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Physical characterization of solid forms of urapidil.
S A Botha1, J K Guillory, A P Lötter
1Research Institute for Industrial Pharmacy, University of Potchefstroom for C.H.E., 2520 Potchefstroom, South Africa.
Journal of Pharmaceutical and Biomedical Analysis
|January 1, 1986
Summary
Three urapidil polymorphic forms were identified and characterized. These forms exhibit enantiotropic behavior, indicating interconversion under varying conditions, crucial for pharmaceutical development.
Area of Science:
- Pharmaceutical Chemistry
- Solid-State Chemistry
- Materials Science
Background:
- Urapidil is an antihypertensive agent.
- Understanding the polymorphic forms of active pharmaceutical ingredients (APIs) is critical for drug formulation and efficacy.
- Polymorphism can significantly impact a drug's solubility, stability, and bioavailability.
Purpose of the Study:
- To prepare and characterize different polymorphic forms of urapidil.
- To investigate the solid-state properties and stability of these urapidil polymorphs.
- To determine the thermodynamic relationship between the identified urapidil polymorphic forms.
Main Methods:
- Preparation of urapidil polymorphic forms using various techniques.
- Solid-state characterization including thermal analysis (DSC/TGA), X-ray powder diffraction (XRPD), and Infrared (IR) spectroscopy.
- Assessment of dissolution rates and solid-state stability under different conditions.
- Quantitative analysis of polymorph mixtures using solution calorimetry.
Main Results:
- Three distinct polymorphic forms of urapidil (Forms I, II, and III) were successfully prepared and identified.
- Comprehensive characterization revealed differences in their thermal behavior, diffraction patterns, IR spectra, and dissolution profiles.
- Solution calorimetry demonstrated a reproducibility of +/-3% for determining polymorph mixtures.
- Stability studies over three months indicated that urapidil Forms I, II, and III are enantiotropic.
Conclusions:
- The study successfully identified and characterized three enantiotropic polymorphic forms of urapidil.
- These findings highlight the importance of controlling polymorphism for consistent urapidil drug product performance.
- The enantiotropic nature suggests potential for interconversion, necessitating careful consideration during manufacturing and storage.