The importance of the molecular weight of ethyl cellulose on the properties of aqueous-based controlled release coatings

The influence of amphiphilic quaternary ammonium palmitoyl glycol chitosan (GCPQ) polymer composition on oil-loaded nanocapsule architecture

HYPOTHESIS

Predicting the exact nature of the self-assembly of amphiphilic molecules into supramolecular structures is of utmost importance for a variety of applications, but this is a challenge for nanotechnology. The amphiphilic drug delivery polymer-N-palmitoyl-N-monomethyl-N,N-dimethyl-N,N,N-trimethyl-6-O-glycolchitosan (GCPQ) self-assembles in aqueous media to form nanoparticles.

EXPERIMENT

This work aimed to develop a systematic predictive mathematical model on the eventual nature of oil-loaded GCPQ-nanoparticles and to determine the main independent variables that affect their nanoarchitecture following self-assembly. GCPQ polymers were produced with varying degree of palmitoylation (DP, 5.7-23.8 mol%), degree of quaternization (DQ, 7.2-22.7 mol%), and molecular weight (MW, 11.2-44.2 kDa) and their critical hydrophilic-lipophilic balance (cHLB) optimized to produce oil-loaded nanocapsules.

FINDINGS

Non-linear mathematical models (Particle size (nm) = 466.05 - 5.64DP - 6.52DQ + 0.13DQ2 - 0.03 MW2 - 14.48cHLB + 0.48cHLB2) were derived to predict the nanoparticle sizes (R2 = 0.998, R2adj = 0.995). Smaller nanoparticle sizes (148-157 nm) were obtained at high DP, DQ, and cHLB values, in which DP was the main independent variable responsible for nanoparticle size. Single or multiple-oil cores with small particles stabilizing polymer shells could be observed depending on the oil volume. Nanoparticle architectures, especially the nature of the oil-core(s), were driven by the DP, DQ, cHLB, and oil concentration. Here, we have developed a predictive model that may be applied to understand the nanoarchitecture of oil-loaded GCPQ-nanoparticles.

Optimization of oil-in-water emulsion capacity and stability of octenyl succinic anhydride-modified porang glucomannan (Amorphophallus muelleri Blume)

Surfactants are used to reduce surface and interfacial tension to form emulsions. Polysaccharides such as Porang Glucomannan (PG) with high viscosity can be used as surfactants. This research aimed to optimize the concentration of sodium carbonate (Na₂CO₃) and octenyl succinic anhydride (OSA) in modifying PG using a microwave. The optimization process is carried out using response surface methodology (RSM) with a two-factor central composite design (CCD), namely concentration of Na₂CO₃ (0.17–5.834%) and OSA (2.17–7.83%). The result showed that the concentration of Na₂CO₃ and OSA strongly influences emulsion capacity and stability. The optimum conditions that resulted in the highest emulsion capacity and stability were obtained at concentrations of Na₂CO₃ and OSA which were 2.25% and 6.19%, respectively. Degree of Substitution (DS), FTIR analysis, contact angle, and increased viscosity confirmed that OSA substitution occurred in PG. The characteristics of OSA-modified porang glucomannan (PGOS) such as: emulsion capacity and stability, Degree of Substitution (DS), contact angle, and viscosity increased to 34.6% and 32.5%, 1.02%, 92^o, 5720 cP, respectively. FT-IR analysis confirmed the presence of OSA substitution at 1734 cm⁻¹. PGOS can be used as a surfactant or gelator in oleogel production.

The relationship between mucoadhesive polymers and surface coating in tablets for the controlled colonic delivery of a poorly water-soluble drug

BACKGROUND

The mucoadhesive polymers play an important role in targeted and controlled drug delivery.

OBJECTIVES

This study aimed to investigate the drug release behaviour and interpret the role of mucoadhesive polymers involved in the coating layer of mucoadhesive tablets for the sustained release of a poorly water-soluble drug.

METHODS

A solid dispersion of prednisolone and zein was used in the core tablets created with two mucoadhesive polymers, which included Carbopol 940 and hydroxypropyl methylcellulose K4M. In addition, the properties of a single-layer coating, created from the combination of zein and Kollicoat MAE 100P to delay release through the upper parts of the gastrointestinal tract, were investigated in the presence of the above mucoadhesive polymers; these properties included drug dissolution, mucoadhesion, surface morphology, swelling and erosion.

RESULTS

The mucoadhesive polymer concentrations and types were integrated not only into the core tablets through a swelling/erosion mechanism but also into the surface polymer coatings for controlled drug release. HPMC was preferred in the formulations due to the ability to form pores on the surface coating, allowing water uptake so that the coating could control drug release for a later stage via a swelling/erosion mechanism.

CONCLUSION

The proposed mechanism determined in this project could be beneficial in the selection of polymers for applications targeting the colon with coated mucoadhesive tablets. Graphical abstract.

Fabrication of curcumin-zein-ethyl cellulose composite nanoparticles using antisolvent co-precipitation method

The stable colloidal nano-dispersion of curcumin (CU) loaded zein-ethyl cellulose (ZN-EC) as three hydrophobic agent in water was prepared using two step antisolvent co-precipitation method. The EC coated NPs were prepared by adding EC in ethyl acetate to the ZN-CU NPs at a concentration ratio of 1: 3.5 w/v. The prepared colloidal suspension of ZN-EC showed high physical stability during storage time. The particle diameters and zeta potential values of ZN-CU and ZN-CU-EC colloidal suspensions were 140 ± 12 nm, 38 ± 2 mV and 179 ± 12 nm, 12 ± 2 mV, respectively. Based on Scanning electron microscopy (SEM) images, participation of EC on the surface of ZN-CU particles could reduce the sticky appearance of particles. Encapsulation efficiency of CU in NPs did not improve after precipitation of EC, but the stability of NPs against pH changes, increased and release rate of CU from NPs at different pH values (3-8) were significantly reduced in comparison of ZN-CU NPs. The EC coated NPs showed the excessive protection for CU antioxidant activity during storage. In conclusion, the prepared NPs, with high physical stability, have good potential for encapsulation and delivery of CU to colon region.

An Update of Moisture Barrier Coating for Drug Delivery

Drug hydrolytic degradation, caused by atmospheric and inherent humidity, significantly reduces the therapeutic effect of pharmaceutical solid dosages. Moisture barrier film coating is one of the most appropriate and effective approaches to protect the active pharmaceutical ingredients (API) from hydrolytic degradation during the manufacturing process and storage. Coating formulation design and process control are the two most commonly used strategies to reduce water vapor permeability to achieve the moisture barrier function. The principles of formulation development include designing a coating formulation with non-hygroscopic/low water activity excipients, and formulating the film-forming polymers with the least amount of inherent moisture. The coating process involves spraying organic or aqueous coating solutions made of natural or synthetic polymers onto the surface of the dosage cores in a drum or a fluid bed coater. However, the aqueous coating process needs to be carefully controlled to prevent hydrolytic degradation of the drug due to the presence of water during the coating process. Recently, different strategies have been designed and developed to effectively decrease water vapor permeability and improve the moisture barrier function of the film. Those strategies include newly designed coating formulations containing polymers with optimized functionality of moisture barrier, and newly developed dry coating processes that eliminate the usage of organic solvent and water, and could potentially replace the current solvent and aqueous coatings. This review aims to summarize the recent advances and updates in moisture barrier coatings.

An overview of the transport of liquid molecules through structured polymer films, barriers and composites - Experiments correlated to structure-based simulations

Films engineered to control the transport of liquids are widely used through society. Examples include barriers in packaging, wound care products, and controlled release coatings in pharmaceutics. When observed at the macroscopic scale such films commonly appear homogeneous, however, a closer look reveals a complex nano- and microstructure that together with the chemical properties of the different domains control the transport properties. In this review we compare and discuss macroscopic transport properties, measured using the straightforward, yet highly powerful technique "modified Ussing chambers", also denoted side-by-side diffusion cells, for a wide range of structured polymer films and composites. We also discuss and compare the macroscopic observations and conclusions on materials properties with that of lattice Boltzmann simulations of transport properties based on underlying material structure and chemistry. The survey of the field: (i) highlights the use and power of modified Ussing Chambers for determining liquid transport properties of polymer films, (ii) demonstrates the predictability in both directions between macroscopic observations of transport using modified Ussing chambers and structure-based simulations, and (iii) provides experimental and theoretical insights regarding the transport-determining properties of structured polymer films and composites.

When drugs plasticize film coatings: Unusual formulation effects observed with metoprolol and Eudragit RS

Metoprolol tartrate and metoprolol free base loaded pellet starter cores were coated with Eudragit RS, plasticized with 25% triethyl citrate (TEC). The initial drug loading and coating level were varied from 10 to 40 and 0 to 20%, respectively. Drug release was measured in 0.1 N HCl and phosphate buffer pH 7.4. The water uptake and swelling kinetics, mechanical properties and TEC leaching of/from coated pellets and/or thin, free films of identical composition as the film coatings were monitored. The following unusual tendencies were observed: (i) the relative drug release rate from coated pellets increased with increasing initial drug content, and (ii) drug release from pellets was much faster for metoprolol free base compared to metoprolol tartrate, despite its much lower solubility (factor >70). These phenomena could be explained by plasticizing effects of the drug for the polymeric film coatings. In particular: 1) Metoprolol free base is a much more potent plasticizer for Eudragit RS than the tartrate, leading to higher film permeability and overcompensating the pronounced differences in drug solubility. Also, Raman imaging revealed that substantial amounts of the free base migrated into the film coatings, whereas this was not the case for the tartrate. 2) The plasticizing effects of the drug for the film coating overcompensated potential increasing limited solubility effects when increasing the initial drug loading from 10 to 40%. In summary, this study clearly demonstrates how important the plasticization of polymeric controlled release film coatings by drugs can be, leading to unexpected formulation effects.