The Effect of Erosion and Swelling on the Dissolution of Theophylline from Low and High Viscosity Sodium Alginate Matrices

Efentakis, M.; Buckton, Graham

doi:10.1081/pdt-120002232

Cited by 50 publications

(29 citation statements)

References 14 publications

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“…However, the use of a gradient-pH system may have also provided good prediction of in vivo results. The release of PB was dependant on temperature and pH, which is in line with previous studies using SA-drug formulations (34,35). As shown in Fig.…”

Section: Drug Release Studies and In Vitro Dissolutionsupporting

confidence: 77%

Probucol Release from Novel Multicompartmental Microcapsules for the Oral Targeted Delivery in Type 2 Diabetes

et al. 2014

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Abstract. In previous studies, we developed and characterised multicompartmental microcapsules as a platform for the targeted oral delivery of lipophilic drugs in type 2 diabetes (T2D). We also designed a new microencapsulated formulation of probucol-sodium alginate (PB-SA), with good structural properties and excipient compatibility. The aim of this study was to examine the stability and pH-dependent targeted release of the microcapsules at various pH values and different temperatures. Microencapsulation was carried out using a Büchi-based microencapsulating system developed in our laboratory. Using SA polymer, two formulations were prepared: empty SA microcapsules (SA, control) and loaded SA microcapsules (PB-SA, test), at a constant ratio (1:30), respectively. Microcapsules were examined for drug content, zeta potential, size, morphology and swelling characteristics and PB release characteristics at pH 1.5, 3, 6 and 7.8. The production yield and microencapsulation efficiency were also determined. PB-SA microcapsules had 2.6±0.25% PB content, and zeta potential of −66±1.6%, suggesting good stability. They showed spherical and uniform morphology and significantly higher swelling at pH 7.8 at both 25 and 37°C (p<0.05). The microcapsules showed multiphasic release properties at pH 7.8. The production yield and microencapsulation efficiency were high (85±5 and 92±2%, respectively). The PB-SA microcapsules exhibited distal gastrointestinal tract targeted delivery with a multiphasic release pattern and with good stability and uniformity. However, the release of PB from the microcapsules was not controlled, suggesting uneven distribution of the drug within the microcapsules.

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Section: Drug Release Studies and In Vitro Dissolutionsupporting

confidence: 77%

Probucol Release from Novel Multicompartmental Microcapsules for the Oral Targeted Delivery in Type 2 Diabetes

et al. 2014

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“…The lower rehydration of beads that were prepared at shorter curing time may be correlated to the incomplete cross-linking of the sodium alginate. 9,14,15 When MZ-loaded Ca-alginate beads were evaluated for drug release in 0.1 N HCl, pH 1.2 (Figure 7), 70% to 90% release of drug from the beads occurred within 20 to 30 minutes, which was in accordance with Murata et al, 13 Multiple regression data revealed retarding effect of curing time on drug release, which might be caused by slower penetration of medium in highly cross-linked beads, but the overall drug release was governed by solubility of drug in dissolution medium and not by swelling properties of beads.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, during ionotropic gelation, curing time can be a crucial factor in governing the entrapment efficiency. [1][2][3][4][5][6][7][11][12][13][14] Metronidazole (MZ) was selected as a model drug for incorporation in calcium alginate beads. With drug concentration and curing time as variables, 3 2 factorial design was applied.…”

Section: +mentioning

confidence: 99%

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

2006

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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.

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“…The controlled-release of drug substances from sodium alginate matrices would be expected to correlate with the swelling and erosion of the polymer (8,9). The alginate concentrations in the gel and diffusion layers around the polymer matrix could be expected to range from very high values at the boundary with the unhydrated alginate to relatively dilute concentrations at the boundary with the bulk alginate solution.…”

Section: Concentration Effect On Viscoelasticitymentioning

confidence: 99%

“…Current pharmacopeial specifications (USP-NF) for sodium alginate do not enable the characterization of variations in the molecular weight distribution and/or chemical composition of sodium alginate. Since these variations can markedly affect the processability or performance of a sodium alginate-containing pharmaceutical product (8,9), adherence to the USP-NF monograph may not ensure the interchangeability of sodium alginates from different sources or even various batches from the same manufacturer. Previous studies have shown that the inter-manufacturer and/or inter-batch (lot) variability of excipients can exert a significant effect on the performance of the final formulations, even though these excipients meet the pharmacopeial specifications (10)(11)(12)(13)(14).…”

Section: Introductionmentioning

confidence: 99%

Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

et al. 2010

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Abstract. Polymeric excipients are often the least well-characterized components of pharmaceutical formulations. The aim of this study was to facilitate the QbD approach to pharmaceutical manufacturing by evaluating the inter-grade and inter-batch variability of pharmaceutical-grade polymeric excipients. Sodium alginate, a widely used polymeric excipient, was selected for evaluation using appropriate rheological methods and test conditions. The materials used were six different grades of sodium alginate and an additional ten batches of one of the grades. To compare the six grades, steady shear measurements were conducted on solutions at 1%, 2%, and 3% w/w, consistent with their use as thickening agents. Small-amplitude oscillation (SAO) measurements were conducted on sodium alginate solutions at higher concentrations (4-12% w/w) corresponding to their use in controlled-release matrices. In order to compare the ten batches of one grade, steady shear and SAO measurements were performed on their solutions at 2% w/w and 8% w/w, respectively. Results show that the potential interchangeability of these different grades used as thickening agents could be established by comparing the apparent viscosities of their solutions as a function of both alginate concentration and shear conditions. For sodium alginate used in controlled-release formulations, both steady shear behavior of solutions at low concentrations and viscoelastic properties at higher concentrations should be considered. Furthermore, among batches of the same grade, significant differences in rheological properties were observed, especially at higher solution concentrations. In conclusion, inter-grade and inter-batch variability of sodium alginate can be determined using steady shear and small-amplitude oscillation methods.

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The Effect of Erosion and Swelling on the Dissolution of Theophylline from Low and High Viscosity Sodium Alginate Matrices

Cited by 50 publications

References 14 publications

Probucol Release from Novel Multicompartmental Microcapsules for the Oral Targeted Delivery in Type 2 Diabetes

Probucol Release from Novel Multicompartmental Microcapsules for the Oral Targeted Delivery in Type 2 Diabetes

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

Rheological Evaluation of Inter-grade and Inter-batch Variability of Sodium Alginate

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