery: The Potential for Efficient Drug Delivery

Despite many available approaches for transdermal drug delivery, patient compliance and drug targeting at the desired concentration are still concerns for effective therapies. Precise and efficient film-forming systems provide great potential for controlling drug delivery through the skin with the combined advantages of films and hydrogels. The associated disadvantages of both systems (films and hydrogels) will be overcome in film-forming systems. Different strategies have been designed to control drug release through the skin, including changes to film-forming polymers, plasticizers, additives or even model drugs in formulations. In the current review, we aim to discuss the recent advances in film-forming systems to provide the principles and review the methods of these systems as applied to controlled drug release. Advances in the design of film-forming systems open a new generation of these systems.

Biophysical elucidation of the mechanism of enhanced drug release and topical delivery from polymeric film-forming systems

The effect of incorporating the lipidic medium-chain triglyceride (MCT) into polymeric film-forming systems (FFS) for topical drug delivery has been evaluated. First, the in vitro release of betamethasone-17-valerate (BMV), a representative dermatological drug, was determined from FFS comprising either hydrophobic polyacrylate co-polymers, or hydrophilic hydroxypropyl cellulose, with and without MCT. Release was enhanced from both polymers in the presence of MCT. Atomic force microscopy imaging and nanoindentation of FFS with MCT revealed two-phase structured films with softer inclusions (0.5 to 4μm in diameter) surrounded by a more rigid structure. Chemical mapping with Raman micro-spectroscopy showed that MCT was primarily confined to the inclusions within the polymer, which predominated in the surrounding film. BMV was distributed throughout the film but was more concentrated outside the inclusions. Furthermore, while BMV dissolved better into the hydrophobic films, it was more soluble in the MCT inclusions in hydrophilic films, suggesting its increased availability for diffusion from these softer regions of the polymer and explaining the release enhancement observed. Second, ex vivo skin penetration studies clearly revealed that uptake of BMV was higher from hydrophobic FFS than that from the more hydrophilic polymer due, at least in part, to the superior anti-nucleation efficiency of the former. Drug was quickly taken up into the SC from which it then diffused continuously over a sustained period into the lower, viable skin layers. In the presence of MCT, the overall uptake of BMV was increased and provides the basis for further optimisation of FFS as simple, convenient and sustained formulations for topical therapy.