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AAPS PharmSciTech. 2000 June; 1(2): 72–79.
Published online 2015 February 19. doi:  10.1208/pt010215
PMCID: PMC2784826

Factorial analysis of the influence of dissolution medium on drug release from carrageenan-diltiazem complexes


This research studied the influence of buffer composition, pH, and ionic strength on the release of diltiazem hydrochloride from a complex of the drug with lambda carrageenan. Two viscosity grades of carrageenan were also compared. A factorial analysis was used to evaluate the influence of individual variables and their interactions. Both the complex solubility, measured as the drug concentration in equilibrium with the solid complex, and the drug release rate from constant surface area were considered. The increase of ionic strength significantly increased complex solubility in all the buffer systems. A significant effect of polymer grade on complex solubility was evidenced only in phosphate buffer with a pH of 6.8, indicating lower solubility of the complex when higher polymer molecular weight was involved. In most cases, drug release rate decreased when high polymer grade was involved in the complex. Ionic strength did not always have a significant effect on drug release rate and was quantitatively less important than for solubility lonic strength especially affected the drug release profiles. At higher ionic strength drug release was no longer constant, but decreased with time, probably because of lower polymer solubility.

Keywords: lambda carrageenan, 4rug-polymer complex, 4iltiazem HCl, 4issolution medium pH and ionic strength, Factorial analysis

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Selected References

These references are in PubMed. This may not be the complete list of references from this article.
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