Martin A. Erickson III, RPh
I am a pharmacy student in Wisconsin, and at my current practice site we have several doctors who prescribe a topical cream [ketoprofen 10%, gabapentin 6%, lidocaine 5%, and amitriptyline 2% in VaniCream] for pain in our patients. The ketoprofen is very difficult to suspend in this mixture. Do you have any tips on preparation?
First, please check with the prescriber about the therapy. Is this preparation intended for penetration of the active ingredient into a joint or for systemic absorption? In either case, the vehicle you mentioned does not contain a penetration enhancer per se. You might find patients obtain improved relief if you use a vehicle containing a penetration enhancer (eg, PLO gel, Pentravan).
The ketoprofen and other active ingredients should be reduced to a fine, uniform consistency by means of comminution with a ceramic or Wedgwood (not glass) mortar and pestle, after which a smooth paste should be made by adding a small amount of ethoxydiglycol, which solubilizes the ketoprofen nicely.
If this preparation’s emulsion is “breaking,” 2 different approaches can be taken to remedy this:
1) Using lidocaine as the base molecule and adding lidocaine hydrochloride 50:50 is often beneficial. If you use this approach, check the molecular weights to be sure you are incorporating sufficient lidocaine.
2) Decreasing the concentrations of the active ingredients and administering a larger quantity to obtain the same dose can also help. PT
Mr. Erickson is director of professional affairs at Gallipot Inc.