Percutaneous absorption of indomethacin from mixtures of fatty alcohol and propylene glycol (FAPG bases) through rat skin: effects of oleic acid added to FAPG base.

The effects of oleic acid (OA) added to mixtures of fatty alcohol and propylene glycol (FAPG bases) on the percutaneous absorption of indomethacin (ID) were investigated by using the abdominal skin of rats in vivo. The percutaneous absorption of propylene glycol (PG) from FAPG base was simultaneously examined. The percutaneous absorption of ID from FAPG bases in the absence of OA was poor as compared with that from FAPG bases containing OA. It was observed that when OA was added to the vehicles in the range of 5 to 30%, the percutaneous absorption of ID from the vehicles was increased. In particular, the maximal enhancement of percutaneous absorption of ID was achieved at 5% OA. However, the enhancing effect of percutaneous absorption of ID diminished when the OA content in the vehicle exceeded 50%. PG was readily absorbed through the rat skin from FAPG bases and its percutaneous absorption profiles were similar to those of ID. It can be presumed that PG and ID penetrate together through the skin. In addition, it was confirmed that the percutaneous absorption of ID and PG from FAPG bases was not affected by the viscosity of the vehicle. If FAPG base is to be used as a vehicle for the purpose of percutaneous absorption of ID, OA is considered to be a useful additive.