Drug loading and release properties of ion-exchange resin complexes as a drug delivery matrix

Polystyrene Sulfonate Resin as an Ophthalmic Carrier for Enhanced Bioavailability of Ligustrazine Phosphate Controlled Release System

Topical ocular sustained-release drug delivery systems represent an effective strategy for the treatment of ocular diseases, for which a suitable carrier has yet to be sufficiently developed. Herein, an eye-compatible sodium polystyrene sulfonate resin (SPSR) was synthesized with a uniform particle size of about 3 μm. Ligustrazine phosphate (LP) was adsorbed to SPSR by cation exchange to form LP@SPSR. LP@SPSR suspension eye drops were further developed using the combination of Carbopol 934P and xanthan gum as suspending agents. The LP@SPSR suspension showed a sustained release in vitro, which was consistent with the observed porcine corneal penetration ex vivo. Pharmacokinetics in tear fluid of rabits indicated that LP@SPSR suspension led to prolonged ocular retention of LP and a 2-fold improved the area under the drug concentration-time curve (AUC0-t). Pharmacokinetics in the aqueous humor of rabbits showed 2.8-fold enhancement in the AUC0-t compared to LP solution. The LP@SPSR suspension exhibited no cytotoxicity to human corneal epithelial cells, nor irritation was observed in rabbit eyes. Thus, the LP@SPSR suspension has been validated as a safe and sustained release system leading to enhanced ophthalmic bioavailability for treating ocular diseases.

Formulation development, in vivo bioequivalence and pediatric PBPK modeling studies of taste-masked ciprofloxacin chewable tablets

A taste-masked chewable tablet of ciprofloxacin using ion exchange resin Kyron T-134 for enhancing compliance for the paediatric population was developed. The drug-to-resin ratio was optimized for maximum taste masking by studying the effects of soaking time (X1) and mixing time (X2) on complexation (%) using Central Composite Rotatable Design (CCRD). The resin complexes were characterized by bitterness score, DSC, FTIR, and PXRD. The complex was further formulated and optimized into chewable tablets through full factorial design, The optimized formulation was subjected to a bioequivalence study, and a virtual approach of PBPK modelling was adapted to predict the pharmacokinetics of the drug in the paediatric group. The drug resin ratio of 1:1.5 yielded an optimum drug loading of 99.05%. The optimized formulation shows minimum disintegration time with more than 99% drug release within 30 min. The formulation F-9 was found to be bioequivalent with a geometric mean ratio of Cmax, Tmax, AUC0-t, and AUC0-∞ within 90% CI. It was concluded that quality by design approach can successfully be applied to optimize the drug resin ratio and PBPK modeling is a successful predictive tool for estimating the pharmacokinetics of ciprofloxacin HCl in the paediatric population.

Templated Reactive Crystallization of Active Pharmaceutical Ingredient in Hydrogel Microparticles Enabling Robust Drug Product Processing

Commercialization of most promising active pharmaceutical ingredients (APIs) is impeded either by poor bioavailability or challenging physical properties leading to costly manufacture. Bioavailability of ionizable hydrophobic APIs can be enhanced by its conversion to salt form. While salt form of the API presents higher solution concentration than the non-ionized form, poor physical properties resulting from particle anisotropy or non-ideal morphology (needles) and particle size distribution not meeting dissolution rate targets can still inhibit its commercial translation. In this regard, API physical properties can be improved through addition of non-active components (excipients or carriers) during API manufacture. In this work, a facile method to perform reactive crystallization of an API salt in presence of the microporous environment of a hydrogel microparticle is presented. Specifically, the reaction between acidic antiretroviral API, raltegravir and base potassium hydroxide is performed in the presence of polyethylene glycol diacrylamide hydrogel microparticles. In this bottom-up approach, the spherical template hydrogel microparticles for the reaction lead to monodisperse composites loaded with inherently micronized raltegravir-potassium crystals, thus improving API physical properties without hampering bioavailability. Overall, this technique provides a novel approach to reactive crystallization while maintaining the API polymorph and crystallinity.

In Situ Forming Chitosan-Alginate Interpolymer Complex Bioplatform for Wound Healing and Regeneration

Cytocompatibility, biocompatibility, and biodegradability are amongst the most desirable qualities of wound dressings and can be tuned during the bioplatform fabrication steps to enhance wound healing capabilities. A three-stepped approach (partial-crosslinking, freeze-drying, and pulverisation) was employed in fabricating a particulate, partially crosslinked (PC), and transferulic acid (TFA)-loaded chitosan-alginate (CS-Alg) interpolymer complex (IPC) with enhanced wound healing capabilities. The PC TFA-CS-Alg IPC bioplatform displayed fluid uptake of 3102% in 24 h and a stepwise degradation up to 53.5% in 14 days. The PC TFA-CS-Alg bioplatform was used as a bioactive delivery system with an encapsulation efficiency of 65.6%, bioactive loading of 9.4%, burst release of 58.27%, and a steady release of 1.91% per day. PC TFA-CS-Alg displayed a shift in cytocompatibility from slightly cytotoxic (60-90% cell viability) to nontoxic (> 90% cell viability) over a 72-h period in NIH-3T3 cells. The wound closure and histological evaluations of the lesions indicated better wound healing performance in lesions treated with PC TFA-CS-Alg and PC CS-Alg compared to those treated with the commercial product and the control. Application of the particulate bioplatform on the wound via sprinkles, the in situ hydrogel formation under fluid exposure, and the accelerated wound healing performances of the bioplatforms make it a good candidate for bioactive delivery system and skin tissue regeneration.

Investigation of Chloroquine Resinate Feasibility and In Vitro Taste Masking Evaluation for Pediatric Formulations

In this study, chloroquine resinates were prepared at a 1:1 (w:w) drug-to-resin ratio using the batch method with polacrilex (PC), sodium polystyrene sulfonate (SPS), and polacrilin potassium (PP) ion exchange resins (IER). The influence of drug/resin ratio and pH of the medium on drug loading efficiency was explored. UV-VIS spectrophotometric analysis showed that SPS resin had high loading efficiency for chloroquine diphosphate (CLP), above 89%, regardless of the pH. PP resin was more effective at pH 5.0 (90.68%) than at pH 1.0 (2.09%), and PC resin had only 27.63% of CLP loading efficiency. CLP complexation with IER yielded amorphous mixtures according to results from differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD), thus indicating drug-resin interaction. The taste masking efficiency was evaluated with in vitro methods using an adapted dissolution test and an electronic tongue system. During dissolution tests, SPS released only 1.0% of CLP after 300 s, while PP released over 10% after 90 s in simulated saliva solution. The electronic tongue distinguished the samples containing CLP, resins, and resinates by using multidimensional projection techniques that indicated an effective drug taste masking. In an accelerated stability study, the drug contents did not decrease in chloroquine resinates, and there was no physical degradation of the resinates after 60 days. Using chloroquine resinates therefore represents a novel way to evaluate taste masking in vitro which is relevant for the early formulation development process.

Towards principled design of cancer nanomedicine to accelerate clinical translation

Nanotechnology in medical applications, especially in oncology as drug delivery systems, has recently shown promising results. However, although these advances have been promising in the pre-clinical stages, the clinical translation of this technology is challenging. To create drug delivery systems with increased treatment efficacy for clinical translation, the physicochemical characteristics of nanoparticles such as size, shape, elasticity (flexibility/rigidity), surface chemistry, and surface charge can be specified to optimize efficiency for a given application. Consequently, interdisciplinary researchers have focused on producing biocompatible materials, production technologies, or new formulations for efficient loading, and high stability. The effects of design parameters can be studied in vitro, in vivo, or using computational models, with the goal of understanding how they affect nanoparticle biophysics and their interactions with cells. The present review summarizes the advances and technologies in the production and design of cancer nanomedicines to achieve clinical translation and commercialization. We also highlight existing challenges and opportunities in the field.

Gastroretentive Technologies in Tandem with Controlled-Release Strategies: A Potent Answer to Oral Drug Bioavailability and Patient Compliance Implications

There have been many efforts to improve oral drug bioavailability and therapeutic efficacy and patient compliance. A variety of controlled-release oral delivery systems have been developed to meet these needs. Gastroretentive drug delivery technologies have the potential to achieve retention of the dosage form in the upper gastrointestinal tract (GIT) that can be sufficient to ensure complete solubilisation of the drugs in the stomach fluids, followed by subsequent absorption in the stomach or proximal small intestine. This can be beneficial for drugs that have an “absorption window” or are absorbed to a different extent in various segments of the GIT. Therefore, gastroretentive technologies in tandem with controlled-release strategies could enhance both the therapeutic efficacy of many drugs and improve patient compliance through a reduction in dosing frequency. The paper reviews different gastroretentive drug delivery technologies and controlled-release strategies that can be combined and summarises examples of formulations currently in clinical development and commercially available gastroretentive controlled-release products. The different parameters that need to be considered and monitored during formulation development for these pharmaceutical applications are highlighted.

Studies on the in vitro ion exchange kinetics and thermodynamics and in vivo pharmacokinetics of the carbinoxamine-resin complex

The short half-life and bitter taste of carbinoxamine maleate² (CAM) lead to poor compliance by pediatric patients who are being treated for allergic rhinitis. To address these issues, carbinoxamine-resin complexes³ (CRCs) were prepared by ion exchange and then coated with Kollicoat SR 30D. The resultant microencapsulated carbinoxamine-resin complexes⁴ (MCRCs) were dispersed into the medium to obtain the final suspensions. The drug loading kinetics and thermodynamics of CRCs, anti-swelling mechanism of the impregnant in MCRCs, in vitro release, and in vivo pharmacokinetics of the suspensions were systematically evaluated. The drug loading process was found to obey a first-order kinetic process that was spontaneous, entropy-reduced and exothermic, and the diffusion of CAM into the resin was the rate-limiting step. During microencapsulation, the impregnant could create a certain buffer space to control the swelling of CRCs and maintain the coating film intact. The homemade preparations had release behaviors similar to that of the reference in vitro and achieved sustained release in vivo. The low drug loading preparation had a higher relative bioavailability of 109% owing to its faster release and better dispersibility. Therefore, the suspensions based on MCRCs could be successfully applied to treating allergic rhinitis in children.

Development, Optimization, and Evaluation In Vitro/In Vivo of Oral Liquid System for Synchronized Sustained Release of Levodopa/Benserazide

To enhance efficiency, convenience, and safety of Parkinson's disease (PD) treatment for geriatric patients, an advanced suspension of Levodopa/Benserazide hydrochloride (LD/BH) has been prepared by cation-exchange resin and used to synchronize sustained release of LD and BH by optimizing coating parameters and prescription. For the purpose, LD and BH were immobilized on the surface of cation-exchange resin, respectively. Based on HPLC results, the cation-exchange resin showed high loading capacity. The studies on drug loading mechanism indicated that both drugs were immobilized by electrostatic interaction rather than physical adsorption. After PEG modification, pretreated drug-resin complexes were coated by emulsion-solvent evaporation method. In order to control drug release in a sustained manner, coating parameters of drug-resin microcapsules were optimized respectively by single-factor analysis. Further, coating prescription of the microcapsules was optimized to synchronize sustained release of LD and BH in vitro by orthogonal design. Utilizing optimal LD-resin microcapsules and BH-resin microcapsules, LD/BH suspension, containing both of them, was prepared by an optimal formulation and characterized by accelerated test and pharmacokinetic study in vivo. The accelerated test confirmed high stability of LD/BH suspension. According to pharmacokinetic results in vivo, in contrast with LD/BH commercial tablets, LD/BH suspensions did not only synchronize sustained release of both drugs but also show good bioequivalence. As LD/BH sustained release suspension can synchronize sustained release of multiple active ingredients by oral administration, the suspension presents promising oral dosage forms for geriatric patients with PD. An advanced Levodopa/Benserazide hydrochloride (LD/BH) suspension, prepared by cation-exchange resin and optimized microencapsulation, synchronizes sustained releases of LD and BH in vivo to benefit Parkinson's disease treatment for geriatric patients.

Current State and Future Perspectives on Gastroretentive Drug Delivery Systems

In recent years, many attempts have been made to enhance the drug bioavailability and therapeutic effectiveness of oral dosage forms. In this context, various gastroretentive drug delivery systems (GRDDS) have been used to improve the therapeutic efficacy of drugs that have a narrow absorption window, are unstable at alkaline pH, are soluble in acidic conditions, and are active locally in the stomach. In this review, we discuss the physiological state of the stomach and various factors that affect GRDDS. Recently applied gastrointestinal technologies such as expandable, superporous hydrogel; bio/mucoadhesive, magnetic, ion-exchange resin; and low- and high-density-systems have also been examined along with their merits and demerits. The significance of in vitro and in vivo evaluation parameters of various GRDDS is summarized along with their applications. Moreover, future perspectives on this technology are discussed to minimize the gastric emptying rate in both the fasted and fed states. Overall, this review may inform and guide formulation scientists in designing the GRDDS.

Effect of drug-ion exchange resin complex in betahistine hydrochloride orodispersible film on sustained release, taste masking and hygroscopicity reduction

Orodispersible film (ODF) is a widely used oral solid dosage form. However, it's not suitable for drugs with short half-life, bitterness and strong hygroscopicity. The present study aims to develop a sustained release and stable betahistine hydrochloride ODF without bitterness. Drug-resin complex (IRDC) was prepared using batch method. In vitro dissolution experiment, e-Tongue and hygroscopicity experiment were conducted to compare the differences between ODF containing IRDC and ODF containing betahistine hydrochloride. Drug release kinetics showed that the diffusion of drug in IRDC was the rate-limiting step of drug release. DSC and FT-IR were conducted to explore the molecular mechanism of taste masking and hygroscopicity reduction. It turned out that taste masking was attributed to the ionic interaction between drug and resin and the slow dissolution of drug from IRDC. The site where drug form hydrogen bonds with water molecular was occupied by drug-resin interaction leading to hygroscopicity reduction. In summary, in this study we not only developed a betahistine hydrochloride ODF with good properties but also explored the effect of drug-resin interaction on sustained release, taste masking and hygroscopicity reduction.

Improved therapeutic potential of tapentadol employing cationic exchange resins as carriers in neuropathic pain: evidence from pharmacokinetic and pharmacodynamics study

Current investigation was endeavoured to overcome problem of poor palatability and bioavailability of centrally acting analgesic, tapentadol (TAP) by formulating controlled release drug-resin complexes (DRCs). The technology encompassed in preparation of DRCs involved chemisorption of TAP to weak cationic resins (KyronT-134 and Tulsion335) by batch method. Various formulation variables like drug-resin ratio, pH, resin activation and swelling time were optimized to achieve maximum drug loading in DRCs. FT-IR, DSC, pXRD, in vitro release study under bio-relevant condition of mouth and in vivo sensory taste evaluation established formation of taste masked DRC whereas dissolution study assured prolonged drug release behaviour of optimized DRC. Among DRCs, TAP-KyronT-134 complex exhibited higher drug loading (80.89 ± 4.56%), stability and prolonged release profile (10 h) without any detectable amount of drug release under salivary conditions. Pharmacokinetic studies in wistar rats revealed increased Tmax (2.67-fold), MRT (1.94-fold), elimination half-life (2.79-fold) and relative oral bioavailability (2.62-fold) of TAP on oral administration of optimized formulation compared to TAP solution. Furthermore, pharmacodynamics study confessed higher potential of DRC in attenuating chronic injury induced tactile allodynia for prolonged duration. In conclusion, the method developed is easily scalable and holds potential for commercialization with an evidence of obtaining more efficacious neuropathic pain management therapy.

Preparation and Evaluation of Taste Masking Iron Suspension: Taking Advantage of Weak Cationic Exchange Resin

The objective of this study is to use weak acid cation exchange resin to mask the taste and eliminate the teeth staining problems of ferrous sulfate liquid preparations for use in pediatrics. Amberlite IPR64 was loaded by Fe(II). Then, different suspensions of the iron-resin complex were prepared using various polymers as the suspending agents, and sorbitol as well as sucrose as sweeteners. Physical stability, rheological assessment, kinetics of Fe(II) release, and taste evaluation of suspensions were studied. The results implied that the prepared iron suspension was more stable when xanthan gum is used as the suspending agent. It was also shown that iron release in 0.7% NaCl (similar to saliva) was very negligible compared to relatively quick release in acidic medium (resembled the stomach). Overall, the volunteers confirmed that the formulations were successful in iron taste masking. The pH-dependent process of ion exchange by weak cationic resins opens an attractive approach to access a taste-masked iron suspension for infants.

Carboxymethylinulin-Chitosan Nanoparticles for the Delivery of Antineoplastic Mitoxantrone

Mitoxantrone (MTX) is an antineoplastic agent whose use is limited by serious side effects on non-neoplastic cells. The aim of this study was the development of a new drug release system using an ionotropic gelation technique for microencapsulation of MTX in chitosan-carboxymethylinulin nanoparticles (CCInp), followed by evaluation of their cytotoxic effects on neoplastic MDA-MB-231 and non-neoplastic NIH3T3 cell lines. The CCInp were prepared through a new reliable method for easy functionalization of both inulin and chitosan. Both unloaded and drug-loaded nanoparticles were characterized by transmission electron microscopy (TEM) and dynamic light scattering (DLS) and showed a spherical morphology with an average hydrodynamic diameter between 40 and 80 nm. Both nanoparticles were stable and easily degraded by lysozyme. MTX-loaded nanoparticles led to a greater mortality of MDA-MB-231 relative to free drug due to the ability of the nanoparticles to accumulate preferentially in neoplastic cells. The developed drug release system retains the ability to kill MDA-MB-231 cells in vitro, improving the survival of NIH3T3 cells.

Nanostructured Lipid Carriers Loaded with Baicalin: An Efficient Carrier for Enhanced Antidiabetic Effects

Context:

Recent studies have demonstrated that baicalin has antihyperglycemic effects by inhibiting lipid peroxidation. Baicalin is low hydrophilic and poorly absorbed after oral administration. Thus, a suitable formulation is highly desired to overcome the disadvantages of baicalin.

Objective:

The objective of this work was to prepare baicalin-loaded nanostructured lipid carriers (B-NLCs) for enhanced antidiabetic effects.

Materials and Methods:

B-NLCs were prepared by high-pressure homogenization method using Precirol as the solid lipid and Miglyol as the liquid lipid. The properties of the NLCs, such as particle size, zeta potential (ZP), and drug encapsulation efficiency (EE), were investigated. The morphology of NLCs was observed by transmission electron microscopy. In addition, drug release and antidiabetic activity were also studied.

Results:

The results revealed that B-NLCs particles were uniformly in the nanosize range and of spherical morphology with a mean size of 92 ± 3.1 nm, a ZP of −31.35 ± 3.08 mV, and an EE of 85.29 ± 3.42%. Baicalin was released from NLCs in a sustained manner. In addition, B-NLCs showed a significantly higher antidiabetic efficacy compared with baicalin.

Conclusion:

B-NLCs described in this study are well-suited for the delivery of baicalin.

SUMMARY

Currently, herbal medicines have attracted increasing attention as a complementary approach for type 2 diabetes

Baicalin has antihyperglycemic effects by inhibiting lipid peroxidation

A suitable formulation is highly desired to overcome the disadvantages (poor solubility and low bioavailability) of baicalin

Nanostructured lipid carriers could enhance the antidiabetic effects of baicalin.

Abbreviations used: B-NLCs: Baicalin-Loaded Nanostructured Lipid Carriers, B-SUS: Baicalin Water Suspension, EE: Encapsulation Efficiency, FBG: Fasting Blood Glucose, HbAlc: Glycosylated Hemoglobin, HPLC: High-performance Liquid Chromatography; NLCs: Nanostructured Lipid Carriers, PI: Polydispersity Index, SD: Sprague-Dawley, SLNs: Solid lipid nanoparticles, STZ: Streptozotocin, TC: Total cholesterol, TEM: Transmission Electron Microscope, TG: Total Triglyceride, ZP: Zeta Potential.

Formulation of venlafaxine for once daily administration using polymeric material hybrids

OBJECTIVE

Controlled release venlafaxine for once daily administration.

METHODS

Drug resin complexation followed by polymer encapsulation. A 4(1).2(1) factorial design was used to study the effect of polymer type and core: coat ratio on the release profile and kinetics. Polymer combinations were tried for optimisation adapting the desIMNCility function. The optimised formula was tested in rabbits against commercial extended release capsules.

RESULTS

Poly-epsilon-caprolactone, poly(d, l-lactide-co-glycolide) ester and poly(d, l-lactide) ester polymers were more efficient in lowering the release rate and the initial burst release than Eudragit(®)RS100. Encapsulation at 1:1 ratio ensured complete coats and drug release sustainment. Formula prepared using 50:50 PLA/Eudragit at 1:1 ratio sustained the drug release up to 24 h with low burst release. This formula had higher venlafaxine absorption in rabbits compared to the commercial capsules.

CONCLUSIONS

The optimised formula is superior to the available once-daily trials regarding enhanced bioavailability, dosage form versatility and ease of scaling up.

Advances in oral controlled drug delivery: the role of drug-polymer and interpolymer non-covalent interactions

INTRODUCTION

After more than four decades of intense research, oral controlled drug delivery systems (DDSs) still represent a topic of major interest for pharmaceutical scientist and formulators. This can be explained in part by considering the economic value of oral DDSs whose market accounts for more than half of the overall drug delivery market. Polymeric systems based on drug-polymer non-covalent interaction represent a limited, but growing part of the field. Despite the large amount of literature and published reviews covering specific aspects, there is still need for a review of the relevant literature providing a general picture of the topic.

AREAS COVERED

The present review aims at presenting the latest findings in drug-polymer and interpolymer non-covalent interactions in oral controlled delivery while providing a specific perspective and a critical point of view, particularly on the tools and methods used for the study of these DDSs. Four main sections are considered: i) ionic interactions between drugs and polymers; ii) interpolymer complexes; iii) hydrogen bond; and iv) hydrophobic interactions.

EXPERT OPINION

The largest part of the scientific literature deals with systems based on drug-polymer ionic interactions while hydrogen bonding and hydrophobic interaction though, very promising, are more difficult to exploit, and therefore less studied. An accurate and exhaustive representation of the specific role of the chemical functions in establishing predictable interactions between drug and polymers is still required.

Formulation and evaluation of meloxicam oral disintegrating tablet with dissolution enhanced by combination of cyclodextrin and ion exchange resins

CONTEXT

The bitter taste of drug is masked by the exchange of ionized drugs with counter ions of ion exchange resin, forming "resinate". Cyclodextrin reduces the unpleasant taste and enhances the drug solubility by encapsulating drug molecules into its central cavity.

OBJECTIVE

Oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin was developed, to mask the bitter taste and enhance drug dissolution.

METHODS

Meloxicam (MX) was selected as a model drug. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste and stability.

RESULTS AND DISCUSSION

The tablet hardness was ∼3 kg/in(2), and the friability was <1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60 s, which is the acceptable limit for ODTs. These results were corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste. In addition, this tablet was stable at least 6 months.

CONCLUSIONS

The combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste and enhance the dissolution of drugs that are weakly soluble in water.

pH-responsive controlled release of epirubicin from Fe@Si-PW hybrid nanoparticles

An efficient drug delivery system has been fabricated through an electrostatic interaction between epirubicin and H3PW12O40-functionalized silica encapsulated maghemite nanoparticles. The obtained nanoparticles were characterized for morphology, size distribution, drug loading efficiency, drug content and drug release behavior. Our results indicate that the hybrid nanoparticles possess high adsorption capacity for epirubicin (20.6wt.%) and high drug loading efficiency (82.6%). The drug release is greater in acetate buffer (95.8%) as compared to phosphate buffered saline (47.5%). The pH-responsive release of the hybrid drug carrier and high drug loading efficiency are its advantages as a promising carrier.

Loading and release of amine drugs by ion-exchange fibers: role of amine type

With more production and application of ion-exchange fibers (IEFs), it becomes necessary to understand the interaction between IEFs and amine compounds, an important group of organic drugs and structural components of large organic molecules in biological systems. However, so far few experimental studies have been conducted to systematically investigate the exchanging mechanism of amine compounds to IEFs. Therefore, 15 amine drugs were selected to investigate the effect of amine type on the loading and release of them from the related IEFs. Loading affinity of these drugs by IEFs decreased in the order of secondary, tertiary, and primary. The following items: basicity, aromaticity, molar volume, rotatability, and so on, were emphatically discussed to address the underlying mechanism of drug loading and releasing extent and rate of IEFs. It was evident that strong alkaline drugs strengthened the ionic bond between the amine groups and IEFs, and thus the loading affinity. These results will advance the understanding of the exchanging behavior of IEFs in the drug delivery system.

Meloxicam taste-masked oral disintegrating tablet with dissolution enhanced by ion exchange resins and cyclodextrin

The purpose of this study was to develop taste-masked oral disintegrating tablets (ODTs) using the combination of ion exchange resin and cyclodextrin, to mask the bitter taste and enhance drug dissolution. Meloxicam (MX) was selected as a model drug with poor water solubility and a bitter taste. Formulations containing various forms of MX (free drug, MX-loaded resin or resinate, complexes of MX and 2-hydroxypropyl-β-cyclodextrin (HPβCD) or MX/HPβCD complexes, and a mixture of resinate and MX/HPβCD complexes) were made and tablets were prepared by direct compression. The ODTs were evaluated for weight variation, thickness, diameter, hardness, friability, disintegration time, wetting time, MX content, MX release, degree of bitter taste, and stability. The results showed that thickness, diameter, weight, and friability did not differ significantly for all of these formulations. The tablet hardness was approximately 3 kg/in.(2), and the friability was less than 1%. Tablets formulated with resinate and the mixture of resinate and MX/HPβCD complexes disintegrated rapidly within 60 s, which is the acceptable limit for ODTs. These results corresponded to the in vivo disintegration and wetting times. However, only tablets containing the mixture of resinate and MX/HPβCD complexes provided complete MX dissolution and successfully masked the bitter taste of MX. In addition, this tablet was stable at least 6 months. The results from this study suggest that the appropriate combination of ion exchange resin and cyclodextrin could be used in ODTs to mask the bitter taste of drug and enhance the dissolution of drugs that are weakly soluble in water.

Tamoxifen-loaded nanostructured lipid carrier as a drug delivery system: characterization, stability assessment and cytotoxicity

Cancer nanotherapeutics is beginning to overwhelm the global research and viewed to be the revolutionary treatment regime in the medical field. This investigation describes the development of a stable nanostructured lipid carrier (NLC) system as carrier for Tamoxifen (TAM). The TAM-loaded NLC (TAM-NLC) developed with 200mg of TAM showed a spherical particle with the size of 46.6nm, polydispersity index of 0.267, entrapment efficiency of 99.74% and with the zeta potential of -23.78mV. Besides, the equivalent cytotoxicity of TAM and TAM-NLC to human (MCF-7) and mice (4T1) mammary breast cancer cell lines were observed. Incubating the formulation at the physiological pH resulted into reduced Ostwald ripening rate but without any significant change in the absorptivity. When coupled with the measurements of zeta potential and Ostwald ripening rate, the absorbance assay may be used to predict the long-term stability of drug-loaded nanoparticle formulations. The results of the study also suggest that TAM-NLC is a promising drug delivery system for breast cancer therapy. This is the first encouraging report on the in vitro effect of TAM-NLC against human and mouse mammary adenocarcinoma cell lines.

Improvement of drug loading onto ion exchange resin by cyclodextrin inclusion complex

CONTEXT

Ion exchange resins have ability to exchange their counter ions for ionized drug in the surrounding medium, yielding "drug resin complex." Cyclodextrin can be applied for enhancement of drug solubility and stability.

OBJECTIVE

Cyclodextrin inclusion complex of poorly water-soluble NSAIDs, i.e. meloxicam and piroxicam, was characterized and its novel application for improving drug loading onto an anionic exchange resin, i.e. Dowex® 1×2, was investigated.

METHODS

β-Cyclodextrin (β-CD) and hydroxypropyl β-cyclodextrin (HP-β-CD) were used for the preparation of inclusion complex with drugs in solution state at various pH. The inclusion complex was characterized by phase solubility, continuous variation, spectroscopic and electrochemistry methods. Then, the drug with and without cyclodextrin were equilibrated with resin at 1:1 and 1:2 weight ratio of drug and resin.

RESULTS AND DISCUSSION

Solubility of the drugs was found to increase with increasing cyclodextrin concentration and pH. The increased solubility was explained predominantly due to the formation of inclusion complex at low pH and the increased ionization of drug at high pH. According to characterization studies, the inclusion complex was successfully formed with a 1:1 stoichiometry. The presence of cyclodextrin in the loading solution resulted in the improvement of drug loading onto resin.

CONCLUSIONS

Enhancing drug loading onto ion-exchange resin via the formation of cyclodextrin inclusion complex is usable in the development of ion-exchange based drug delivery systems, which will beneficially reduce the use of harmful acidic or basic and organic chemicals.

Reversible and pH-dependent weak drug-excipient binding does not affect oral bioavailability of high dose drugs

Objectives

Drug-excipient binding can affect in-vitro drug release. Literature suggests that drug-excipient ionic binding interaction that is not disrupted by physiological salt concentration in the dissolution medium can impact a drug's oral bioavailability. We investigated whether nondisruption of interaction by physiological salt concentration was an adequate predictor of its biorelevance using the binding of a model amine high dose drug brivanib alaninate (BA) to croscarmellose sodium (CCS) as an example.

Methods

BA was formulated into an immediate release tablet using CCS as disintegrant by a wet granulation process. In-vitro drug release was carried out as a function of pH and buffer concentration of the medium. BA-CCS binding was studied in buffer solution and data fitted to a Langmuir isotherm. A simulation model and an isothermal titration calorimetry method were developed to assess the bioavailability risk and strength of drug-excipient binding interaction, independent of physiological salt concentration consideration.

Key findings

BA-CCS binding was pH-dependent, reversible, ionic, and not disrupted by increasing the buffer concentration in the dissolution medium. Absorption simulation predictions of no effect of CCS binding on BA's bioavailability were confirmed by a monkey pharmacokinetic study.

Conclusions

A pH-dependent and reversible weak drug-excipient binding interaction is unlikely to affect the oral bioavailability of high dose drugs.