Functional Category
Flavoring agent.
Applications in Pharmaceutical Formulation
Vanillin is widely used as a flavor in pharmaceuticals, foods, beverages, and confectionery products, to which it imparts a characteristic taste and odor of natural vanilla. It is also used in perfumes, as an analytical reagent and as an intermediate in the synthesis of a number of pharmaceuticals, particularly methyldopa. Additionally, it has been investigated as a potential therapeutic agent in sickle cell anemia(1) and is claimed to have some antifungal properties.(2) In food applications, vanillin has been investigated as a preservative.(3,4) As a pharmaceutical excipient, vanillin is used in tablets, solutions (0.01–0.02% w/v), syrups, and powders to mask the unpleasant taste and odor characteristics of certain formulations, such as caffeine tablets and polythiazide tablets. It is similarly used in film coatings to mask the taste and odor of vitamin tablets. Vanillin has also been investigated as a photostabilizer in furosemide 1% w/v injection, haloperidol 0.5% w/v injection, and thiothixene 0.2% w/v injection.(5
Description
White or cream, crystalline needles or powder with characteristic vanilla odor and sweet taste.
Stability and Storage Conditions
Vanillin oxidizes slowly in moist air and is affected by light. Solutions of vanillin in ethanol decompose rapidly in light to give a yellow-colored, slightly bitter tasting solution of 6,60 -dihydroxy5,50 -dimethoxy-1,10 -biphenyl-3,30 -dicarbaldehyde. Alkaline solutions also decompose rapidly to give a brown-colored solution. However, solutions stable for several months may be produced by adding sodium metabisulfite 0.2% w/v as an antioxidant.(6) The bulk material should be stored in a well-closed container, protected from light, in a cool, dry place.
Incompatibilities
Incompatible with acetone, forming a brightly colored compound.(7) A compound practically insoluble in ethanol is formed with glycerin.
Safety
There have been few reports of adverse reactions to vanillin, although it has been speculated that cross-sensitization with other structurally similar molecules, such as benzoic acid, may occur.(8) Adverse reactions that have been reported include contact dermatitis(9) and bronchospasm caused by hypersensitivity.(10) The WHO has allocated an estimated acceptable daily intake for vanillin of up to 10 mg/kg body-weight.(11) LD50 (guinea pig, IP): 1.19 g/kg(12) LD50 (guinea pig, oral): 1.4 g/kg LD50 (mouse, IP): 0.48 g/kg LD50 (rat, IP): 1.16 g/kg LD50 (rat, oral): 1.58 g/kg LD50 (rat, SC): 1.5 g/kg