Compounding Hotline

MARCH 01, 2006
Martin A. Erickson III, RPh

Q: Have you seen a formulation for sodium bicarbonate mouthwash 500 mL? The prescriber did not specify concentration.

A: Sodium bicarbonate has been used as a stomachic and in carminative mixtures. The Indian National Formulary gave "Sodium Bicarbonate Compound Mixture" as sodium bicarbonate 300 mg, chloroform spirit 0.6 mL, compound cardamom tincture 1 mL, aromatic ammonia spirit 1 mL, ginger syrup 2 mL, and fennel water qs ad 15 mL. (Note: chloroform is no longer permitted as an ingredient in products for human use in the United States.)

The British Pharmaceutical Codex and the British National Formulary 1974 gave "Paediatric [sic] Sodium Bicarbonate Mixture" (the latter volume placed "Paediatric" at the end of the title) as "Sodium bicarbonate 50 mg, ginger syrup 0.2 mL, concentrated dill water 0.1 mL, syrup 1.85 mL, double-strength chloroform water 2.5 mL, water qs ad 5 mL. It should be recently prepared." (See the chloroform comment above.)

It would seem prudent to contact the prescriber to discuss his or her intentions regarding the use of the product and the final concentration desired.

Q: I am trying to prepare a vaginal douche and need to measure 18 mg of menthol. My scale does not measure milligrams—it measures only grams. I was thinking of using the aliquot method, but menthol is only slightly soluble in water.

A: Although alcohol (pharmaceutical alcohol is ethanol) generally is not used vaginally, the solubility of menthol in 200-proof ethanol is 1 part in <1 part solvent ("very soluble"). A dilution aliquot compounded with alcohol could provide the needed solubilized menthol. Allowed to stand in open air, ethanol will evaporate, and the menthol will remain.

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

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