Propranolol Hydrochloride Binding in Calcium Alginate Beads

Electro-hydrodynamic assisted synthesis of lecithin-stabilized peppermint oil-loaded alginate microbeads for intestinal drug delivery

Peppermint oil (PO) is the most prominent oil using in pharmaceutical formulations with its significant therapeutic value. In this sense, this oil is attracting considerable attention from the scientific community due to its traditional therapeutic claim, biological and pharmacological potential in recent research. An organic solvent-free and environment-friendly electrohydrodynamic assisted (EHDA) technique was employed to prepared PO-loaded alginate microbeads. The current study deals with the development, optimization, in vitro characterization, in vivo gastrointestinal tract drug distribution and ex-vivo mucoadhesive properties, antioxidant, and anti-inflammatory effects of PO-loaded alginate microbeads. The optimization results indicated the voltage and flow rate have a significant influence on microbeads size and sphericity factor and encapsulation efficiency. All these optimized microbeads showed a better drug release profile in simulated intestinal fluid (pH 6.8) at 2 h. However, a minor release was found in acidic media (pH 1.2) at 2 h. The optimized formulation showed excellent mucoadhesive properties in ex-vivo and good swelling characterization in intestine media. The microbeads were found to be well distributed in various parts of the intestine in in vivo study. PO-loaded alginate microbeads similarly showed potential antioxidant effects with drug release. The formulation exhibited possible improvement of irritable bowel syndrome (IBS) in MO-induced rats. It significantly suppressed proinflammatory cytokines, i.e., interleukin- IL-1β, and upregulated anti-inflammatory cytokine expression, i.e., IL-10. It would be a promising approach for targeted drug release after oral administration and could be considered an anti-inflammatory therapeutic strategy for treating IBS.

Encapsulation of Black Seed Oil in Alginate Beads as a pH-Sensitive Carrier for Intestine-Targeted Drug Delivery: In Vitro, In Vivo and Ex Vivo Study

Black seed oil (BSO) has been used for various therapeutic purposes around the world since ancient eras. It is one of the most prominent oils used in nutraceutical formulations and daily consumption for its significant therapeutic value is common phenomena. The main aim of this study was to develop alginate-BSO beads as a controlled release system designed to control drug release in the gastrointestinal tract (GIT). Electrospray technology facilitates formulation of small and uniform beads with higher diffusion and swelling rates resulting in process performance improvement. The effect of different formulation and process variables was evaluated on the internal and external bead morphology, size, shape, encapsulation efficiency, swelling rate, in vitro drug release, release mechanism, ex vivo mucoadhesive strength and gastrointestinal tract qualitative and quantitative distribution. All the formulated beads showed small sizes of 0.58 ± 0.01 mm (F8) and spherical shape of 0.03 ± 0.00 mm. The coefficient of weight variation (%) ranged from 1.37 (F8) to 3.93 (F5) ng. All formulations (F1–F9) were studied in vitro for release characteristics and swelling behaviour, then the release data were fitted to various equations to determine the exponent (ns), swelling kinetic constant (ks), swelling rate (%/h), correlation coefficient (r²) and release kinetic mechanism. The oil encapsulation efficiency was almost complete at 90.13% ± 0.93% in dried beads. The maximum bead swelling rate showed 982.23 (F8, r² = 0.996) in pH 6.8 and the drug release exceeded 90% in simulated gastrointestinal fluid (pH 6.8). Moreover, the beads were well distributed throughout various parts of the intestine. This designed formulation could possibly be advantageous in terms of increased bioavailability and targeted drug delivery to the intestine region and thus may find applications in some diseases like irritable bowel syndrome.

Formulation strategies for achieving high delivery efficiency of thymoquinone-containing Nigella sativa extract to the colon based on oral alginate microcapsules for treatment of inflammatory bowel disease

Nigella sativa extract (NSE) was incorporated in alginate microcapsules using aerosolisation and homogenisation methods, respectively, with the aim of delivering high concentrations of the active species, thymoquinone (TQ), directly to sites of inflammation in the colon following oral administration. Encapsulation of NSE was accomplished either by direct loading or diffusion into blank microparticles. Microcapsules in the size range 40-60 µm exhibited significantly higher NSE loading up to 42% w/w and encapsulation efficiency (EE) up to 63% when the extract was entrapped by direct encapsulation compared with 4.1 w/w loading, 6.2% EE when NSE was incorporated by diffusion loading. Sequential exposure of samples to simulated intestinal fluids (SIFs) revealed that the microcapsules suppressed NSE release in simulated gastric fluid (SGF) for 2 h and SIF for 4 h and liberated most of the NSE content (80%) in simulated colonic fluid (SCF) over 18 h. NSE released in SCF at 12 h exhibited antioxidant activity, when measured using the 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay at levels comparable with the activity of unencapsulated extract. These findings demonstrate the potential of oral alginate microcapsules as highly efficient, targeted carriers for colonic delivery of NSE in the treatment of inflammatory bowel disease.

A Comparison of Aerosolization and Homogenization Techniques for Production of Alginate Microparticles for Delivery of Corticosteroids to the Colon

Alginate microparticles incorporating hydrocortisone hemisuccinate were produced by aerosolization and homogenization methods to investigate their potential for colonic drug delivery. Microparticle stabilization was achieved by CaCl₂ crosslinking solution (0.5 M and 1 M), and drug loading was accomplished by diffusion into blank microparticles or by direct encapsulation. Homogenization method produced smaller microparticles (45-50 μm), compared to aerosolization (65-90 μm). High drug loadings (40% wt/wt) were obtained for diffusion-loaded aerosolized microparticles. Aerosolized microparticles suppressed drug release in simulated gastric fluid (SGF) and simulated intestinal fluid (SIF) prior to drug release in simulated colonic fluid (SCF) to a higher extent than homogenized microparticles. Microparticles prepared using aerosolization or homogenization (1 M CaCl₂, diffusion loaded) released 5% and 17% of drug content after 2 h in SGF and 4 h in SIF, respectively, and 75% after 12 h in SCF. Thus, aerosolization and homogenization techniques show potential for producing alginate microparticles for colonic drug delivery in the treatment of inflammatory bowel disease.

A novel impinging aerosols method for production of propranolol hydrochloride-loaded alginate gel microspheres for oral delivery

Propranolol hydrochloride was directly encapsulated in alginate gel microspheres (40-50 µm in diameter) using a novel method involving impinging aerosols of CaCl(2) cross-linking solution and sodium alginate solution containing the drug. Microspheres formulated using 0.1 M CaCl(2) exhibited the highest drug loading (14%, w/w of dry microspheres) with 66.5% encapsulation efficiency. Less than 4% and 35% propranolol release occurred from hydrated and dried microspheres, respectively, in 2 h in simulated gastric fluid (SGF). The majority of the drug load (90%) was released in 5 and 7 h from hydrated and dried microspheres, respectively, in simulated intestinal fluid (SIF). Prior incubation of hydrated microspheres (cross-linked using 0.5 M CaCl(2)) in SGF prolonged the time of release in SIF to 10 h, which has implications for the design of protocols and correlation with in vivo release behaviour. Restricted propranolol release in SGF and complete extraction in SIF demonstrate the potential of alginate gel microspheres for oral delivery of pharmaceuticals.

In vitro evaluation of chitosan coated- and uncoated-calcium alginate beads containing methyl salicylate-lactose physical mixture

CONTEXT

Methyl salicylate-lactose physical mixture (1:1 and 1:1.5 ratios) was incorporated into calcium alginate beads by a coacervation method involving an ionotropic gelation/polyelectrolyte complexation approach.

OBJECTIVES

This study aims to determine the influence of chitosan coating over the beads on drug entrapment efficiency (DEE) and release characteristics in artificial saliva compared to that of the uncoated beads.

RESULTS AND DISCUSSION

Changes in formulation parameters (gelation time, concentrations of Ca(2+) and alginate) resulted in decrease in DEE of chitosan-uncoated beads (p < 0.05). This is due to the combined effects of drug leach-out from the physical mixture by Ca(2+) ions, alginate gel matrix cross-linking and free drug diffusion from chitosan-uncoated beads. However, an increment in the DEE was seen for chitosan-coated beads. A rapid drug release profile was noted for uncoated beads, but for chitosan-coated beads a sustained release profile was depicted depending upon the coating conditions. Chitosan-coated beads had reduced swelling and erosion properties and thus behaved as a physical barrier to drug release. Shifting from anomalous transport type to Fickian transport confirmed the formation of physical barrier onto chitosan-coated beads.

CONCLUSION

Calcium alginate beads could be used as a controlled-release system for methyl salicylate-lactose physical mixture.

Development and evaluation of calcium alginate beads prepared by sequential and simultaneous methods

The objective of this study was to develop a sustained release dosage form of Trimetazidine dihydrochloride (TMZ) using a natural polymeric carrier prepared in a completely aqueous environment. TMZ was entrapped in calcium alginate beads prepared with sodium alginate by the ionotropic gelation method using calcium chloride as a crosslinking agent. The drug was incorporated either into preformed calcium alginate gel beads (sequential method) or incorporated simultaneously during the gelation stage (simultaneous method). The beads were evaluated for particle size and surface morphology using optical microscopy and SEM, respectively. Beads produced by the sequential method had higher drug entrapment. Drug entrapment in the sequential method was higher with increased CaCl2 and polymer concentration but lower with increased drug concentration. In the simultaneous method, drug entrapment was higher when polymer and drug concentration were increased and also rose to a certain extent with increase in CaCl2 concentration, where further increase resulted in lower drug loading. FTIR studies revealed that there is no interaction between drug and CaCl2. XRD studies showed that the crystalline drug changed to an amorphous state after formulation. Release characteristics of the TMZ loaded calcium alginate beads were studied in enzyme-free simulated gastric and intestinal fluid.

Adipic acid dihydrazide treated partially oxidized alginate beads for sustained oral delivery of flurbiprofen

In this study, periodate oxidation of sodium alginate was controlled such that the oxidized alginate could form isolatable beads with Ca(+2) ions. The beads of oxidized alginate having a degree of oxidation 1 mol%, entrapped 89% flurbiprofen and released almost all of its content within 1.5 h in pH 7.2 phosphate buffer solution. The beads were covalently crosslinked with adipic dihydrazide (ADH) in addition to ionic crosslinks and were characterized. Scanning electron microscopy revealed that the beads were spherical having smooth surfaces. The drug entrapment efficiency decreased (90-86%) with increasing concentration of ADH (2-6% w/v) in the gelation medium. However, the beads prolonged the drug release in alkaline dissolution medium up to 8 h depending upon the concentration of ADH. The beads prepared with 2% ADH swelled more rapidly and led to faster drug release in either pH 1.2 HCl solution or pH 7.2 phosphate buffer solution. The swelling tendencies were reduced and the drug release became slower with higher concentrations in either fluid. The drug diffusion from the beads followed super case II transport mechanism. FTIR spectroscopy indicated stable nature of flurbiprofen in the beads and therefore had potential as sustained oral delivery system for the drug.

Preliminary investigation on the development of diltiazem resin complex loaded carboxymethyl xanthan beads

The objective of this study was to develop a multiunit sustained release dosage form of diltiazem using a natural polymer from a completely aqueous environment. Diltiazem was complexed with resin and the resinate-loaded carboxymethyl xanthan (RCMX) beads were prepared by interacting sodium carboxymethyl xanthan (SCMX), a derivatized xanthan gum, with Al(+3) ions. The beads were evaluated for drug entrapment efficiency (DEE) and release characteristics in enzyme free simulated gastric fluid (SGF, HCl solution, pH 1.2) and simulated intestinal fluid (SIF, USP phosphate buffer solution, pH 6.8). Increase in gelation time from 5 to 20 min and AlCl(3) concentration from 1 to 3% decreased the DEE respectively from 95 to 79% and 88.5 to 84.6%. However, increase in gum concentration from 1.5 to 2.5% increased the DEE from 86.5 to 90.7%. The variation in DEE was related to displacement of drug from the resinate by the gel forming Al(+3) ions. While 75-82% drug was released in 2 h in SGF from various beads, 75 to 98% drug was released in 5 hour in SIF indicating the dependence of drug release on pH of dissolution media. Although the beads maintained their initial integrity throughout the dissolution process in both media, as evident from scanning electron microscopic studies, the faster release in SGF was accounted for higher swelling of the beads in SGF than in SIF. When release data (up to 60%) was fitted in power law expression, the drug release was found to be controlled by diffusion with simultaneous relaxation phenomena.

Preparation, in vitro and in vivo evaluation of stomach-specific metronidazole-loaded alginate beads as local anti-Helicobacter pylori therapy

Metronidazole (MZ), a common antibacterial drug used in treatment of H. pylori, was prepared in chitosan-treated alginate beads by the ionotropic gelation method. A (3x2x2) factorially designed experiment was used in which 3 viscosity-imparting polymers namely, methyl cellulose, carbopol 934P and kappa-carrageenan, 2 concentrations (0.2 and 0.4% w/v) of chitosan as encapsulating polymer and 2 concentrations (2.5 and 5% w/w) of the low density magnesium stearate as a floating aid were tested. The drug entrapment efficiency (%), the percent of floating beads and the time for 80% of the drug to be released (T(80%)) were the responses evaluated. The bead formula containing 0.5% kappa-carrageenan, 0.4% chitosan and 5% magnesium stearate showed immediate buoyancy, optimum drug entrapment efficiency and extended drug release. The histopathological examination of mice stomachs and in vivo H. pylori clearance tests were carried out by orally administering MZ floating alginate beads or MZ suspension, to H. pylori infected mice under fed conditions as a single daily dose for 3 successive days in different doses 5, 10, 15 and 20 mg/kg. The histopathological examination showed that groups receiving MZ in the form of floating alginate beads at doses 10, 15 and 20 mg/kg were better than the corresponding suspension form, regarding eradication of H. pylori infection. The in vivo H. pylori clearance tests showed that MZ floating beads with a dose of 15 mg/kg provided 100% clearance rate whereas the MZ suspension with a dose of 20 mg/kg gave only 33.33%.

The effect of drug concentration and curing time on processing and properties of calcium alginate beads containing metronidazole by response surface methodology

The purpose of present research work was to prepare calcium alginate beads containing water-soluble drug metronidazole using 3(2) factorial design, with drug concentration and curing time as variables. Curing time was kept as low as possible to improve entrapment with increasing drug concentration. Mostly the drugs which had been encapsulated were water insoluble to facilitate drug encapsulation; a characteristic drug release as whole process is aqueous based. Entrapment efficiency was in the range of 81% to 96% wt/wt, which decreased with decrease in polymer concentration and increase in curing time. The beads were spherical with size range between 1.4 and 1.9 mm. Scanning electron microscope (SEM) photomicrographs revealed increase in the leaching of drug crystals with increased curing time and high drug concentrations. In acidic environment, the swelling ratio was 200% in 30 minutes, but in basic medium, it increased to a maximum of 1400% within 120 minutes. In acidic medium, the swelling and drug release properties were influenced by drug solubility, whereas in phosphate buffer these properties were governed by the gelling of polymer and exhibited curvilinear and quadratic functions of both the variables, respectively.

Entrapment efficiency and release characteristics of polyethyleneimine-treated or -untreated calcium alginate beads loaded with propranolol–resin complex

Propranolol-HCl-loaded calcium alginate (ALG) beads, propranolol-resin complex (resinate)-loaded calcium alginate (RALG) beads and polyethyleneimine (PEI)-treated RALG (RALG-PEI) beads were prepared by ionotropic gelation/polyelectrolyte complexation method. The beads were evaluated and compared in respect of drug entrapment efficiency (DEE) and release characteristics in simulated gastric fluid (SGF, 0.1(N) HCl, pH 1.2) and simulated intestinal fluid (SIF, phosphate buffer, pH 6.8). DEE of RALG beads was considerably higher than that of ALG beads containing unresinated drug. However, DEE of RALG beads decreased with increase in both gelation time and concentration of the gel forming Ca2+ ions due to drug displacement from resinate. PEI treatment of RALG beads further decreased DEE as the polycation also displaced the drug from the resinate. The release of drug from all the beads was slow and incomplete in SGF owing to considerably less swelling of the beads and the decrease in drug release from the beads followed the order: RALG-PEI<RALG<ALG. In contrast to rapid discharge of the drug by ALG beads in SIF, RALG beads provided marginal prolongation in drug release as both ALG and RALG beads swelled and eroded rapidly although at different rates. On the other hand, drug release from RALG-PEI beads in SIF was considerably prolonged for different periods of time depending upon the conditions of PEI treatment. Interaction of the polycation with alginate resulted in the formation of polyelectrolyte complex membrane as evident from scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and fourier-transform infrared spectroscopy (FTIR) studies. The membrane having reduced swelling and erosion properties behaved as a physical barrier to drug release. Kinetics of the drug release also confirmed the formation of physical barrier as anomalous transport type of release associated with. RALG beads tended to shift towards Fickian transport in case of RALG-PEI beads.

In situ cross-linking of sodium alginate with calcium and aluminum ions to sustain the release of theophylline from polymeric matrices

Small matrices of calcium alginate or aluminium alginate have been investigated as possible controlled release systems for drugs. The objective of the present study was to sustain the release of theophylline from alginate matrices using different concentrations of aluminium chloride and calcium chloride in presence and absence of HPMC. Tablets containing differing concentrations of aluminium and calcium chloride were produced and the release rate of theophylline was tested using the basket dissolution apparatus over 8 h. Increasing amounts of aluminium chloride from 0.0001 to 0.00068 moles decreased the release of theophylline from 95.1 +/- 0.27 to 29.5 +/- 1.5, indicating a significant effect of aluminium ions on a reduction in the release rate of theophylline from sodium alginate matrices. In the case of matrices containing different concentrations of calcium ions, as the concentration of calcium chloride increased, the release rate increased to an optimum then declined after this. This was due to insufficient calcium ions being available to cross-link with the sodium alginate to form an insoluble gel. The effect of aluminium ions, as this is a trivalent ion compared to calcium, which is a divalent ion, aluminium ions are able to decrease the release rate with a smaller concentration compared to calcium ions. The results also showed that the presence of HPMC caused a reduction in release rate of theophylline from alginate matrices containing calcium chloride. Whereas, in the case of alginate matrices containing aluminium chloride the release rate of theophylline increased in presence of HPMC. For comparing the dissolution data, dissolution efficiency (DE) was used. The values of DE are consistent with the dissolution data. The results show that within a formulation series, DE values generally decrease when the cation concentration increases and this criterion can be used to describe the effect of calcium and aluminium ions on the release behaviour of theophylline from polymeric matrices.

Effect of the formulation on the in-vitro release of propranolol from gellan beads

Gellan gum beads of propranolol hydrochloride, a hydrophilic model drug, were prepared by solubilising the drug in a dispersion of gellan gum and then dropping the dispersion into calcium chloride solution. The droplets formed gelled beads instantaneously by ionotropic gelation. Major formulation and process variables which might influence the preparation of the beads and the drug release from gellan gum beads were studied. Very high entrapment efficiencies were obtained (92%) after modifying the pH of both the gellan gum dispersion and the calcium chloride solution. The beads could be stored for 3 weeks in a wet or dried state without modification of the drug release. Oven-dried beads released the drug somewhat more slowly than the wet or freeze-dried beads. The drug release from oven-dried beads was slightly affected by the pH of the dissolution medium. Gellan gum could be a useful carrier for the encapsulation of fragile drugs and provides new opportunities in the field of bioencapsulation.