Oral Delivery of Proteins and Peptides: Concepts and Applications - Challenges in Delivery of Therapeutic Genomics and Proteomics - page 499

Xanthan gum anionic
polysaccharide derived from the
fermentation of plant bacteria
Xanthamonas campestris

l Soluble in hot or cold water and gives visually
hazy, neutral pH solutions
l Dissolves in hot glycerin
l Solutions typically in the 1500-2500 cps range at
1%; pseudoplastic and especially shear thinning.
In the presence of small amounts of salt, solution
shows good viscosity stability at elevated
temperatures
l Possesses excellent yield value in solutions

l More tolerant of electrolytes, acids, and bases than
most other organic gums
l Can, nevertheless, be gelled or precipitated with
certain polyvalent metal cations under specific
circumstances
l Very good viscosity stability over the pH 2-12 range
and good tolerance of water-miscible solvents shown
in solutions
l More compatible with most nonionic and
anionic gums, featuring useful synergism with
galactomannans
l More resistant to shear, heat, bacterial, enzyme, and
UV degradation than most gums

Guar gum (galactomannan
polysaccharide) empirical formula:
(C 6 H 12 O 6 ) n consists chiefly
of a high-molecular-weight
hydrocolloid polysaccharide
composed of galactan and mannan
units combined through glycosidic
linkages

l Obtained from the ground endosperms of the
seeds of Cyamopsis tetragonolobus (family
Leguminosae).
l MW approx. 220,000
l  2000-22,500 cps (1% aqueous solution)
l Forms viscous colloidal solution when hydrated in
cold water; optimum rate of hydration between pH
7.5 and 9.0.

l Stable in solution over a pH range of 1.0-10.5
l Viscosity degraded by prolonged heating
l Bacteriological stability is improved by the addition of
a mixture of 0.15% methyl paraben or 0.1% benzoic
acid.
l The FDA recognizes guar gum as a substance added
directly to human food and has been affirmed as
generally recognized as safe.
l Incompatible with acetone, tannins, strong acids, and
the alkalis. Borate ions, if present in the dispersing
water, will prevent hydration of guar.
l Used as a thickener for lotions and creams, as a tablet
binder, and as an emulsion stabilizer.

Hydroxypropyl Guar nonionic
derivative of guar, prepared by
reacting guar gum with propylene
oxide

l  in hot and cold water
l Gives high viscosity, pseudoplastic solutions that
show reversible decrease in viscosity at elevated
temperatures
l Lacks yield value

l Compatible with a high concentration of most salts
l Shows good tolerance of water-miscible solvents
l Better compatibility with minerals than guar gum
l Good viscosity stability in the pH range of 2-13.
l More resistance to bacterial and enzymatic degradation