/publications/issue/2006/2006-08/2006-08-5810

compounding HOTLINE

Author: Martin A. Erickson III, RPh

Q: The following formulation yields a gritty preparation for me. Could you offer some suggestions for improvement?

Gabapentin 5%
Lidocaine 15%
Ketoprofen 10%
Dimethyl sulfoxide (DMSO)5%
Pentravan qsad 30 g

Apply bid.

A: Elegance is the key to the evaluation of a compounded preparation and is the "art" side of pharmaceutical compounding. Elegance begins on the balance, in the mortar, and on the ointment slab. Adherence to technical procedures is important and is supported by artful performance of the process. Accurate, precise weighing, followed by reduction of powdered ingredients to impalpability (or nearly so)—using a ceramic or Wedgwood mortar and pestle (or an appropriate spatula and solid smooth surface)—is vital to preparation of a "smooth" ointment. In addition, an appropriate wetting agent should be employed to ensure dispersion of the powder(s) in the vehicle (ointment base).

I have a recommendation: reduce the powders to fine, impalpable consistency with a ceramic or Wedgwood mortar and pestle; add a small amount of DMSO with trituration to make a paste; then continue to add the rest of the DMSO with trituration. Transfer the resultant mass to a slab, and, using geometric dilution technique, levigate with Pentravan until all ingredients are combined.

Q: We have an order for carvedilol 0.4 mg (for a child) and wish to prepare a suspension from the tablet. Do you have any method for this?

A: Only one study related to the question was found: von Möllendorff E, Reiff K, Neugebauer G. Pharmacokinetics and bioavailability of carvedilol, a vasodilating beta-blocker. Eur J Clin Pharmacol. 1987;33(5):511-513.

The shelf stability or beyond-use date for the suspension was not reported. As with other similar situations, the conservative approach would be to make powder papers or capsules to be opened and mixed with a beverage (preferably water) at the time of administration.

Mr. Erickson is director of professional affairs at Gallipot Inc.

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