Vraag
Gepost op: 6 maart 2013Stabiliteit van benzoylperoxide.
In de literatuur vinden we dat de afbraak van benzoylperoxide bevorderd wordt door citroenzuur. Welk mechanisme speelt hier ? Gaat dit dan ook op voor Na citraat ? De afbraak van benzoylperoxide is nl waarschijnlijk niet fysisch waar te nemen ... Vele bestaande formuleringen van shampoobasissen bevatten ofwel citroenzuur, ofwel Na citraat...
Antwoord
Benzoyl peroxide stability in pharmaceutical gel preparations.
Bollinger, JN. Lewis, D. Mendez, VM.
Journal of Pharmaceutical Sciences. 66(May): p 718-722. 1977.The storage stability of 10% benzoyl peroxide (I) in the presence of both individual and combined pharmaceutical gel ingredients was investigated. Gel systems contained carbomer 940 (carboxypolymethylene; Carbopol 940), hydroxypropyl methylcellulose and colloidal aluminum magnesium silicate (Veegum). Brij 30 (polyoxyethylene 4 lauryl ether; laureth 4) and Brij 35 (polyoxyethylene 23 lauryl ether; laureth 23) were used as surfactants. Propylene glycol 5% was used as the humectant and edetate disodium or citric acid as the chelating agent. I was quite unstable in the presence of nucleophilic agents and certain acidic substances. At both 30 and 40DG I was destroyed rapidly (within one month) in the presence of ethyl alcohol and acidic chelating agents. The substitution of acetone for ethyl alcohol, the elimination of chelating agents, and the addition of sodium hydroxide to gel preparations markedly reduced degradation. (6 refs.) (Modified author abstract)