Is there a difference in SPEED of action of lidocaine (5%) Processed in buffered Cetomacrogol cream or in Carbomeergel?

This is a very difficult question especially when you focus on the "speed"! In any case, use lidocaine base. In the following reference: Preparation and characterization of two-phase melt systems of lidocaine, Lisheng Kang1, H. W. Jun and N. Mani, Department of Pharmaceutical and Biomedical Sciences, The University of Georgia College of Pharmacy, Athens, GA 30602, USA I found: Lidocaine 5, Menthol 0.6, ethanol 15g, Carbopol 980 1.0 g and water ad 100g.

It should also be possible to make an O/W cream in which the mixture of lidocaine and menthol is dissolved in Isopropyl Myristaat, which acts as an oil phase.