Antioxidants protect active ingredients from oxidation/degradation, and the antioxidants themselves will be oxidized and so their concentration will decrease. But in some regulations, they require that antioxidants should be stable as the active ingredient in a certain formulation. I think there is some contradiction.
I think the regulation is not wrong. I mean, the formulator should assure that antioxidants (and other APIs) in the formulation should have minimum concentrations during storage before expire (All pharmaceuticals must have expire date); this is valid also for antioxidant (e.g. Vit C). I think Pharmacopoeias have described the specification range (e.g. 105-95%) of each of drugs/API. If the antioxidant concentration is below the minimum requirement, the antioxidant cannot maintain the stability of the certain API. In our regulations (in Asean), preservatives and sweeteners should have also minimum concentrations and should be determined and reported
Dear Fuad,
of course antioxidants cannot be as stable as the API they are planned to protect.
Depending on the oxidative stress the drug product experiences, the antioxidant level will decrease over time. Already in manufacturing, there may be losses because excipients may contain relevant levels of oxidants, e.g. peroxides.
So the developers aim at optimizing all parameters including the antioxidant level to guarantee a reasonably stable product. This can be challenging because too high a concentration of antioxidants may be prooxidative!
So, at end of shelf-life, antioxidant concentrations will typically be lower than at manufacturing, which must not necessarily be the case for the API.
Best regards
Holger
This is in fact why antioxidants are used in the first place in food, pharmaceutical, and cosmetics. The main function of antoxidants is to prevent spoilage of these species since antioxidants will get oxidesed instead. Overtime, the concentration of these antioxidanta additives will decrease and this has to do with the expiration dates of the products. I agree with what the gentlemen before me have said. In conclusion, these antioxidants are added in calculated amounts depending on the product they are supposed to protect.
Sorry, but how can we know or determine the shelf life of an antioxidant?
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