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.Key words: Karaya gum, Locust bean gum, Diltiazem hydrochloride, Sustained release, Hydroxypropyl methylcellulose
Highlights
Hydrophilic matrix tablets have long been used as a drug delivery system
The present study investigates karaya gum as a suitable, natural, low-cost hydrophilic matrix material for the formulation of sustained release tablets
This study demonstrates that its combination with khaya gum is synergistic in controlling diltiazem release
Summary
Hydrophilic matrix tablets have long been used as a drug delivery system This is due to their simplicity, cost-effectiveness, reduced risk of systemic toxicity, and minimal chance of dose dumping. Sometimes known as Sterculia gum, is the dried exudate of the Sterculia urens tree and other species of Sterculia. It is a complex polysaccharide of high molecular weight which, on hydrolysis, yields galactose, rhamnose and galacturonic acid. It occurs as a partially acetylated derivative and is compatible with other plant hydrocolloids as well as proteins and carbohydrates. Few works on karaya gum have been reported [6,7,8]
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