Formulation and In-Vivo Study of Diltiazem Hydrochloride Tablets Prepared Using Interpolymer Complexes

Aim: To investigate interpolymer complexes (IPCs) formation between carbopol and cationic polymers such as chitosan and Eudragit E for oral controlled drug delivery systems.
Methodology: The prepared IPCs were investigated using Fourier transform infra-red spectroscopy (FT-IR) and differential scanning calorimetry (DSC). Chitosan-carbopol and Eudragit E-carbopol IPCs loaded with diltiazem hydrochloride (DTZ HCl) with different drug:polymer ratios were also prepared. Diltiazem hydrochloride tablets were prepared using polymers alone, physical mixtures of chitosan or Eudragit E with carbopol and the corresponding drug loaded IPCs. In-vitro release studies were carried out in two dissolution media; 0.1 NHCl of pH 1.2 and phosphate buffer of pH 7.4.
Results: The dissolution rate of DTZ HCl from the prepared tablets were found to be dependant on the interaction between chitosan or Eudragit E with carbopol in the physical mixture, drug:polymer ratio and pH of the dissolution medium. Tablets prepared using chitosan – carbopol IPC, Eudragit E – carbopol IPC, and Eudragit E – carbopol physical mixture of drug:polymer ratio 1:5 were selected for the in-vivo study using rabbits. The results showed a lower peak plasma concentration and marked prolonged release effect of tablets containing Eudragit E – carbopol IPC and the corresponding physical mixture compared to that of commercial Altiazem tablets.
Conclusion: Tablets containing Eudragit E – carbopol or chitosan – carbopol physical mixtures showed prolonged drug release compared to that containing the corresponding IPCs, Furthermore, Eudragit E- carbopol matrix tablets showed slower drug release than that of chitosan – carbopol.