Compounding Hotline

Author: Martin A. Erickson III, RPh

Q: Do you have any info as to how to use spironolactone topically?

A: Spironolactone, a steroid with a structure similar to that of the endogenous adrenocorticoid aldosterone, occurs as a white or yellowish-white powder with a characteristic odor. It has a molecular weight of 416.6 and is practically insoluble in water and soluble in ethanol. It should be protected from light. Extemporaneously prepared oral suspensions have been reported to be stable for 60 to 90 days. It is a competitive antagonist of aldosterone in the distal portion of the renal tubule and is administered systemically as a potassium-sparing diuretic.

Spironolactone has antiandrogenic properties and has been studied as oral therapy for acne vulgaris where other methods of treatment failed; the reports have been positive. It has been included in topical formulations for acne, as well as for hirsutism. When used in this way, the results have been variable. Some research indicates that the vehicle for application and delivery may affect the response. One reported formulation employed 5% spironolactone in a gel vehicle applied for 8 weeks and showed a reduction of sebum secretion rates after 12 weeks. Possible gel vehicles are methylcellulose (5%- 8%) or Carbohol gel. The latter contains alcohol for improved solubility of the spironolactone. When compounding the preparation, ensure that the drug is finely triturated to impalpability with a ceramic or Wedgwood mortar and pestle; ensure homogeneity using geometric levigation technique and a levigating agent appropriate to the vehicle chosen.

One study suggested that chronic use of a topical formulation of spironolactone could affect blood pressure; the pharmacist may wish to advise the patient and physician and/or monitor the patient for this effect.

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

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