COMPOUNDING HOTLINE

Q Is there any reference for stability of squaric acid dibutyl ester in acetone? I know that it should be refrigerated, but how long is it still good to use?

A

Squaric acid dibutyl ester (quadratic acid dibutyl ester, the dibutyl ester of 3,4,-dihydroxy-3-cyclobutene-1,2-dione, or SADBE) has been studied for the treatment of alopecia areata. More recently, successful treatment of warts using SADBE 0.5% to 5% in acetone under occlusive dressing as an agent of contact immunotherapy has been reported in the literature. In one study, serial dilutions of SADBE in acetone were applied twice weekly to warts in children for 10 weeks. Of the patients who completed the study (148 of 188), 84% of the treated patients "showed complete clinical resolution with no significant side effects." The USP compounding monograph, <795>, suggests that, for nonaqueous formulations, 30 days or intended duration of therapy, whichever is earlier, be used as the "beyond-use" date, when the preparation is stored in a tight, light-resistant container at room temperature (unless, as here, the product must be stored in another fashion).

Squaric Acid Dibutyl Ester SolutionDibutyl Squarate SolutionSuggested Formula (30 mL)

0.1%

1%

Squaric Acid Dibutyl Ester

0.030 g

0.300 g

Acetone or 95% ethanol qs ad

30.000 mL

30.000 mL

Suggested Compounding Procedure

• Dissolve squaric acid in appropriate solvent (eg, acetone).
• Place in a light-resistant amber glass container (dropper bottle or applicator bottle with a glass dropper or glass rod).
• Store in refrigerator.

(Notes: No claims are made as to the uses, safety, efficacy, or bioavailability of this product. The formula is for informational purposes only.)

Procedure for Use

• Weigh container (with chemical) as received.
• Add measured quantity of acetone or 95% ethanol. Stir to dissolve material. Remove from container.
• Reweigh container to obtain weight of drug solvent solution.
• Perform necessary compounding calculations.

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