Chemical Properties
DE 0.75-0.85
Preparation
Derived from brown algae, also from alginic acid
Production Methods
Alginic acid, extracted from brown seaweed, is reacted with
propylene oxide to form propylene glycol alginate. Various grades
may be obtained that differ in composition according to the degree
of esterification and the percentage of free and neutralized carboxyl
groups present in the molecule; complete esterification of alginic
acid is impractical.
Pharmaceutical Applications
Propylene glycol alginate is used as a stabilizing, suspending,
gelling, and emulsifying agent in oral and topical pharmaceutical
formulations. Typically, a concentration of 0.3–5% w/v is used,
although this may vary depending upon the specific application and
the grade of propylene glycol alginate used.
Propylene glycol alginate is also used in cosmetics and food
products.
Safety
Propylene glycol alginate is used in oral and topical pharmaceutical
formulations, cosmetics, and food products. It is generally regarded
as a nontoxic and nonirritant material, although excessive oral
consumption may be harmful. A study in five healthy male
volunteers fed a daily intake of 175 mg/kg body-weight of
propylene glycol alginate for 7 days, followed by a daily intake of
200 mg/kg body-weight of propylene glycol alginate for a further 16
days, showed no significant adverse effects.
Inhalation of alginate dust may be irritant and has been
associated with industrially related asthma in workers involved in
alginate production. However, it appears that the cases of asthma
were linked to exposure to seaweed dust rather than pure alginate
dust.
(hamster, oral): 7.0 g/kg
(mouse, oral): 7.8 g/kg
(rabbit, oral): 7.6 g/kg
(rat, oral): 7.2 g/kg
storage
Propylene glycol alginate is a stable material, although it will
gradually become less soluble if stored at elevated temperatures for
extended periods.
Propylene glycol alginate solutions are most stable at pH 3–6. In
alkaline solutions, propylene glycol alginate is rapidly saponified.
Alginate solutions are susceptible to microbial spoilage and should
be sterilized or preserved with an antimicrobial preservative.
However, sterilization processes may adversely affect the viscosity
of propylene glycol alginate solutions; see Sodium Alginate.
The bulk material should be stored in an airtight container in a
cool, dry place.
Regulatory Status
GRAS listed. Accepted in Europe for use as a food additive.
Included in the FDA Inactive Ingredients Database (oral preparations).
Included in nonparenteral medicines licensed in the UK.
Included in the Canadian List of Acceptable Non-medicinal
Ingredients.
