Compatibility of the antitumoral β-lapachone with different solid dosage forms excipients

The objective of the present study was to evaluate the compatibility of the β-lapachone (βLAP), an antitumoral drug in clinical phase, with pharmaceutical excipients of common use including diluents, binders, disintegrants, lubricants and solubilising agents. Differential scanning calorimetry (DSC) was used for a first screening to find small variations in peak temperatures and/or their associated enthalpy for six drug/excipient combinations (magnesium stearate, sodium estearyl fumarate, dicalcium phosphate dihydrate, mannitol, randomized methyl-β-cyclodextrin and hydroxypropyl-β-cyclodextrin), which indicate some degree of interaction.Additional studies using Fourier transformed infrared spectroscopy (FTIR), optical microscopy (OM) and heating–cooling DSC (HC-DSC) confirmed the incompatibility of βLAP with magnesium stearate and dicalcium phosphate dihydrate. Those excipients should be avoided in the development of solid dosage forms.