The acyl glycerides of lipoic and dihydrolipoic acids may serve as slow-release sources for cutaneous delivery of these antioxidants when formulated in a liposomal vehicle. Accelerated storage testing was conducted to determine the storage stability of the lipoic derivatives and of the soybean phospholipids in which they were embedded. Lipoyl glycerides were incorporated into 110-nm diameter, unilamellar liposomes comprised of soybean phosphatidylcholine, cholesterol, lipoyl/dihydrolipoyl glycerides, and PEG-phospholipid. Dynamic light scattering measurements found no significant size change for vesicles incubated at 4 �C after 28 d, but liposomes treated at 25 �C and 40 �C increased in size/distribution, indicating some aggregation was occurring. The lipoyl glycerides were stable in the vesicles at 4 �C, but degraded slowly at 40 �C. Auto-oxidation of the liposomal phospholipids was also evaluated. Hydroperoxide accumulation was suppressed. These findings confirm the expectation that phospholipid liposomes are stable vehicles for dermal delivery of lipoic acid derivatives.

Long-term physical and oxidative stability of liposomes containing glycerides of lipoic acid

246th National Meeting (2013)

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