Development of directly compressible metformin hydrochloride by the spray-drying technique.

Metformin hydrochloride exhibits poor compressibility during compaction, often resulting in weak and unacceptable tablets with a high tendency to cap. The purpose of this study was to develop directly compressible metformin hydrochloride by the spray-drying technique in the presence of polymer. Metformin hydrochloride was dissolved in solutions containing a polymer, namely polyvinylpyrrolidone (PVP K30), in various concentrations ranging from 0-3% (m/V). These solutions were employed for spray-drying. Spray-dried drug was evaluated for yield, flow property and compressibility profile. Metformin hydrochloride spray-dried in the presence of 2% PVP K30 showed an excellent flow property and compressibility profile. From the calculated Heckel's parameter (Py = 2.086), it was demonstrated that the treated drug showed better particle arrangement in the initial compression stage. Kawakita analysis revealed better packability of the treated drug compared to the untreated drug. Differential scanning calorimetry and Fourier transform infrared spectroscopy experiments showed that the spray-dried drug did not undergo any chemical modifications. Tablets made from the spray-dried drug (90%, m/m) were evaluated for crushing strength, friability and disintegration time and the results were found satisfactory.