Question
Posted on: March 6 2013How can the following preparation be made without hydrolyzing hydrocortisone acetate?
hydrocortisone acetate 0.2 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?
Carbopol 940 0.5 g
Glycerol 2 g
NaOH 1N Q.S.
Water ad 30 g
it Is not better to use a different type of carbopol (because of the Benzeenresidue & #039; s).
Answer
- 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.
- 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?
- it could well be that if using the alcoholic Carbopolgel one succeeds in preparing a clear gel!