Khaya gum:Khaya gum is a polysaccha

Khaya gum:
Khaya gum is a polysaccharide obtained from the incised
trunk of the tree Khaya grandifoliola (family Meliaceae). It isknown to contain highly branched polysaccharides consisting
of D galactose, L-rhamnose, D-galacturonic acid and 4-O-
60 methyl-D-glucoronic acid . Khaya gum has been shown to
be useful as a binding agent in tablet formulations. Khaya
gum is a hydrophilic polymer and has been shown to possess
emulsifying properties comparable with acacia gum. The fact
that the gum is naturally available, inexpensive and non-toxic
has also fostered the interest in developing the gum for
pharmaceutical use. Further work has also shown its potential
as a directly compressible matrix system in the formulation of
61 controlled release tablets .
Khaya gum has been successfully evaluated as a controlled
r e l e a s e a g e n t i n c o m p a r i s o n w i t h
hydroxypropylmethylcellulose (HPMC) using paracetamol
(water soluble) and indomethacin (water insoluble) as model
drugs. Tablets were produced by direct compression and the
in-vitro drug release was assessed in conditions mimicking
the gastrointestinal system. Khaya gum matrices provided a
controlled release of paracetamol for up to 5 h. The release of
paracetamol from khaya gum matrices followed timeindependent
kinetics and release rates were dependent on the
concentration of the drug present in the matrix. A combination
of khaya gum and HPMC gave zero-order time-independent
62 release kinetics .
In another study Khaya and albizia gums were evaluated as
compression coatings for target drug delivery to the colon
using indomethacin and paracetamol as model drugs. The
core tablets were compression-coated with 300 and 400 mg of
khaya gum & albizia gum respectively and also a mixture of
khaya and albizia gum (1:1). Drug release studies indicated
that khaya and albizia gums were capable of protecting the
core tablet in the physiological environment of the stomach
and small intestine, with albizia gum showing greater ability
than khaya gum. The release from tablets coated with the
mixture of khaya and albizia gums was midway between the
two individual gums, indicating that there was no interaction
between the gums. Studies carried out using rat caecal matter
in phosphate-buffered saline at pH 6.8 (simulated colonic
fluid) showed that the gums were susceptible to degradation
by the colonic bacterial enzymes, leading to release of the
drug. The results demonstrate that khaya gum and albizia gum
61 have potential for drug targeting to the colon .