Purpose: To develop sustained release matrix
tablets of diltiazem hydrochloride (DTZ) using modified
karaya gum (MK).
Methods: MK was prepared by cross-linking
karaya gum with tri-sodium tri-metaphosphate (STMP)
which was used as a cross linker. Matrix tablets of DTZ
were prepared using varying ratios of unmodified karaya
gum (K) and MK by direct compression. The matrix tablets
were evaluated for pharmacotechnical properties and in
vitro release. The optimized formulation was compared
with a reference, Dilzem® SR. MK and the
formulations were also characterized by scanning
electron microscopy (SEM), Fourier transform infra-red
spectroscopy (FTIR) and differential scanning
calorimetry (DSC).
Results: Tablets formulated with MK showed
higher mean dissolution time (MDT) and lower dissolution
efficiency than those prepared with karaya gum. Drug
release was by water uptake, diffusion and erosion
mechanisms. Drug release for tablets prepared with pure
K was 99.9 % at the end of 10 h while that tablet made
with MK was 68.2 % at the end of 12 h. MK sufficiently
controlled the drug release unlike K which exhibited
rapid drug release efficiency. SEM images of the tablets
before and after dissolution showed some morphological
changes on the tablet surface while FTIR and DSC
thermogram studies confirmed that there was no chemical
interaction between the drug and the polymers in MK
formulation. Formulation F6 compared well with Dilzem®
SR (reference) (p < 0.05) in terms of release
characteristics.
Conclusion: The results of the study demonstrate
that modified karaya gum is a potential matrix material
for formulating suitable sustained-release matrix
tablets of diltiazem.
Keywords: Karaya gum, Diltiazem
hydrochloride, Tri-Sodium tri-metaphosphate, Matrix tablets Sustained release.
