Biocompatible inter polymer complex matrix tablets - an oral sustained release Metformin formulation

Abstract

Development of sustained release formulations of Metformin hydrochloride (Met) having low bioavailability and short half-life is one of the frontier areas of research towards achieving novel drug delivery systems. Towards the same, we have prepared interpolymer complexes (IPCs) of chitosan (CH) and two different viscosity grades of hydroxypropyl methylcellulose - HPMC (K4M and K100M) in various ratios, say, 4:6, 2:8, 1:9, respectively. The IPCs are characterized by Fourier transform infrared spectroscopy (FT-IR) and Thermo gravimetric analysis (TGA) techniques. Drug compatibility study is carried out by FT-IR and powder X-ray diffraction (XRD) techniques. The physical properties and drug content of formulated tablets are evaluated and found to be optimum. In addition, in vitro drug release kinetics is carried out at two different pH, say, 1.2 and 6.8. The release pattern from different polymeric matrices is shown in figure below: a) Chitosan, HPMC K4M and HPMC K100M b) IPCs of CH/HPMC K4M in [2:3, 1:4 and 1:9 ratios] c) IPCs of CH/HPMC K100M in [2:3, 1:4 and 1:9 ratios]. From the study, it has been observed that the drug release is sustained for a period of 12h in 1:9 ratio of CH: K100M IPC due to the formation of complex network matrix.

Conclusion

In this study, we have successfully designed biocompatible IPC matrix as a drug carrier for highly water soluble metformin drug in order to control the release rate. Chitosan polymer could not sustain metformin release more than 30min. IPC matrices of CH/HPMC (K4M and K100M) have proved to be a useful drug carrier to retard the metformin release up to 12h. The high concentration and high viscosity grade of HPMC (K100M) are highly advantageous towards formation of complex network matrix favoring sustained release pattern. Thus, the designed IPCs prepared by hydrophilic polymers in varying proportions are quite promising for designing sustained oral drug delivery systems.