In vitro percutaneous absorption of thiamine disulfide from a mixture of propylene glycol and fatty acid

The in vitro percutaneous transport of thiamine disulfide (TDS), an oxidized dimer of thiamine, from propylene glycol through excised abdominal rat skin was studied. The application of saturated, long-chain fatty acids [stearic acid (18:0), myristic acid (14:0), and lauric acid (12:0)] as enhancers to the system was also studied. TDS permeated through rat skin from propylene glycol with a flux of 2.5 +/- 0.8 micrograms/cm2/min. The flux was enhanced 31 times by 12:0 and 1.4 times by 14:0 and was suppressed to 80% of its original value by 18:0. The absorption of TDS could not be explained by TDS permeating across a dialysis membrane, but the interaction between TDS and fatty acids may influence the system. The results show the possibility of developing a transdermal thiamine delivery system.