Effect of oppositely charged polymer and dissolution medium on swelling, erosion, and drug release from chitosan matrices

Designing and In Vitro Characterization of pH-Sensitive Aspartic Acid-Graft-Poly(Acrylic Acid) Hydrogels as Controlled Drug Carriers

Acetaminophen is an odorless and white crystalline powder drug, used in the management of fever, pain, and headache. The half-life of acetaminophen is very short; thus, multiple intakes of acetaminophen are needed in a day to maintain a constant pharmacological action for an extended period of time. Certain severe adverse effects are produced due to the frequent intake of acetaminophen, especially hepatotoxicity and skin rashes. Therefore, a drug carrier system is needed which not only prolongs the release of acetaminophen, but also enhances the patient compliance. Therefore, the authors prepared novel aspartic acid-graft-poly(acrylic acid) hydrogels for the controlled release of acetaminophen. The novelty of the prepared hydrogels is based on the incorporation of pH-sensitive monomer acrylic acid with polymer aspartic acid in the presence of ethylene glycol dimethacrylate. Due to the pH-sensitive nature, the release of acetaminophen was prolonged for an extended period of time by the developed hydrogels. Hence, a series of studies was carried out for the formulated hydrogels including sol-gel fraction, FTIR, dynamic swelling, polymer volume analysis, thermal analysis, percent porosity, SEM, in vitro drug release studies, and PXRD analysis. FTIR analysis confirmed the grafting of acrylic acid onto the backbone of aspartic acid and revealed the development of hydrogels. The thermal studies revealed the high thermal stability of the fabricated hydrogels as compared to pure aspartic acid. An irregular surface with a few pores was indicated by SEM. PXRD revealed the amorphous state of the developed hydrogels and confirmed the reduction in the crystallinity of the unreacted aspartic acid by the formulated hydrogels. An increase in gel fraction was observed with the increasing concentration of aspartic acid, acrylic acid, and ethylene glycol dimethacrylate due to the availability of a high amount of free radicals. The porosity study was influenced by the various compositions of developed hydrogels. Porosity was increased due to the enhancement in the concentrations of aspartic acid and acrylic acid, whereas it decreased with the increase in ethylene glycol dimethacrylate concentration. Similarly, the pH-responsive properties of hydrogels were evaluated by dynamic swelling and in vitro drug release studies at two different pH levels (1.2 and 7.4), and a greater dynamic swelling and acetaminophen release were exhibited at pH 7.4 as compared to pH 1.2. An increase in swelling, drug loading, and drug release was seen with the increased incorporation of aspartic acid and acrylic acid, whereas a decrease was detected with the increase in the concentration of ethylene glycol dimethacrylate. Conclusively, the formulated aspartic acid-based hydrogels could be employed as a suitable nonactive pharmaceutical ingredient for the controlled delivery of acetaminophen.

Nanodesigning of multifunctional quantum dots and nanoparticles for the treatment of fibrosarcoma

AIM

An effective, dual drug(DD) loaded nanocarrier system (nano particle(NP), quantum dots(QDs)) having two active substances was aimed to develop for the treatment of fibrosarcoma.

METHODS

Zinc oxide(ZnO) QDs were produced using zinc acetate dehydrate as a precursor, were incorporated with chitosan(Ch), and finally decorated with PEG-linked folic acid and were found to be effective after imatinib mesylate(IM) and dexketoprofen trometamol(DT) were loaded. Characterizations, invitro drug releases, cell toxicities, penetrations through cell lines and in-vivo animal tests of the prepared nanosystems were performed.

RESULTS

The size of hybrid nanoparticles were 168.6 ± 48.8nm, surface charge was -35.8 ± 0.26mV. The encapsulation efficiency was 75% for IM and 99% for DT. DD-functionalized QDChNPs and lyophilized functionalized QDChNPs in capsules slowed down tumor growth by up to 76.5 % and 88.7 %.

CONCLUSIONS

Our results demonstrate that developed hybrid nanoparticles are highly effective. This hybrid system gathers many of the advantages of nanotechnology into one form.

Preparation and evaluation of polymeric beads composed of Chitosan–Gellan Gum–Gum Ghatti/-Gum Karaya polyelectrolyte complexes as polymeric carrier for enteric sustained delivery of Diclofenac sodium

Background

An enteric coating is a multistep technique that involves deposition of a polymeric barrier over uncoated orally administered tablets to prevent them from dissolving or disintegrating in the stomach. However, as soon as the coating dissolves in the alkaline environment of intestine, the whole of the drug come in direct contact with gastric mucosa leading to irritation to distal parts of the gastrointestinal tract (GIT). Considering the above facts, there is clear need to develop a simple and effective enteric release formulation for gastric irritant drugs like Diclofenac sodium (DS). The goal of this study was to create enteric release polymeric polyelectrolyte complex (PEC) beads made up of cationic Chitosan (CH) and anionic Gellan Gum (GG) for sustained DS delivery to the intestine. The beads were prepared by extruding a solution of GG and Gum Ghatti (GT) or GG and Gum Karaya (GK) bearing DS into CH solution in 1% w/v acetic acid, with the help of a syringe fitted with a 18 gauge hypodermic needle.

Results

Instantly created spherical beads were dried in a hot air oven 60 °C overnight. In 0.1 M HCl and 6.8 pH phosphate buffer, the dried beads were tested for drug entrapment in the beads, in vitro swelling of beads and in vitro drug release studies from the beads. The % drug entrapment efficiencies (% DEE) of these PEC beads ranged from 59.54 ± 2.09 to 81.03 ± 4.22%. In 0.1 M HCl, the PEC beads swelled the least in vitro, but expanded significantly in phosphate buffer (pH 6.8). The in vitro release of Diclofenac sodium from different PEC beads in 0.1 M HCl was found to be less than 7.5 percent, whereas the release was sustained for 6 h in phosphate buffer (pH 6.8).

Conclusions

From the experimental data, it may be concluded that these PEC beads can be useful as potential multiple-unit enteric release polymeric carrier systems for sustained delivery of gastric irritant drugs like Diclofenac sodium.

Preclinical evaluation of methotrexate-loaded polyelectrolyte complexes and thermosensitive hydrogels as treatment for rheumatoid arthritis

This work proposes new methotrexate (MTX) loaded drug delivery systems (DDS) to treat rheumatoid arthritis via the intra-articular route: a poloxamer based thermosensitive hydrogel (MTX-HG), oligochitosan and hypromellose phthalate-based polyelectrolyte complexes (MTX-PEC) and their association (MTX-PEC-HG). MTX-PEC showed 470 ± 166 nm particle size, 0.298 ± 0.108 polydispersity index, +26 ± 2 mV and 74.3 ± 5.8% MTX efficiency entrapment and particle formation was confirmed by infrared spectroscopy and thermal analysis. MTX-HG and MTX-PEC-HG gelled at 36.7°C. MTX drug release profile was prolonged for MTX-HG and MTX-PEC-HG, and faster for MTX-PEC and free MTX. The in vivo effect of the MTX-DDSs systems was evaluated in induced arthritis rats as single intra-articular dose. The assessed parameters were the mechanical nociceptive threshold, the plasmatic IL-1β level and histological analysis of the tibiofemoral joint. MTX-HG and MTX-PEC-HG performance were similar to free MTX and worse than oral MTX, used as positive control. All DDSs showed some irritative effect, for which further studies are required. MTX-PEC was the best treatment on recovering cartilage damage and decreasing allodynia. Thus, MTX-PEC demonstrated potential to treat rheumatoid arthritis, with the possibility of decreasing the systemic exposure to the drug.

Bucco-Adhesive Film as a Pediatric Proper Dosage Form for Systemic Delivery of Propranolol Hydrochloride: In-vitro and in-vivo Evaluation

Objective

To formulate and assess bucco-adhesive films of propranolol hydrochloride for pediatric use.

Methods

Different films were formulated adopting mucin, polyvinyl alcohol, chitosan and carbopol. A drug/polymer compatibility study was conducted adopting differential scanning calorimetry and Fourier transform infrared spectroscopy. The prepared films were physically investigated for variation of weight, propranolol content, thickness, surface pH, proportion of moisture, folding endurance and mucoadhesion. In vitro drug release study and kinetic analysis of the corresponding data have been conducted. The optimized formulation was selected for a bioavailability study using albino rabbits and adopting a developed HPLC method. The pharmacokinetic parameters of the drug were calculated following administration of the optimized film and the corresponding marketed oral tablets to albino rabbits.

Key Finding

The compatibility study revealed the absence of drug/polymer interaction. The film formulations had suitable mucoadhesive and mechanical properties. The optimized formulation exhibited reasonable drug release that followed Higuchi diffusion pattern. The calculated AUC0-8h presented an enhancement in the bioavailability of propranolol hydrochloride from the selected film formulation by 1.9 times relative to the marketed propranolol oral tablets.

Conclusion

These findings support that propranolol hydrochloride bucco-adhesive film can be considered as a proper effective dosage form for pediatric delivery.

Mucoadhesive Chitosan Delivery System with Chelidonii Herba Lyophilized Extract as a Promising Strategy for Vaginitis Treatment

Chelidonium majus (also known as celandine) contains pharmacologically active compounds such as isoquinoline alkaloids (e.g., chelidonine, sanguinarine), flavonoids, saponins, carotenoids, and organic acids. Due to the presence of isoquinoline alkaloids, Chelidonii herba extracts are widely used as an antibacterial, antifungal, antiviral (including HSV-1 and HIV-1), and anti-inflammatory agent in the treatment of various diseases, while chitosan is a biocompatible and biodegradable carrier with valuable properties for mucoadhesive formulations preparation. Our work aimed to prepare mucoadhesive vaginal drug delivery systems composed of Chelidonii herba lyophilized extract and chitosan as an effective way to treat vaginitis. The pharmacological safety of usage of isoquinoline alkaloids, based on MTT test, were evaluated for the maximum doses 36.34 ± 0.29 µg/mL and 0.89 ± 1.16 µg/mL for chelidonine and sanguinarine, respectively. Dissolution rate profiles and permeability through artificial membranes for chelidonine and sanguinarine after their introduction into the chitosan system were studied. The low permeability for used save doses of isoquinoline alkaloids and results of microbiological studies allow confirmation that system Chelidonii herba lyophilized extract chitosan 80/500 1:1 (w/w) is a promising strategy for vaginal use. Ex vivo studies of mucoadhesive properties and evaluation of tableting features demonstrated that the formulation containing Chelidonii herba lyophilized extract (120.0 mg) with chitosan (80/500—100.0 mg) and polymer content (HPMC—100.0 mg, microcrystalline cellulose—50.0 mg, lactose monohydrate—30.0 mg and magnesium stearate—4.0 mg) is a vaginal dosage form with prolonging dissolution profile and high mucoadhesion properties (up to 4 h).

Lipopolysaccharide Polyelectrolyte Complex for Oral Delivery of an Anti-tubercular Drug

Anti-tuberculosis drug delivery has remained a challenge due to inconsistent bioavailability and inadequate sustained-release properties leading to treatment failure. To resolve these drawbacks, a lipopolysaccharide polyelectrolyte complex (PEC) encapsulated with rifampicin (RIF) (as the model drug) was fabricated, using the solvent injection technique (SIT), with soy lecithin (SLCT), and low-molecular-weight chitosan (LWCT). The average particle size and surface charge of RIF-loaded PEC particulates was 151.6 nm and + 33.0 nm, respectively, with noted decreased particle size and surface charge following increase in SLCT-LWCT mass ratio. Encapsulation efficiency (%EE) and drug-loading capacity (%LC) was 64.25% and 5.84%, respectively. Increase in SLCT-LWCT mass ratio significantly increased %EE with a marginal reduction in %LC. In vitro release studies showed a sustained-release profile for the PEC particulate tablet over 24 h (11.4% cumulative release) where the dominant release mechanism involved non-Fickian anomalous transport shifting towards super case II release as SLCT ratios increased (6.4% cumulative release). PEC-tablets prepared without SIT presented with rapid Fickian-diffusion-based drug release with up to 90% RIF release within 4 h. Ex vivo permeability studies revealed that lipopolysaccharide PEComplexation significantly increased the permeability of RIF by ~ 2-fold within the 8-h study period. These results suggest successful encapsulation of RIF within a PEC structure while imparting increased amorphic regions, as indicated by x-ray diffraction, for potential benefits in improved drug dissolution, bioavailability, and dosing.

Influences of novel microwave drying on dissolution of new formulated naproxen sodium

Drying of a pharmaceutical composition is an important step during its processing, which can affect its quality attributes including its texture, dispersion of the drug within the formulation, drug dissolution kinetics and eventually the drug's efficacy. This study presents the influence of varying drying techniques on the textural properties of the wet granulated formulation consisting of the drug naproxen sodium (NapSod) during the drying process. A new pharmaceutical formulation consisting of the NapSod drug was prepared by wet granulation and dried by novel microwave drying (MW), freeze drying (FD), vacuum drying (VD), and convective drying (CD) techniques before being processed in the form of tablets. The dissolution rate of NapSod from the tablet was measured in gastric (pH = 1.3) and intestinal fluid (pH = 6.8) mediums. The drug release was found to be influenced by the specific surface area, size distribution and the crystalline structure of dried particles, which were found to vary with the type of drying technique used as confirmed by the results of XRD, FTIR, SEM and particle size analyses. This study shows that using microwave technique to dry pharmaceutical granules containing a polar drug, such as NapSod, is an efficient and economical process, which can maintain the drug release at an appropriate rate to realize its desired pharmaceutical effect.

Novel microwave mediated drying of naproxen sodium has been shown as an efficient drying technique as well as exhibiting a critical role in improving the dissolution kinetics.

Effect of Formulation and Process Parameters on Chitosan Microparticles Prepared by an Emulsion Crosslinking Technique

There are many studies about the synthesis of chitosan microparticles; however, most of them have very low production rate, have wide size distribution, are difficult to reproduce, and use harsh crosslinking agents. Uniform microparticles are necessary to obtain repeatable drug release behavior. The main focus of this investigation was to study the effect of the process and formulation parameters during the preparation of chitosan microparticles in order to produce particles with narrow size distribution. The technique evaluated during this study was emulsion crosslinking technique. Chitosan is a biocompatible and biodegradable material but lacks good mechanical properties; for that reason, chitosan was ionically crosslinked with sodium tripolyphosphate (TPP) at three different ratios (32, 64, and 100%). The model drug used was acetylsalicylic acid (ASA). During the preparation of the microparticles, chitosan was first mixed with ASA and then dispersed in oil containing an emulsifier. The evaporation of the solvents hardened the hydrophilic droplets forming microparticles with spherical shape. The process and formulation parameters were varied, and the microparticles were characterized by their morphology, particle size, drug loading efficiency, and drug release behavior. The higher drug loading efficiency was achieved by using 32% mass ratio of TPP to chitosan. The average microparticle size was 18.7 μm. The optimum formulation conditions to prepare uniform spherical microparticles were determined and represented by a region in a triangular phase diagram. The drug release analyses were evaluated in phosphate buffer solution at pH 7.4 and were mainly completed at 24 h.

In Vivo Magnetic Resonance Imaging and Microwave Thermotherapy of Cancer Using Novel Chitosan Microcapsules

Herein, we develop a novel integrated strategy for the preparation of theranostic chitosan microcapsules by encapsulating ion liquids (ILs) and Fe3O4 nanoparticles. The as-prepared chitosan/Fe3O4@IL microcapsules exhibit not only significant heating efficacy in vitro under microwave (MW) irradiation but also obvious enhancement of T2-weighted magnetic resonance (MR) imaging, besides the excellent biocompatibility in physiological environments. The chitosan/Fe3O4@IL microcapsules show ideal temperature rise and therapeutic efficiency when applied to microwave thermal therapy in vivo. Complete tumor elimination is realizing after MW irradiation at an ultralow power density (1.8 W/cm(2)), while neither the MW group nor the chitosan microcapsule group has significant influence on the tumor development. The applicability of the chitosan/Fe3O4@IL microcapsules as an efficient contrast agent for MR imaging is proved in vivo. Moreover, the result of in vivo systematic toxicity shows that chitosan/Fe3O4@IL microcapsules have no acute fatal toxicity. Our study presents an interesting type of multifunctional platform developed by chitosan microcapsule promising for imaging-guided MW thermotherapy.

Gold nanoparticles enhance 5-fluorouracil anticancer efficacy against colorectal cancer cells

5-Fluorouracil (5-FU), an antimetabolite drug, is extensively used in the treatment solid tumors. However, its severe side effects limit its clinical benefits. To enhance 5-FU anticancer efficacy and reduce its side effects it was loaded onto gold nanoparticles (GNPs) using two thiol containing ligands, thioglycolic acid (TGA) and glutathione (GSH). The GNPs were prepared at different 5-FU/ligand molar ratios and evaluated using different techniques. Anticancer efficacy of 5-FU/GSH-GNPs was studied using flow cytometry in cancerous tissue obtained from patients having colorectal cancer. The GNPs were spherical in shape and had a size of ∼9-17nm. Stability of the GNPs and drug release were studied as a function of salt concentration and solution pH. Maximum 5-FU loading was achieved at 5-FU/ligand molar ratio of 1:1 and 2:1 for TGA-GNPs and GSH-GNPs, respectively. GNPs coating with pluronic F127 improved their stability against salinity. 5-FU release from GNPs was slow and pH-dependent. 5-FU/GSH-GNPs induced apoptosis and stopped the cell cycle progression in colorectal cancer cells. They also had a 2-fold higher anticancer effect compared with free 5-FU. These results confirm the potential of GNPs to enhance 5-FU anticancer efficacy.

Elucidation of release characteristics of highly soluble drug trimetazidine hydrochloride from chitosan-carrageenan matrix tablets

The aim of this study was to better understand the underlying drug release characteristics from matrix tablets based on the combination of chitosan (CS) and different types of carrageenans [kappa (κ)-CG, iota (ι)-CG, and lambda (λ)-CG]. Highly soluble trimetazidine hydrochloride (TH) was used as a model drug. First, characteristics of drug release from different formulations were investigated, and then in situ complexation capacity of CG with TH and CS was studied by differential scanning calorimetry and Fourier transform infrared spectroscopy. Erosion and swelling of matrix were also characterized to better understand the drug-release mechanisms. Effects of pH and ionic strength on drug release were also studied. It was found that not only ι-CG and λ-CG could reduce the burst release of TH by the effect of TH-CG interaction, CS-ι-CG- and CS-λ-CG-based polyelectrolyte film could further modify the controlled-release behavior, but not CS-κ-CG. High pH and high ionic strength resulted in faster drug release from CS-κ-CG- and CS-ι-CG-based matrix, but drug release from CS-λ-CG-based matrix was less sensitive to pH and ionic strength. In conclusion, CS-λ-CG-based matrix tablets are quite promising as controlled-release drug carrier based on multiple mechanisms.

An insight into the properties of Aegle marmelos pectin-chitosan cross-linked films

Pectin of Aegle marmelos (AP) ripe fruits processed in equal proportion with chitosan (CH) formed films that exhibited minimum swelling index and volume index on exposure to buffers of acidic and alkaline pH. Highest contact angle and spreading coefficient coupled with lowest work of adhesion in all buffers for this film suggested availability of limited number of functional groups for interaction with water molecules due to optimum cross-linking between -NH(3)(+) groups of CH and -COO(-) groups of AP. This contention was substantiated by the presence of almost negligible charge on this film. The endothermic transition ΔH characteristic of -NH(3)(+)-COO(-) cross-linking between groups in this film was observed to decrease by only 1% after its sequential exposure to pH 1.2 (3 h) and pH 7.4 (6 h). Furthermore, the absence of pores or erosion in the scanning electron photomicrograph suggested the versatility of this film due to its resistance to acidic and alkaline pH.

Reduced ulcerogenic potential and antiarthritic effect of chitosan-naproxen sodium complexes

The purpose of this research was to address the utility of naproxen sodium-chitosan spray-dried complexes for antiulcer and antiarthritic activities. The cold stress technique was used to examine the ulcerogenic potential of naproxen sodium (NPX) and spray-dried formulations in the different doses. The ulcerations reduced with the dose of spray-dried complexes of naproxen sodium and chitosan. The conspicuous hemorrhagic lesions were visible in the morphological features of the animal treated with naproxen 50 mg/kg (p.o.). Thus, the results suggest that the spray-dried naproxen sodium-chitosan complex (NPXF) was not corrosive to the gastric mucosa at high doses of 50, 100, and 200 mg/kg (p.o.) under stressful conditions. It is evident from the present investigation that NPXF does not possess any ulcerogenic potential in comparison to naproxen which, under stressful conditions, led to the hypersecretion of HCl, culminating to petichial hemorrhages in the gastric mucosa of the animals. The biphasic pattern was observed in the various arthritic parameters. The rise in paw volume, joint diameter, WBC count, arthritis score, and fall in body weight was significantly ameliorated in the animals treated with NPXF (5, 10, and 20 mg/kg, p.o). At the end of the study, slight erythema was visible in the naproxen-treated animals. However, no erythema, redness, or ulcers were visible in the animals treated with NPXF. Thus, the direct compression properties and reduced ulcerogenic activity, combined with the demonstrated solubilizing power and analgesic effect enhancer ability toward the drug, make naproxen sodium-chitosan spray-dried complexes particularly suitable for developing a reduced-dose, fast-release, solid oral dosage form of naproxen.

Differential contribution of Igepal and CnTAB micelles on the photophysics of nonsteroidal drug Naproxen

Spectroscopic studies of Naproxen (NP), a nonsteroidal drug have been carried out in well characterized, micellar media of cationic surfactants of a homologous series having general formula C(n)TAB (alkyl trimethyl ammonium bromide) and of nonionic surfactants of Igepal (Ig) series (poly(oxyethylene) nonyl phenol). The fluorescence behavior of the drug molecule in C(n)TAB micelles has been found to be opposite to that in Igepal micelles. The binding constants during probe micelle binding have been evaluated from relevant fluorescence data. Location and nature of the surrounding medium of the probe in micellar media have been ascertained from fluorescence quenching study. Fluorescence anisotropy parameter has been monitored for exploring the imposed motional restriction of the microenvironment around the probe. Contrasting behavior of the drug molecule has been observed in two different types of micelles. Based on the experimental and theoretical studies, an attempt has been made to explain the different behavior of the probe in different media.

Excipients with specialized functions for effective drug delivery

INTRODUCTION

There is a growing need for the development of pharmaceutical excipients that could improve product performance and overcome the shortcomings of new drug moieties, such as their poor solubility and membrane permeability, as well as to aid with modern manufacturing processes.

AREAS COVERED

Different types of functional excipients are discussed in this paper, in terms of their roles in modern dosage forms to optimize drug delivery and manufacturability. Functions of specialized excipients that are covered in this article include the enhancement of drug membrane permeability, the improvement of drug solubility and stability, the regulation of drug release in response to feedback mechanisms and assistance with the production of dosage forms.

EXPERT OPINION

Modern drug delivery systems rely on sophisticated excipients with multiple functions to improve overall product performance. The excipient market is expected to grow substantially with emerging trends in the development of these advanced drug delivery systems.

Effect of oppositely charged polymer and dissolution media on rheology of spray-dried ionic complexes

The purpose of this research was to address the utility of rheological study in understanding the influence of oppositely charged polymers on release of naproxen sodium encapsulated in chitosan particles. The interaction between oppositely charged kappa-carrageenan (kappa-Ca) and chitosan leads to relatively higher gel strength, which is proportional to the ability to retard the drug release at acidic pH. The oscillatory tests within the linear viscoelastic range where the stress is proportional to the applied strain were performed on the hydrated sample matrices containing chitosan-naproxen sodium spray-dried complexes and k-Ca or hydroxypropyl methylcellulose (HPMC) in various ratios. It was observed that the effect of pH change on the dynamic moduli in spray-dried complexes containing kappa-Ca was much stronger than that with HPMC reflecting presence of strong ionic interaction between kappa-Ca and chitosan. The combination of oppositely charged polymers in different ratios proved to be useful in modulating the rheological properties of the hydrated formulations and their release-retarding properties. Dynamic moduli can be used to measure gel strength and are significant for the interpretation of oral sustained release spray-dried complexes.

Release mechanisms behind polysaccharides-based famotidine controlled release matrix tablets

Polysaccharides, which have been explored to possess gelling properties and a wide margin of safety, were used to formulate single-unit floating matrix tablets by a direct compression technique. This work has the aim to allow continuous slow release of famotidine above its site of absorption. The floating approach was achieved by the use of the low density polypropylene foam powder. Polysaccharides (kappa-carrageenan, gellan gum, xyloglucan, and pectin) and blends of polysaccharides (kappa-carrageenan and gellan gum) and cellulose ethers (hydroxypropylmethyl cellulose, hydroxypropylcellulose, sodium carboxymethyl cellulose) were tried to modulate the release characteristics. The prepared floating tablets were evaluated for their floating behavior, matrix integrity, swelling studies, in vitro drug release studies, and kinetic analysis of the release data. The differential scanning calorimetry and Fourier transform infrared spectroscopy studies revealed that changing the polymer matrix system by formulation of polymers blends resulted in formation of molecular interactions which may have implications on drug release characteristics. This was obvious from the retardation in drug release and change in its mechanistics.

Effect of drying methods on swelling, erosion and drug release from chitosan-naproxen sodium complexes

The purpose of this research was to explore theapplication of ionic interactions between naproxen sodium (NS) and chitosan (CH) in complexes (NSC) prepared by tray drying (TD) and spray drying (SD) methods. Drug-polymer ratio (1:1) in the NSC was optimized on the basis of dialysis studies. The particulate systems of NSC were prepared by tray drying (TD) and spray drying (SD) methods. Release retarding polymers were added to the NSC and to the physical mixtures containing NS-CH and their effects on water uptake, matrix erosion and drug release at different pH were compared. Spray dried complexes (SDC) were spherical, free flowing, light and fine amorphous particles in contrast to the crystalline, hard, tenacious, irregularly shaped, denser tray dried complexes (TDC) with poor flowability. Differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD) and Fourier transform infrared (FTIR) patterns confirm the conversion of crystalline to high energy amorphous phase suitable for ionic interactions in NSC. Presence of release retarding polymers, kappa carrageenan and hydroxypropylmethylcellulose (HPMC) in the NSC compacts retarded the drug release and improved the matrix integrity. Carrageenan matrices exhibited more retardation than HPMC tablets. FTIR patterns, erosion, swelling and drug release from matrices support ionic interactions between NS and CH in NSC. The reasons for retarded drug release from the chitosan matrices at acidic pH include poor solubility of drug at acidic pH, formation of a rate limiting polymer gel barrier along the periphery of matrices and the ionic interactions between oppositely charged moieties.