Polymorphism and solvates of flecainide base

Abstract

Flecainide base is pharmaceutically active substance used for production of flecainide acetate which is known in market as Tambacor, Almarytm, Apocard, Ecrinal or Flecaine. It is determined that flecainide base forms four polymorphic forms abbreviated as I_b, II_b, III_b and IV_b. Flecainide base form I_b is thermodynamically stable form at laboratory temperature while form III_b is stable at higher temperatures. Flecainide form I_b absorbs water in its structure between layers and forms non-stoichiometric hydrate. Flecainide base binds with organic solvents and form monosolvates. Flecainide base form I_b crystallizes in orthorhombic crystals with lattice parameters a = 27.88 Å, b = 13.78 Å, c = 9.98 Å and two independent molecules in unit cell (Z′ = 2; Z = 8). Molecule arrangement in flecainide base form I_b structure is not dense and it forms a channel-type structure, where molecules of water and alcohols are placed.

• Alcohol solvates
• crystalline forms
• flecainide
• thermal analysis
• X-ray diffraction