International Numbering System (INS) for Food Additives: 406
Food additives Europe numbers: E406
Functional Category
Emulsifying agent;stabilizing agent; suppository base; suspending agent; sustained-release agent; tablet binder; thickening agent; viscosity-increasing agent
Applications in Pharmaceutical Formulation
Agar is widely used in food applications as a stabilizing agent. In pharmaceutical applications, agar is used in a handful of oral tablet and topical formulations. It has also been investigated in a number of experimental pharmaceutical applications including as a sustained-release agent in gels, beads, microspheres, and tablets.(1-4) It has also been reported to work as a disintegrant in tablets.(5) Agar has been used in a floating controlled-release tablet; the buoyancy in part being attributed to air entrapped in the agar gel network.(6) It can be used as a viscosity-increasing agent in aqueous systems. Agar can also be used as a base for nonmelting, and nondisintegrating suppositories.(7) Agar has an application as a suspending agent in pharmaceutical suspensions.
Description
Agar occurs as transparent, odorless, tasteless strips or as a coarse or fine powder. It may be weak yellowish-orange, yellowish-gray to pale-yellow colored, or colorless. Agar is tough when damp, brittle when dry
Stability and Storage Conditions:Agar solutions are most stable at pH 4–10. Agar should be stored in a cool, dry, place. Containers of this material may be hazardous when empty since they retain product residues (dust, solids)
Incompatibilities
Agar is incompatible with strong oxidizing agents. Agar is dehydrated and precipitated from solution by ethanol (95%). Tannic acid causes precipitation; electrolytes cause partial dehydration and decrease in viscosity of sols.(9)
Safety
Agar is widely used in food applications and has been used in oral and topical pharmaceutical applications. It is generally regarded as relatively nontoxic and nonirritant when used as an excipient. LD50 (hamster, oral): 6.1 g/kg(10) LD50 (mouse, oral): 16.0 g/kg LD50 (rabbit, oral): 5.8 g/kg LD50 (rat, oral): 11.0 g/kg