Search tips
Search criteria 


Logo of aapspharmspringer.comThis journalToc AlertsSubmit OnlineOpen Choice
AAPS PharmSciTech. 2007 September; 8(3): E158–E165.
Published online 2007 September 7. doi:  10.1208/pt0803072
PMCID: PMC2750568

Sodium alginate-magnesium aluminum silicate composite gels: Characterization of flow behavior, microviscosity, and drug diffusivity


The aims of the present study were to characterize the flow behavior and thixotropic properties of sodium alginate-magnesium aluminum silicate (SA-MAS) composite gels with various ratios of SA and MAS, and to investigate the drug diffusivity and microviscosity of the composite gels. Moreover, interaction of SA and MAS in the form of dry composite was examined by using Fourier Transform Infrared (FTIR), and a possible structure model of SA-MAS composite gel was illustrated. Incorporating MAS into the SA gels provided higher viscosity and changed the flow behavior from Newtonian to pseudoplastic with thixotropy. This was due to the formation of electrostatic force and inter-molecular hydrogen bonding between SA and MAS, leading to a denser matrix structure of the composite gels. Increasing the content of MAS decreased the drug diffusivity but increased the microviscosity of the composite gels. The denser matrix structure of the composite gels had a higher tortuosity, resulting in slower drug diffusion through water-filled channels in the gels. This finding suggested that incorporating MAS into the SA gels could improve the flow behavior and sustain drug release from the gels because of the formation of a matrix structure between SA and MAS in the gels.

Full Text

The Full Text of this article is available as a PDF (589K).

Selected References

These references are in PubMed. This may not be the complete list of references from this article.
1. Zatz JL, Kushla GP. Gels. In: Lieberman HA, Rieger MM, Banker GS, editors. Pharmaceutical Dosage Forms: Disperse Systems. New York, NY: Marcel Dekker; 1989. pp. 495–510.
2. Alexandre M, Dubois P. Polymer-layered silicate nanocomposites: preparation, properties and uses of a new class of materials. Mater Sci Eng R. 2000;28:1–63. doi: 10.1016/S0927-796X(00)00012-7. [Cross Ref]
3. Murray HH. Traditional and new application for kaolin, smectite, and palygorskite: a general overview. Appl Clay Sci. 2000;17:207–221. doi: 10.1016/S0169-1317(00)00016-8. [Cross Ref]
4. Ciullo PA. Rheological properties of magnesium aluminum silicate/xanthan gum dispersions. J Soc Cosmet Chem. 1981;32:275–285.
5. Ciullo PA, Braun DB. Clay/carbomer mixtures enhance emulsion stability. Cosmet Toiletries Mag. 1991;106:89–95.
6. Kibbe HA. Handbook of Pharmaceutical Excipients. Washington, DC: American Pharmaceutical Association; 2000. pp. 465–467.
7. Draget KI. Alginates. In: Philips GO, Williams PA, editors. Handbook of Hydrocolloids. Cambridge, MA: Woodhead; 2000. pp. 379–395.
8. González-Rodríguez ML, Holgado MA, Sánchez-Lafuente C, Rabasco AM, Fini A. Alginate/chitosan particulate systems for sodium diclofenac release. Int J Pharm. 2002;232:225–234. doi: 10.1016/S0378-5173(01)00915-2. [PubMed] [Cross Ref]
9. Murata Y, Miyamoto E, Kawashima S. Additive effect of chondroitin sulfate and chitosan on drug release from calcium-induced alginate gel beads. J Control Release. 2007;38:101–108. doi: 10.1016/0168-3659(95)00098-4. [Cross Ref]
10. Wang K, He Z. Alginate-konjac glucomannan-chitosan beads as controlled release matrix. Int J Pharm. 2002;244:117–126. doi: 10.1016/S0378-5173(02)00324-1. [PubMed] [Cross Ref]
11. Puttipipatkhachorn S, Pongjanyakul T, Priprem A. Molecular interaction in alginate beads reinforced with sodium starch glycolate or magnesium aluminum silicate, and their physical characteristics. Int J Pharm. 2005;293:51–62. doi: 10.1016/j.ijpharm.2004.12.006. [PubMed] [Cross Ref]
12. Pongjanyakul T, Priprem A, Puttipipatkhachorn S. Influence of magnesium aluminium silicate on rheological, release and permeation characteristics of diclofenac sodium aqueous gels in-vitro. J Pharm Pharmacol. 2005;57:429–434. doi: 10.1211/0022357055795. [PubMed] [Cross Ref]
13. Lemoine D, Wauters F, Bouchend'homme S, Préat V. Preparation and characterization of alginate microspheres containing a model antigen. Int J Pharm. 1998;176:9–19. doi: 10.1016/S0378-5173(98)00303-2. [Cross Ref]
14. Martin A. Physical Pharmacy. Philadelphia, PA: Lea & Febiger; 1993. pp. 393–422.
15. Higuchi WI. Analysis of data on the medicament release from ointments. J Pharm Sci. 1962;51:802–804. doi: 10.1002/jps.2600510825. [PubMed] [Cross Ref]
16. Maitani Y, Kugo M, Nakagaki M, Nagai T. Ionic size and behavior of diclofenac salts in water and ethanol/water mixtures by conducivity at 25°C. J Pharm Sci. 1993;82:1245–1249. doi: 10.1002/jps.2600821212. [PubMed] [Cross Ref]
17. Sartori C, Finch DS, Ralph B. Determination of the cation content of alginate thin films by FTIR spectroscopy. Polym. 1997;38:43–51. doi: 10.1016/S0032-3861(96)00458-2. [Cross Ref]
18. Pongjanyakul T, Priprem A, Puttipipatkhachorn S. Investigation of novel alginate-magnesium aluminum silicate microscoposite filsm for modified-release tablets. J Control Release. 2005;107:343–356. doi: 10.1016/j.jconrel.2005.07.003. [PubMed] [Cross Ref]
19. Gupta MK, Vanwert A, Bogner RH. Formation of physically stable amorphous drugs by milling with Neusilin. J Pharm Sci. 2003;92:536–551. doi: 10.1002/jps.10308. [PubMed] [Cross Ref]
20. Lin-Gibson S, Kim H, Schmidt G, Han CC, Hobbie EK. Shear-induced structure in polymer-clay nanocomposite solutions. J Colloid Interface Sci. 2004;274:515–525. doi: 10.1016/j.jcis.2004.03.039. [PubMed] [Cross Ref]
21. Gilbert JC, Hadgraft J, Bye A, Brookes LG. Drug release from Pluronic F-127 gels. Int J Pharm. 1986;32:223–228. doi: 10.1016/0378-5173(86)90182-1. [Cross Ref]
22. Lu G, Jun HW. Diffusion studies of methotrexate in Carbopol and Poloxamer gels. Int J Pharm. 1998;160:1–9. doi: 10.1016/S0378-5173(97)00187-7. [Cross Ref]
23. Sarisuta N, Parrott EL. Relationship of dissolution rate to viscosity of polymeric solutions. J Pharm Sci. 1982;71:1375–1380. doi: 10.1002/jps.2600711216. [PubMed] [Cross Ref]
24. Al-Khamis KI, Davis SS, Hadgraft J. Microviscosity and drug release from topical gel formulations. Pharm Res. 1986;3:214–217. doi: 10.1023/A:1016386613239. [PubMed] [Cross Ref]

Articles from AAPS PharmSciTech are provided here courtesy of American Association of Pharmaceutical Scientists