Compatibility studies between mannitol and omeprazole sodium isomers.

Area of Science:

• Pharmaceutical Science
• Drug Delivery Systems
• Physical Chemistry

Background:

• Omeprazole, a proton pump inhibitor, degrades in acidic conditions, leading to variable patient bioavailability.
• Excipients can interact with active pharmaceutical ingredients, altering drug bioavailability.
• S-omeprazole offers more predictable bioavailability compared to racemic omeprazole.

Purpose of the Study:

• To investigate the compatibility between omeprazole sodium isomers (R- and S-omeprazole sodium) and mannitol, a common excipient.
• To understand how these interactions influence drug properties and potentially bioavailability.

Main Methods:

• Differential Scanning Calorimetry (DSC) for bulk drug analysis.
• Attenuated Total Reflectance (ATR) Infrared (IR) spectroscopy for powder mixtures.
• Localized Thermal Analysis (LTA) for drug disks.

Main Results:

• DSC indicated interaction between R-omeprazole sodium and mannitol, evidenced by decreased melting points and peak broadening.
• DSC of S-omeprazole sodium did not show a distinct melting temperature, despite the drug being crystalline.
• ATR-IR revealed differences in interactions: R-omeprazole sodium showed both amino (N-H) and imino (N-H) stretching frequencies with mannitol, while S-omeprazole sodium showed only N-H stretching.

Conclusions:

• Different tautomeric forms of S- and R-omeprazole sodium lead to variations in crystallinity.
• These variations are responsible for the observed interactions with mannitol.
• The interactions between omeprazole sodium isomers and mannitol may directly correlate with differences in bioavailability.