Comparison of dissolution profiles for sustained release resinates of BCS class I drugs using USP apparatus 2 and 4: a technical note

Discriminative Dissolution Method Using the Open-Loop Configuration of the USP IV Apparatus to Compare Dissolution Profiles of Metoprolol Tartrate Immediate-Release Tablets: Use of Kinetic Parameters

The use of the USP IV apparatus (flow-through cell) has gained acceptance in recent years due to its versatility and ability to discriminate due to its hydrodynamic conditions. Therefore, the objective of the present study was to develop a discriminative dissolution method in the USP IV apparatus using the open-loop configuration, as well as to propose a method to compare non-cumulative dissolution profiles obtained in the open-loop configuration considering kinetic parameters and validate its predictive power through its comparison with independent and dependent methods using five commercial immediate-release tablet drugs (one reference drug and four generic drugs) of metoprolol tartrate as a model drug. The comparison of the non-accumulated dissolution profiles consisted of determining the geometric ratio of Cmax, AUC0∞, AUC0Cmax, and Tmax (kinetic parameters) of the generic/reference drugs, whereby generic drugs "C" and "D" presented the highest probability of similarity since their 90% confidence intervals were included, or they were very close to the acceptance interval (80.00-125.00%). These results were consistent with the f2, bootstrap f2, and dissolution efficiency approaches (independent models). In conclusion, the proposed comparison method can be an important tool to establish similarity in dissolution profiles and to facilitate the development/selection of new formulations and positively ensure bioequivalence in clinical studies.

Bio-Hybrid Hydrogels Incorporated into a System of Salicylic Acid-pH/Thermosensitive Nanocarriers Intended for Cutaneous Wound-Healing Processes

In this paper, the preparation method of bio-hybrid hydrogels incorporated into a system of salicylic acid-pH/thermosensitive nanocarriers to speed up the wound-healing process was developed. This combination creates a dual drug delivery system, which releases the model hydrophobic active substance—salicylic acid—in a gradual and controlled manner for an extended time. Our research team has determined the various properties of bio-hybrid hydrogels based on their physicochemical (swelling degree, and degradation), structural (FT-IR), morphological (SEM), and mechanical (elongation tests) traits. Moreover, empty pH/thermosensitive nanocarriers and their salicylic acid-containing systems were characterized using the following methods: DLS, TG/DTG, and DSC. Additionally, salicylic acid release profiles directly from thermosensitive nanocarriers were compared to the bio-hybrid matrix. These studies were conducted in PBS (pH = 7.4) for 7 days using the USP4 method. To evaluate the antibacterial properties of the obtained materials, the inhibition of growth of Staphylococcus aureus, Escherichia coli, Candida albicans, and Aspergillus niger—as the main microorganisms responsible for human infections—were tested. The obtained results indicated that the pH/thermosensitive nanocarrier–salicylic acid system and bio-hybrid hydrogels are characterized by antibacterial activity against both S. aureus and E. coli.

Use of Drug Release Testing to Evaluate the Retention of Abuse-Deterrent Properties of Polyethylene Oxide Matrix Tablets

Abuse-deterrent formulations (ADFs) using physical/chemical barrier approaches limit abuse by providing resistance to dosage form manipulation to limit drug extraction or altered release. Standardizing in vitro testing methods to assess the resistance to manipulation presents a number of challenges, including the variation in particle sizes resulting from the use of various tools to alter the tablet matrix (e.g., grinding, chipping, crushing). A prototype, direct-compression ADF using a sintered polyethylene oxide (PEO) matrix containing dextromethorphan, an enantiomeric form of the opioid, levorphanol, was developed to evaluate testing methodologies for retention of abuse-deterrent properties following dosage form tampering. Sintered PEO tablets were manipulated by grinding, and drug content and release were evaluated for the recovered granules. Drug content analysis revealed that higher amounts of drug were contained in the smaller size granules (< 250 μm, 190% of the theoretical amount) compared with the larger particles (> 250 μm, 55-75% of theoretical amount). Release testing was performed on various size granule fractions (> 850 μm, 500-850 μm, 250-500 μm, and < 250 μm) using USP type I (basket), type II (paddle), and type IV (flow-through) apparatus. The USP type I and type II apparatus gave highly variable release results with poor discrimination among the release rates from different size granules. The observed sticking of the hydrated granules to the baskets and paddles, agglomeration of hydrated granules within the baskets/vessels, and ongoing PEO hydration with subsequent gel formation further altered the particle size and impacted the rate of drug release. The use of a flow-through apparatus (USP type IV) resulted in improved discrimination of drug release from different size granules with less variability due to better dispersion of granules (minimal sticking and aggregation). Drug release profiles from the USP type IV apparatus showed that the larger size granules (> 500 μm) offered continued resistance to drug release following tablet manipulation, but the smaller size granules (< 500 μm) provided rapid drug release that was unhindered by the hydrated granule matrix. Since < 500-μm size particles are preferred for nasal abuse, improved direct-compression ADF formulations should minimize the formation of these smaller-sized particles following tampering to maintain the product's abuse-deterrent features.

Comparative Study of Antibacterial Effects of Titanium Dioxide Nanoparticles Alone and in Combination with Antibiotics on MDR Pseudomonas aeruginosa Strains

Introduction

The efficacy of several antimicrobial agents has been hindered due to the increasing frequency of multidrug-resistant (MDR) Pseudomonas aeruginosa strains. So, the need for new antibacterial drugs or drug combinations is urgent. Recently, desirable antibacterial effects were reported for many metals nanoparticles such as TiO₂ nanoparticles (TDNs).

Purpose

This study aims to investigate the prevalence of MDR P. aeruginosa and assess the efficiency of TDN in the treatment of MDR P. aeruginosa-associated infections.

Materials and Methods

The synthesis of TDN by the sol-gel method was carried out. Particle size measurements and morphology were done using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (HR-TEM). To investigate the physical and chemical changes of drugs due to the combination, the tested drugs, both alone and in combination with TDN, were subjected to differential scanning calorimetry (DSC), infrared (IR) spectroscopy, and X-ray diffraction studies. Antimicrobial susceptibility was detected by agar disc-diffusion assay. The minimum inhibitory concentration (MIC) of TDN and the tested antibiotics were assessed by the agar dilution method. Checkerboard analysis was performed to determine the combined effect of TDN and the tested antibiotics against 25 MDR P. aeruginosa strains.

Results

TDNs were prepared with an average particle size of 64.77 ± 0.14 nm with an accepted polydispersity index (PDI) value of 0.274 ± 0.004. TEM showed that the particles were shaped into irregular spheres. Twenty-five P. aeruginosa isolates that were absolutely resistant to cefepime (100%), highly resistant to ceftriaxone (96%), amikacin (80%), and ciprofloxacin (76%) were selected. Superior antibacterial activity of TDN was observed against the selected 25 MDR P. aeruginosa isolates. The combination of TDN and cefepime were found to show synergistic activity against all tested isolates followed by ceftriaxone (96%), amikacin (88%), and ciprofloxacin (80%).

Conclusion

Using TDN in combination with antibiotics can help in the treatment of MDR P. aeruginosa-associated infections. So, preparation of topical pharmaceutical dosage forms containing a combination of these antibiotics and TDN can be useful against MDR P. aeruginosa.

The load and release characteristics on a strong cationic ion-exchange fiber: kinetics, thermodynamics, and influences

Ion-exchange fibers were different from conventional ion-exchange resins in their non-cross-linked structure. The exchange was located on the surface of the framework, and the transport resistance reduced significantly, which might mean that the exchange is controlled by an ionic reaction instead of diffusion. Therefore, this work aimed to investigate the load and release characteristics of five model drugs with the strong cationic ion-exchange fiber ZB-1. Drugs were loaded using a batch process and released in United States Pharmacopoeia (USP) dissolution apparatus 2. Opposing exchange kinetics, suitable for the special structure of the fiber, were developed for describing the exchange process with the help of thermodynamics, which illustrated that the load was controlled by an ionic reaction. The molecular weight was the most important factor to influence the drug load and release rate. Strong alkalinity and rings in the molecular structures made the affinity between the drug and fiber strong, while logP did not cause any profound differences. The drug-fiber complexes exhibited sustained release. Different kinds and concentrations of counter ions or different amounts of drug-fiber complexes in the release medium affected the release behavior, while the pH value was independent of it. The groundwork for in-depth exploration and further application of ion-exchange fibers has been laid.

Ion-exchange resins as drug delivery carriers

There are many reports in the literature referring to the utilization of drug bound to ion-exchange resin (drug-resinate), especially in the drug delivery area. Ion-exchange resin complexes, which can be prepared from both acidic and basic drugs, have been widely studied and marketed. Salts of cationic and anionic exchange resins are insoluble complexes in which drug release results from exchange of bound drug ions by ions normally present in body fluids. Resins used are polymers that contain appropriately substituted acidic groups, such as carboxylic and sulfonic for cation exchangers; or basic groups, such as quaternary ammonium group for anion exchangers. Variables relating to the resin are the exchange capacity; degree of cross-linking, which determines the permeability of the resin, its swelling potential, and the access of the exchange sites to the drug ion; the effective pK(a) of the exchanging group, which determines the exchange affinity; and the resin particle size, which controls accessibility to the exchange ions. In this review, the properties of ion-exchange resins, selection of drugs that lend themselves to such an approach, selection of the appropriate resin, preparation of drug-resinate, evaluation of drug release, recent developments of drug-resinates, and applications are discussed.