|dc.description.abstract||Clarithromycin is a 14-membered-ring , macrolide antibiotic, a derivative of
erythromycin, that is commonly used for the treatment of chronic, obstructive upper -
and lower respiratory -, skin - and soft tissue -, as well as for gastric (duodenal ulcers
caused by H. pylon] infections.
During this study, polymorphic and pseudopolymorphic forms were evaluated,
identified and characterised, using normal spectral and thermal methods, such as x-ray
powder diffractometry, infrared spectroscopy, differential scanning calorimetry,
thermogravimetrical analysis and thermal microscopy.
Literature described Form 0, a solvate; Form I, a metastable polymorph; Form II, the
thermodynamically more stable polymorph; Form Ill, a solvate (from acetonitrile) and
Form IV, an amorph.
Various solvents were used for slow recrystallisation of clarithromycin. The
thermodynamically more stable Form II was prepared from acetone, methanol,
benzene, dimethylformamide and tetrahydrofuran. Recrystallisations from acetonitrile
produced Form II, and not Form Ill as reported in the literature. Two new forms, i.e.
an ethyl acetate (Form V) and a chloroform solvate (Form VI) were prepared.
Recrystallisation from both ethanol and iso-propanol produced Forms 0 and II.
Although Form 0 desolvated prior to analysis, thus no longer contained the
recrystallisation solvent, these crystals retained the structure of the solvated Form 0.
Form 0 was recrystallised from n-propanol, n-butanol, dioxane and dichloromethane.
Forms 0, 1, Ill, V and VI all transformed into the thermodynamically more stable Form
II, after storage at room conditions.
The dissolution results, relating to chloroform recrystallisation, showed that
desolvation can improve the dissolution rate, since the chloroform solvate had a poor
dissolution performance (61% after 30 minutes), whilst the desolvated form was
almost completely dissolved within 30 minutes (96%), in the 0.1 M sodium acetate