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Question

Posted on: March 6 2013

How can the following preparation be made without hydrolyzing hydrocortisone acetate?

hydrocortisone acetate 0.2 g
Carbopol 940 0.5 g
Glycerol 2 g
NaOH 1N Q.S.
Water ad 30 g
< BR/> To increase the viscosity of the gel, NaOH is added to neutralize. The question is now: To obtain a maximum viscosity, the pH should be between 7 à 8. The problem is that hydrocortisone is found in the form of an acetate ester. Esters are susceptible to hydrolysis, and are most stable at a pH of 5.5. Is the Carbopolgel sufficiently neutralised to obtain a sufficiently high viscosity?
it Is not better to use a different type of carbopol (because of the Benzeenresidue & #039; s).

Answer

  1. the pH of a carbopolgel should not necessarily be between 7 to 8. Already at a pH of 6 the viscosity is sufficiently high. If necessary, increase the concentration of Carbopol. I would not alkalinize with NaOH certainly not when I setup at pH six. Compare with the composition of the NF.

     

  2. you would indeed be able to use a Carbopol from the newer series, which is less contaminated with benzene. But are they available at wholesale?

     

  3. it could well be that if using the alcoholic Carbopolgel one succeeds in preparing a clear gel!