Surface electric charge of the active and inactive polymorphs of chloramphenicol palmitate

Higher zeta-potential values were found for the crystalline particles of polymorph A when compared with polymorph B of chloramphenicol palmitate when measured at identical conditions. In the case of the thermomicroscopically prepared crystal sample being a mixture of the polymorphs, the resulting zeta potential was higher than that measured for pure form B and lower than that found for form A. It has been assumed that the zeta potential reflects differences in the surface properties of the polymorphs. These differences are briefly discussed from the point of view of the adsorption of the charge-generating ions as well as of the marked differences in bioactivity reported for the polymorphs.