Chemical Properties
Low-substituted hydroxypropyl cellulose occurs as a white to
yellowish white powder or granules. It is odorless or has a slight,
characteristic odor, and it is tasteless.
Production Methods
Low-substituted hydroxypropyl cellulose is manufactured by
reacting alkaline cellulose with propylene oxide at elevated
temperature. Following the reaction, the product is recrystallized
by neutralization, washed, and milled.
Pharmaceutical Applications
Low-substituted hydroxypropyl cellulose is widely used in oral
solid-dosage forms. It is primarily used as a disintegrant, and as a
binder for tablets and granules in wet or dry granulation. It has
been used in the preparation of rapidly disintegrating tablets
produced by direct compression methods.In addition, lowsubstituted
hydroxypropyl cellulose has been used as a binder/
disintegrant included in the powder layering process on spherical
cores and to prepare pellets by extrusion/spheronization. A
low particle size and high hydroxypropyl content is recommended
to produce round spheres and rapid dissolution.
There are a number of grades that have different particle sizes
and substitution levels. LH-11 has the longest fibrous particles, and
is typically used as an anticapping agent and disintegrant for direct
compression. LH-21 is less fibrous and is used as a binder and
disintegrant for tablets through the wet-granulation process. LH-31
is a small-particle grade used especially for extrusion to produce
granules, as it has a small particle size that is better for passing a
screen. LH-B1 is the nonfibrous, high-density grade designed for
fluid-bed granulation, and can be used for direct compression and/
or formulations with a high low-substituted hydroxypropyl
cellulose loading. Lower substitution grades LH-22 and LH-32
can be used for better disintegration capability, depending on the
characteristics of the active ingredients.
The typical content of low-substituted hydroxypropyl cellulose
in a formulation is approximately 5–50%.
Safety
Low-substituted hydroxypropyl cellulose is generally regarded as a
nontoxic and nonirritant material.
Animal toxicity studies showed no adverse effects in rats fed
orally 6 g/kg/day over 6 months. No teratogenic effects were noted
in rabbits and rats fed 5 g/kg/day.
LD50 (rat, oral): >15 g/kg
storage
Low-substituted hydroxypropyl cellulose is a stable, though
hygroscopic, material. The powder should be stored in a wellclosed
container.
Incompatibilities
Alkaline substances may interact. If a tablet formulation contains
such a material, the disintegration time may be extended after
storage.
Regulatory Status
Included in the FDA Inactive Ingredients Database (oral capsules,
tablets, pellets). Approved for use in pharmaceuticals in Europe,
Japan, USA, and other countries. Included in the Canadian List of
Acceptable Non-medicinal Ingredients.
