Appeal No. 2006-2248
Application No. 10/158,618
invention are sensitive to metal ions and in particular to bi- and tri-valent actions
and in certain instances, appear to degrade rapidly in their presence. The chelating
agent forms a complex with the metal ions thereby inactivating them and
preventing them from affecting the retinoid compounds. Chelating agents which
are useful in the compositions of this invention include ethylenediamine tetraacetic
acid (EDTA) and derivatives and salts thereof, dihydroxyethyl glycine, citric acid,
tartaric acid, and mixtures thereof. The chelating agents should be utilized in a
stabilizing effective amount and may range from about 0.01 to about 2% based on
the weight of the total composition, preferably from about 0.05 to about 1%
(col. 6, lines 45-59).
11. The pH of the compositions should be in the range of from
about 4 to about 9, and preferably from about 4 to about 7. Most preferably, the
pH of the compositions should be at least 5 (col. 7, lines 5-8).
12. Preferably, glycerin is included in the formulations of this
invention as a humectant, however, it should be present in relatively low amounts.
Preferably, the amount of glycerin should be less than 10% of the total
composition. More preferably, it should be less than 5% of the total composition
by weight. It is theorized that glycerin may enhance penetration of an active or
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