The application of microwave formulation and isothermal titration calorimetry for pharmaceutical compounds

Solid dispersions are commonly used to overcome bioavailability issues of poorly water soluble drugs. Various preparation methods along with carrier systems have been used to develop solid dispersions. However, this study investigates the application of microwave heating methods in formulation development alongside associated analytical investigations.

Formulations of poorly soluble drugs, namely, fenofibrate, gemfibrozil, ibuprofen, ibuprofen (+) S and phenylbutazone were prepared using a microwave technique and compared with standard formulation techniques. Mesoporous silicas and polyethylene glycol were used as excipients. Then in vitro dissolution analysis was carried out for the performance evaluation of the resultant formulations. It was found that effective products were produced as a result of microwave processing compared with the traditional techniques. Analytical techniques such as differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy ((FTIR) were employed to determine the solid state properties, i.e. thermal stability, crystalline state, physical appearance and chemical stability of developed formulations. The overall findings indicate that successful formulation can be achieved using microwave heating.

Isothermal titration calorimetry (ITC) was used to probe the interactions of model drugs, namely, caffeine, diprophylline, etofylline, paracetamol and theophylline with excipients such as sodium dodecyl sulphate (SDS), sodium deoxycholate (NaDC) and PEG. Thermodynamic data suggests the successful use of ITC to investigate drug-excipient interactions. In summary, the potential of microwave heating in formulation development and ITC to characterise drug-excipient interactions was thoroughly investigated and both found as potential alternatives to more traditional techniques.