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Oleate salt formation and mesomorphic behavior in the propranolol/oleic acid binary system
K J Crowley1, R T Forbes, P York
1Drug Delivery Group, Postgraduate Studies in Pharmaceutical Technology, The School of Pharmacy, University of Bradford, Bradford, BD7 1DP, UK.
Journal of Pharmaceutical Sciences
|June 3, 1999
Summary
Propranolol and oleic acid form a complex, propranolol oleate, with unique mesophase properties. This drug salt formation impacts pharmaceutical systems, influencing drug behavior and formulation.
Area of Science:
- Physical Chemistry
- Materials Science
- Pharmaceutical Sciences
Background:
- Drug-excipient interactions are crucial for pharmaceutical formulation.
- Fatty acid salts of drugs can exhibit unique physical properties.
- Understanding phase behavior is key to predicting drug stability and performance.
Purpose of the Study:
- To investigate the binary system of propranolol and oleic acid.
- To characterize the interactions and complex formation between propranolol and oleic acid.
- To explore the mesophase behavior of the resulting propranolol oleate complex.
Main Methods:
- Thermal analysis (Differential Scanning Calorimetry, Thermogravimetric Analysis) for phase diagram construction.
- Infrared spectroscopy for chemical interaction confirmation.
- X-ray powder diffractometry (wide-angle and small-angle) for structural and mesophase analysis.
Main Results:
- A binary phase diagram was constructed, revealing complex formation at equimolar composition.
- The equimolar complex, propranolol oleate, was identified and confirmed via spectroscopy.
- Propranolol oleate exhibited mesophase behavior with distinct long-range order (25 Å d-spacing) across three identified phases.
Conclusions:
- Drug-fatty acid salt formation, specifically propranolol oleate, is feasible and leads to unique mesomorphic properties.
- The identified mesophase behavior of propranolol oleate influences its physical characteristics, such as its unctuous nature.
- Mesomorphism in pharmaceutical systems has significant implications for drug formulation, stability, and delivery.