Captopril (CAP) was the first commercially available angiotensine-converting enzyme (ACE) inhibitor. In the anti-hypertensive
therapy is considered the selected drug has to be therapeutically effective together with reduced toxicity. CAP is an antihypertensive
drug currently being administered in tablet form. In order to investigate the possible interactions between CAP and excipients
in tablets formulations, differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis completed by X-ray powder
diffraction (XRPD) and Fourier transform infrared spectroscopy (FTIR) were used for compatibility studies. A possible drug-excipient
interaction was observed with magnesium stearate by DSC technique.