Question
Posted on: June 8 2018A cream with gabapentin, Lidocaiine and Betamethasone dipropionate for Vulvodynie; Certain difficulties?
Our question focuses on the pH. Use Best buffered Cetomacrogol cream or not? For the stability of the gabapentin it is best to set a pH of 7.3 but what about the stability/efficacy of the Betamethasone edipropionate? The complete composition is: Gabapentin 8%; Lidocaine 0.15%; Betamethasone dipropionate 0.025%; Vaseline 10% and Cetomacrogol cream ad 50g
Answer
My information (Pharm. Research 1992; 9:595-600) gives a minimmal breakdown of gabapentin around a pH = 5.5. This pH is also good for the stability of Betamethasone dipropionate. For lidocaine I would use the hydrochloride. The solution has a pH of 5 to 7. So it seems appropriate to use the buffered Cetomacrogol cream here.