Study of Different Crystalline forms of Mannitol: Comparative Behaviour under Compression

Abstract

Mannitol is an exclpient commonly used in pharmaceutical formulation. Several polymorphic forms have been described but there are only few reports in past literature about their crystalline structures and about their differential properties.

The aim of this work is to prepare and to study the different polymorphic forms. An investigation of commercialized products is then carried out.

The melting points and the water contents are determined and the crystalline structure is differenciated by powder X Ray diffraction.

Four polymorphic forms have been characterized: the a form and the f3 form, which have been obtained in pure state, and the 6 form containing the a form as an impurity, and a fourth form which we have not identified at this time.

Among the commercial products, we have characterized: the g form, the a form and the unidentified form.

The compressibility of these different samples has been studied: the a form is the best. This valuable property has been found again in the commercial α product.

The particle shape seems also to have a great influence upon the compressibility properties. For the same particle size, the granulated powder has a better behaviour than native crystals powders.

Lastly, the possible polymorphic transitions under compression stress during tabletting process has been studied: no transition has been observed.