THERMAL-ANALYSIS AS A SCREENING TECHNIQUE IN PREFORMULATION STUDIES OF PICOTAMIDE SOLID DOSAGE FORMS

The potential compatibilities of several commonly used pharmaceutical excipients with picotamide were evaluated using differential scanning calorimetry (DSC). The effects of aging and of mechanical treatment (b lending, grinding, or kneading) of samples were also evaluated. Hot-st age microscopy (HSM) and scanning electron microscopy (SEM) were used as complementary techniques to implement and assist in interpretation of the DSC results. DSC analysis evidenced a noticeable modification o f drug thermal features in the mixtures with palmitic acid, stearic ac id, stearyl alcohol, polyethylene glycol (PEG) 20,000 and sorbitol, bu t HSM analysis showed that the DSC behavior was mainly because of the drug dissolution in the melted excipient, which allowed the presence o f important solid-solid interactions to be excluded. Compatibility wit h Mg stearate was also found, even if sample manipulation induced the partial conversion of Mg stearate in a pseudopolymorphic modification. Mechanical stress displayed an increased hygroscopicity of mixtures w ith glucose and lactose, as well as some solid-solid interactions with lactose and mannitol.