Abstract
Purpose: To develop sustained release matrix tablets of diltiazem
hydrochloride (DTZ) using karaya gum (K) alone or in combination with
locust bean gum (LB) and hydroxypropyl methylcellulose (H). Methods:
Matrix tablets of DTZ were prepared at different ratios of drug:gum
(1:1, 1:2, and 1:4) and of the gum blends (K, K/LB, K/H and K/LB/H) by
direct compression. The matrix tablets were evaluated for hardness,
friability, in vitro release and drug content. The formulations were
also characterised by scanning electron microscopy (SEM), Fourier
transform infra-red spectroscopy (FTIR) and differential scanning
calorimetry (DSC). A commercial diltiazem hydrochloride product Dilzem
SR, was used as a reference for comparison. Results: Tablets with only
K or K/H had the highest mean dissolution time (MDT), the least
dissolution efficiency (DE, 12 %), and released drug by swelling,
diffusion and erosion mechanisms. Karaya gum or combinations with
locust bean gum sufficiently controlled drug release, while
combinations of KH and KLBH exhibited high and low drug release
efficiency, respectively. SEM images of the tablets before and after
dissolution showed morphological changes on the tablet surface while
FTIR and DSC studies indicate that there was no chemical interaction
between the drug and the polymers. Three of the formulations compared
well with the reference (p < 0.05) in terms of release
characteristics. Conclusion: The results of the study demonstrate that
karaya gum alone or in suitable combination with locust bean gum and
hydroxypropyl methylcellulose is suitable for formulating
sustained-release matrix tablets of diltiazem.