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Q: I am compounding a preparation intended to administer testosterone and dehydroepiandrosterone transdermally, but the gel keeps "breaking."I am using a carbomer/alcohol/water gel that is preserved and a small amount of ethanol as the levigating agent.
A: Compounding hormones and/or other active ingredients into gel basis for transdermal administration is a widely accepted pharmaceutical practice and is well-documented in the literature. Clinical observation and monitoring of appropriate markers during this therapy can be beneficial to the patientthe goal of extemporaneously compounded therapy is individual outcome. A key component of transdermal gels is of a penetration enhancer such as isopropyl palmitate/lecithin (50/50 w/w; Lipoil). In this combination, phospholipids/micelles are liberated from the solubilized lecithin. Phospholipids are well-known to aid the transport of active ingredients into the skin for absorption. The penetration enhancer usually is incorporated as 22% to 24% of the formulation and probably should be included here.
As to the "broken"gel, carbomer gels are pH-sensitive and also can break when overloaded with ingredients. Literature references point to the use of a poloxamer gel at 20% to 30% concentration in water (Pluronic F127 NF or Polox), a clear solution at refrigerated temperatures that becomes a semisolid at room-to-body temperatures. This behavior allows the material to remain in place where applied to the skin, instead of running off as a carbomer or methylcellulose gel might.
Mr. Erickson is director of professional affairs at Gallipot Inc.