PERCUTANEOUS-ABSORPTION OF IBUPROFEN - VEHICLE EFFECTS ON TRANSPORT THROUGH RAT SKIN

The transport of ibuprofen from propylene glycol vehicles through rat skin has been monitored in vitro. Skin stored for up to 4 months showed no significant change in its permeability to the drug but when the same tissue was used for consecutive experiments dramatic increases in flux were observed. Significant effects on drug permeation caused by vehicle composition and pH were found and solubilities and vehicle-skin partition coefficients were measured for all vehicles. As the concentration of propylene glycol increased permeation was related to the increase in solubility and reduction in partition coefficient. The pH effect was related to the degree of ionisation of the drug and to the effective concentration or degree of saturation when solutions were used. With suspensions of ibuprofen penetration rates were effectively independent of pH until high values were used when the vehicle interfered with the barrier properties of the skin.