Physicochemical and structural studies of triamterene

Area of Science:

• Crystallography
• Solid-state chemistry
• Pharmaceutical science

Background:

• Physicochemical techniques indicated that different crystal forms of triamterene and varying melting points do not necessarily imply polymorphism.
• Understanding the precise crystalline structure is crucial for drug formulation and stability.

Purpose of the Study:

• To elucidate the crystalline structure of triamterene.
• To investigate the presence and role of solvent molecules in the triamterene crystal lattice.
• To clarify the relationship between solvation, crystal form, and melting point.

Main Methods:

• Single-crystal X-ray diffraction analysis was employed to determine the crystal structure.
• Physicochemical characterization techniques were used to analyze different crystalline specimens.

Main Results:

• Triamterene crystallizes in a face-centered orthorhombic space group (Fdd2) from aqueous N,N-dimethylformamide solutions.
• The crystal lattice incorporates both N,N-dimethylformamide and water molecules.
• A partially occupied molecule resides on a crystallographic twofold axis within the asymmetric unit.
• Weak hydrogen bonding interactions were identified between specific atoms (O(1)-N(7), O(1)-N(5), O(2)-N(1), N(2)-N(7)).
• Solvated triamterene specimens exhibited varying melting points influenced by the presence of organic solvents and/or water.

Conclusions:

• The determined crystal structure provides definitive insight into triamterene's solid-state arrangement.
• The presence of solvent molecules and specific hydrogen bonding patterns influences the observed physical properties.
• Melting point variations in solvated triamterene are attributable to solvation, not necessarily polymorphism.