Design of an interpolyelectrolyte gastroretentive matrix for the site-specific zero-order delivery of levodopa in Parkinson's disease

Characteristics of Interpolyelectrolyte Complexes Based on Different Types of Pectin with Eudragit® EPO as Novel Carriers for Colon-Specific Drug Delivery

Given that pectin is a well-known substance used for drug delivery, we aimed to obtain and further examine the efficacy of interpolyelectrolyte complexes based on citrus or apple pectin and the Eudragit® EPO for using these carriers in oral drug delivery. To characterize the physicochemical properties of these compounds, turbidity, gravimetry, viscosity, elementary analysis, FTIR spectroscopy, and DSC analysis were utilized. Diffusion transport characteristics were evaluated to assess the swelling ability of the matrices and the release of diclofenac sodium. To examine the release parameters, mathematical modeling was performed by using the Korsmayer-Peppas and Logistic equations as well. During the turbidity study, stoichiometry compositions were selected for the developed IPECs EPO/PecA and EPO/PecC at pH values = 4.0, 5.0, 6.0, and 7.0. The FTIR spectra of the complexes were characterized by an increase in the intensity of the bands at 1610 cm-1 and 1400 cm-1. According to the DSC analysis, IPEC has a certain Tg = 57.3 °C. The highest release rates were obtained for IPEC EPO/PecC_1 and EPO/PecC_4. The mechanism of drug transport from the matrices IPEC EPO/PecC, IPEC EPO/PecA_3, and EPO/PecA_4 can be characterized as Super Case II. Anomalous release (non-Fickian release) is typical for IPEC EPO/PecA_1 and EPO/PecA_2. Thus, the resulting systems can be further used for the effective delivery of the drugs to the colon.

Characterization of an In Vitro/Ex Vivo Mucoadhesiveness Measurement Method of PVA Films

Transmucosal drug delivery systems can be an attractive alternative to conventional oral dosage forms such as tablets. There are numerous in vitro methods to estimate the behavior of mucoadhesive dosage forms in vivo. In this work, a tensile test system was used to measure the mucoadhesion of polyvinyl alcohol films. An in vitro screening of potential influencing variables was performed on biomimetic agar/mucin gels. Among the test device-specific factors, contact time and withdrawal speed were identified as influencing parameters. In addition, influencing factors such as the sample area, which showed a linear relationship in relation to the resulting work, and the liquid addition, which led to an abrupt decrease in adhesion, could be identified. The influence of tissue preparation was investigated in ex vivo experiments on porcine small intestinal tissue. It was found that lower values of F_max and W_ad were obtained on processed and fresh tissue than on processed and thawed tissue. Film adhesion on fresh, unprocessed tissue was lowest in most of the animals tested. Comparison of ex vivo measurements on porcine small intestinal tissue with in vitro measurements on agar/mucin gels illustrates the inter- and intra-individual variability of biological tissue.

Pharmaceutical and pharmacokinetic evaluation of a newly formulated multiparticulate matrix of levodopa and carbidopa

Levodopa is routinely co-administered with carbidopa in the management of Parkinson's disease. Although the aforementioned combination therapy is effective, there may be fluctuating plasma levels of levodopa after oral administration. We formulated and evaluated the kinetic characteristics of the chitosan-pectin-based multiparticulate matrix of levodopa and carbidopa. Pectin was extracted from the cocoa husk, and the chitosan-pectin-based matrix was prepared by wet granulation. Formulations were evaluated for drug-excipient compatibility, drug content, precompression properties and in vitro release. For pharmacokinetic evaluation, rats were put into groups and administered either chitosan-pectin based matrix of levodopa/carbidopa, Sinemet^® CR or levodopa/carbidopa immediate release powder. Rats were administered the different formulations of levodopa/carbidopa (20/5 mg/kg) per os every 12 hours. The pharmacokinetic parameters of levodopa were estimated for the various treatment groups. The percentage content of levodopa and carbidopa in the various formulations was within the acceptance criteria. The AUC_0-24 for levodopa/carbidopa multiparticulate matrix (Formulation 3: 484.98 ± 18.70 μg.hr/mL); Formulation 4: 535.60 ± 33.04 μg.hr/mL), and C_max (Formulation 3: 36.28 ± 1.52 μg/mL; Formulation 4: 34.80 ± 2.19 μg/mL) were higher than Sinemet^® CR (AUC_0-24 262.84 ± 16.73 μg.hr/mL and C_max 30.62 ± 3.37 μg/mL). The t _1/2 of the new formulation was longer compared to Sinemet^® CR.

Recent advances in pain management based on nanoparticle technologies

BACKGROUND

Pain is a vital sense that indicates the risk of injury at a particular body part. Successful control of pain is the principal aspect in medical treatment. In recent years, the advances of nanotechnology in pain management have been remarkable. In this review, we focus on literature and published data that reveal various applications of nanotechnology in acute and chronic pain management.

METHODS

The presented content is based on information collected through pain management publications (227 articles up to April 2021) provided by Web of Science, PubMed, Scopus and Google Scholar services.

RESULTS

A comprehensive study of the articles revealed that nanotechnology-based drug delivery has provided acceptable results in pain control, limiting the side effects and increasing the efficacy of analgesic drugs. Besides the ability of nanotechnology to deliver drugs, sophisticated nanosystems have been designed to enhance imaging and diagnostics, which help in rapid diagnosis of diseases and have a significant impact on controlling pain. Furthermore, with the development of various tools, nanotechnology can accurately measure pain and use these measurements to display the efficiency of different interventions.

CONCLUSIONS

Nanotechnology has started a new era in the pain management and many promising results have been achieved in this regard. Nevertheless, there is still no substantial and adequate act of nanotechnology in this field. Therefore, efforts should be directed to broad investigations.

Emerging technologies to increase gastrointestinal transit times of drug delivery systems

Apart from already established technologies to increase gastrointestinal transit times, including devices rapidly increasing in size once they have reached the stomach in order to retard the passage through the pylorus, formulations that float on gastric fluids and mucoadhesive drug delivery systems adhering to the gastrointestinal mucosa, there are new technologies emerging that might be game changing. They include mucus permeating nanocarriers that are able to diffuse deeply into the mucus gel layer of the gastric and intestinal mucosa remaining there for a prolonged time period (i), charge-converting nanocarriers that shift their zeta potential from negative to positive within the mucus gel layer providing strong ionic bonds with anionic mucus glycoproteins (ii) and thiolated nanocarriers and cyclodextrins form even covalent bonds with cysteine-rich subdomains of mucus glycoproteins (iii). Within this review we will provide an overview about these emerging new technologies and will critically discuss their potential and shortcomings.

Modeling, design and manufacture of innovative floating gastroretentive drug delivery systems based on hot-melt extruded tubes

The problem of many gastroretentive systems is the mechanistic connection of drug release and gastric retention control. This connection could be successfully separated by formulating hollow tubes via hot-melt extrusion and sealing both tube ends, which led to immediately floating devices. The tube wall consisted of metformin crystals embedded in an inert polymer matrix of Eudragit® RS PO and E PO. Very high drug loadings of up to 80% (w/w) were used without generating a 'burst release'. Sustained release profiles from four to more than twelve hours were achieved by varying the polymer proportions without affecting the floatability. Buoyancy was found to mainly depend on the cylinder design, i.e. the outer to inner diameter ratio. This allowed the polymer/metformin composition to be changed without affecting buoyancy, i.e. a separation of floatability and release control was achieved. A prediction model was implemented that allowed for the buoyancy force to be determined with high accuracy by selecting a suitable ratio of outer to inner diameter of the modular tube die. Wall thickness and mass normalized surface area were identified as geometric parameters that mainly influenced the release properties. Conclusively, this study offers a highly flexible and rational manufacturing approach for the development of gastroretentive floating drug delivery systems.

Chitosan-Based Mucoadhesive Vaginal Tablets for Controlled Release of the Anti-HIV Drug Tenofovir

Vaginal microbicides have the potential to give women at high risk of contracting HIV the option of self-protection by preventing the sexual transmission of the virus. In this paper, mucoadhesive vaginal tablets based on chitosan, alone and in combination with pectin and locust bean gum, were developed for the sustained release of tenofovir (an antiretroviral drug). The formulations were placed in simulant vaginal fluid (SVF) to swell, and Hg porosity and SEM microscopy were used for the microstructural characterization of the swelling witnesses. The results show that the association of pectin and chitosan generated polyelectrolyte complexes and produced a robust system able to maintain its structure during the swelling process, when small pores are formed. Drug release and bovine vaginal mucoadhesion studies were performed in SVF showing that tenofovir-controlled dissolution profiles and adhesion to the mucosa were conditioned by the swelling processes of the polymer/s in each formulation. Tablets based on chitosan/pectin have the most homogeneous tenofovir dissolution profiles and last up to 96 h, remaining attached to the vaginal mucosa for the same period. These formulations can therefore be considered a good option for the self-protection of women from the sexual transmission of HIV.

In silico analytico-mathematical interpretation of biopolymeric assemblies: Quantification of energy surfaces and molecular attributes via atomistic simulations

Static-lattice atomistic simulations, in vacuum and solvent phase, have been recently employed to quantify the "in vitro-in vivo-in silico" performance-correlation profile of various drug delivery systems and biomaterial scaffolds. The reactional profile of biopolymers was elucidated by exploring the spatial disposition of the molecular components with respect to the formulation conditions and the final release medium. This manuscript provides a brief overview of recently completed and published studies related to molecular tectonics of: (a) the nanoformation and solvation properties of the surfactant-emulsified polymeric systems; (b) the formation and chemistry of polyelectrolyte complexes; (c) the effect of a plasticizer and/or drug on the physicomechanical properties of biomedical archetypes; (d) the molecular modeling templates to predict stimuli- and environmentally esponsive systems; and (e) the polymer-mucopeptide complexes and intermacromolecular networks. Furthermore, this report provides a detailed account of the role of molecular mechanics energy relationships toward the interpretation and understanding of the mechanisms that control the formation, fabrication, selection, design, performance, complexation, interaction, stereospecificity, and preference of various biopolymeric systems for biomedical applications.

Improved oral bioavailability and therapeutic efficacy of erlotinib through molecular complexation with phospholipid

The current study was aimed to prepare a molecular complex of erlotinib (ERL) with phospholipid (PC) for enhancement of solubility and thus bioavailability, therapeutic efficacy and reducing the toxicity of erlotinib. Phospholipid complex of drug was prepared by solvent evaporation method and characterized by differential scanning calorimetry (DSC), Fourier transform infra-red spectroscopy (FT-IR), proton and phosphorus nuclear magnetic resonance spectroscopy (1H NMR and 31P NMR), powder X-ray diffraction (P-XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), which all explained the interactions of two components, validating the complexation phenomenon. In silico study also supported the phase change and molecular interactions for the establishment of ERL-PC. Spherical shaped nanostructures with 183.37±28.61nm size, -19.52±6.94mV potential and 28.59±2.66% loading efficiency were formed following dispersion of ERL-PC in aqueous media. In vitro release study revealed the higher release of ERL-PC due to amorphization and solubilization of drug. Caco-2 cell uptake resulted in ∼2 fold higher uptake of ERL-PC than free drug. In vitro cell culture studies were performed using human pancreatic adenocarcinoma cell lines, which demonstrated the higher cytotoxicity and apoptosis in case of ERL-PC. In vivo pharmacokinetics also supported the in vitro observations and showed ∼1.7 fold higher bioavailability with ERL-PC than ERL. Finally, in vivo efficacy and toxicity studies explained the superiority of ERL-PC over the free drug. Based on the results, phospholipid complex appears to be a promising tool to enhance bioavailability, efficacy, cytotoxicity and safety of erlotinib.

Ex Vivo and In Vivo Characterization of Interpolymeric Blend/Nanoenabled Gastroretentive Levodopa Delivery Systems

One approach for delivery of narrow absorption window drugs is to formulate gastroretentive drug delivery systems. This study was undertaken to provide insight into in vivo performances of two gastroretentive systems (PXLNET and IPB matrices) in comparison to Madopar® HBS capsules. The pig model was used to assess gastric residence time and pharmacokinetic parameters using blood, cerebrospinal fluid (CSF), and urine samples. Histopathology and cytotoxicity testing were also undertaken. The pharmacokinetic parameters indicated that levodopa was liberated from the drug delivery systems, absorbed, widely distributed, metabolized, and excreted. C_max were 372.37, 257.02, and 461.28 ng/mL and MRT were 15.36, 14.98, and 13.30 for Madopar HBS capsules, PXLNET, and IPB, respectively. In addition, X-ray imaging indicated that the gastroretentive systems have the potential to reside in the stomach for 7 hours. There was strong in vitro-in vivo correlation for all formulations with r² values of 0.906, 0.935, and 0.945 for Madopar HBS capsules, PXLNET, and IPB, respectively. Consequently, PXLNET and IPB matrices have pertinent potential as gastroretentive systems for narrow absorption window drugs (e.g., L-dopa) and, in this application specifically, enhanced the central nervous system and/or systemic bioavailability of such drugs.

Overview on gastroretentive drug delivery systems for improving drug bioavailability

In recent decades, many efforts have been made in order to improve drug bioavailability after oral administration. Gastroretentive drug delivery systems are a good example; they emerged to enhance the bioavailability and effectiveness of drugs with a narrow absorption window in the upper gastrointestinal tract and/or to promote local activity in the stomach and duodenum. Several strategies are used to increase the gastric residence time, namely bioadhesive or mucoadhesive systems, expandable systems, high-density systems, floating systems, superporous hydrogels and magnetic systems. The present review highlights some of the drugs that can benefit from gastroretentive strategies, such as the factors that influence gastric retention time and the mechanism of action of gastroretentive systems, as well as their classification into single and multiple unit systems.

A Co-blended Locust Bean Gum and Polymethacrylate-NaCMC Matrix to Achieve Zero-Order Release via Hydro-Erosive Modulation

Locust bean gum (LBG) was blended with a cellulose/methacrylate-based interpolyelectrolyte complex (IPEC) to assess the hydro-erosive influence of addition of a polysaccharide on the disposition and drug delivery properties inherent to IPEC matrix. The addition of LBG modulated the drug (levodopa) release characteristics of the IPEC by reducing excessive swelling and preventing bulk erosion. After 8 h in pH 4.5 dissolution medium, gravimetric analysis established that IPEC tablet matrix eroded by 30% of the initial weight due to bulk erosion while LBG-blended IPEC (LBG-b-IPEC) demonstrated surface erosion accounting to 62% of initial weight (596→226.8 mg). Mathematical modeling of the drug release data depicted a transformation from non-Fickian mechanism (IPEC matrices) to zero-order drug release pattern (LBG-b-IPEC matrices) with the linearity of release profile being close to 1 (R (2) = 0.99). Physicochemical characterizations employing Fourier transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) explicated that LBG interacted with IPEC by its hydrophilic groups associating with the existing water-holding bodies of IPEC to produce compact matrices. The lattice atomistic modeling elucidated that LBG acted as a linker with the formation of intra- and intermolecular hydrogen bonds generating a highly stabilized polysaccharide-polyelectrolytic structure which influenced the improved properties observed.