Method of controlling formation of imiquimod impurities

  • US 7,919,501 B2
  • Filed: 01/30/2010
  • Issued: 04/05/2011
  • Est. Priority Date: 12/17/2004
  • Status: Active Grant
First Claim
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1. A method of controlling formation of 1-(2-methylpropyl)-1H imidazo[4,5-c]quinolin-4-amine (imiquimod) related impurities in a pharmaceutical cream formulated with imiquimod and an oleic acid component during storage of the pharmaceutical cream prior to application of the pharmaceutical cream to a dermal or mucosal surface, said method comprising:

  • formulating the pharmaceutical cream with imiquimod and a pharmaceutically acceptable vehicle including an oleic acid component, wherein the oleic acid component contains at least about 80% oleic acid by weight as a fatty acid and has a peroxide value of no more than about 5 milliequivalents of oxygen per kilogram and contains less than about 1% by weight polar impurities at or prior to formulation of the pharmaceutical cream;

    storing the formulated pharmaceutical cream prior to use of the pharmaceutical cream; and

    forming a reduced amount of imiquimod-related impurities in the pharmaceutical cream during said storing of the pharmaceutical cream, as compared to an amount of imiquimod-related impurities formed in an identical pharmaceutical imiquimod cream but further formulated with butylated hydroxyanisole (BHA) when the pharmaceutical cream and the identical pharmaceutical imiquimod cream are each stored under identical storage conditions for up to about 6 months after formulation.

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