Sodium alginate and alginic acid as pharmaceutical excipients for tablet formulation: Structure-function relationship

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Polymer Chemistry

Background:

• Alginic acid and its sodium salt are widely used pharmaceutical excipients.
• Their natural origin offers advantages like safety, abundance, low cost, and biodegradability.
• However, inherent variability in these polysaccharides can hinder their use in robust tablet formulations.

Purpose of the Study:

• To review structure-property relationships of alginates concerning their technological and biopharmaceutical properties.
• To analyze compaction studies linking alginate structure to mechanical and dissolution performance.
• To discuss strategies for enhancing alginic acid as a direct compression excipient.

Main Methods:

• Compilation and analysis of existing compaction studies on alginates.
• Review of analytical methods for determining alginate chemical composition, primary structure, and molecular weight distribution.
• Synthesis of reported strategies to improve alginic acid's direct compression properties.

Main Results:

• Alginate structure significantly influences mechanical properties (compaction) and dissolution behavior.
• Variability in chemical composition and molecular weight distribution are major factors affecting direct compression.
• Specific analytical techniques are crucial for characterizing these structural parameters.

Conclusions:

• A comprehensive understanding of alginate structure is essential for developing robust solid oral dosage forms.
• Addressing alginate variability through characterization and formulation strategies can optimize their use as direct compression excipients.
• Further research into structure-property relationships will enable high-quality, consistent drug products.