Resumen:
Terbinafine (TB) is an allylamine derivative used as oral and topical antifungal agent. The physicochemical properties of the complexes between TB and different cyclodextrins (CDs): alpha-CD, beta-CD, hydroxypropyl beta-CD, methyl beta-CD and gamma-CD, have been studied in pH 12 aqueous solutions at 25 A degrees C and in the solid state. Different phase solubility profiles of TB in the presence of CDs have been obtained: A(L) type for TB with hydroxypropyl beta-CD and gamma-CD, A(P) type for the complexes with methyl beta-CD and alpha-CD, while a B(S) profile was found for TB-beta-CD. The apparent stability constants of the complexes were calculated at 25 A degrees C from the phase solubility diagrams. The higher increase of TB solubility, up to 200-fold, together with the higher value of the stability constant were found for the complex with methyl beta-CD. Solid systems of 1:1 drug:CD molar ratio were prepared and characterised using X-ray diffraction patterns, thermal analysis and FTIR spectroscopy. The coevaporation method can be considered the best method in preparing these solid complexes. The complexes of TB with natural CDs, except with alpha-CD, were crystalline, whereas the methyl and hydroxypropyl derivatives gave rise to amorphous phases. Dissolution rate studies have been performed with TB-beta-CD and TB-HP beta-CD complexes, showing a positive influence of complexation on the drug dissolution.