Spray-dried high-amylose sodium carboxymethyl starch: impact of α-amylase on drug-release profile

Abstract

Spray-dried high-amylose sodium carboxymethyl starch (SD HASCA) is a promising pharmaceutical excipient for sustained-release (SR) matrix tablets produced by direct compression. The presence of α-amylase in the gastrointestinal tract and the variations of the gastric residence time of non-disintegrating dosage forms may affect the presystemic metabolism of this excipient and, consequently, the drug-release profile from formulations produced with SD HASCA. In this study, the influence of α-amylase and the residence time in acidic conditions on the drug-release profile was evaluated for a once-daily acetaminophen formulation (Acetaminophen SR) and a once-daily tramadol hydrochloride formulation (Tramadol SR). Both formulations were based on SD HASCA. α-Amylase concentrations ranging from 0 IU/L to 20000 IU/L did not significantly affect the drug-release profiles of acetaminophen and tramadol hydrochloride from SD HASCA tablets (f₂>50) for all but only one of the studied conditions (f₂=47). Moreover, the drug-release properties from both SD HASCA formulations were not significantly different when the residence time in acidic medium was 1 h or 3 h. An increase in α-amylase concentration led to an increase in the importance of polymer erosion as the main mechanism of drug-release instead of drug diffusion, for both formulations and both residence times, even if release profiles remained comparable. As such, it is expected that α-amylase concentration and residence time in the stomach will not clinically affect the performance of both SD HASCA SR formulations, even if the mechanism of release itself may be affected.

Keywords:

• α-amylase
• drug delivery
• drug diffusion
• hydrophilic matrices
• in vitro drug-release
• modified starch
• polymer erosion
• spray drying
• sustained-release

Acknowledgements

This paper is dedicated to the living memory of Prof. Louis Cartilier. The authors wish to thank Prof. Leblond Chain and all the students and members of the Drug Formulation and Analysis Research Axis for proofreading this paper and for the helpful suggestions. The authors acknowledge the contributions of Mr. Martin Jutras for method validation experiments and Dr. Fabien Brouillet for the scanning electron microscope picture of SD HASCA reported in this manuscript.

Disclosure statement

The authors report no declarations of interest. The authors alone are responsible for the content and writing of this article. This work was supported by the scholarship of Fundação para a Ciência e a Tecnologia (Portugal) [grant number: SFRH/BD/23197/2005].