Systemic absorption of topical salicylic acid.

The systemic absorption of salicylic acid in humans following topical application in either hydrophilic ointment or polyethylene glycol 400 vehicle was studied. Drug absorption was minimal following application to intact skin; however, measurable levels (8 mg/dl) were attained when the stratum corneum was removed prior to application of the drug in hydrophilic ointment. A one-compartment open model with first order absorption and elimination processes was fitted to the plasma salicylate concentrations as a function of time. Computer simulations predict that plasma salicylate levels associated with toxicity in some patients may be present after repetitive application of the drug in hydrophilic ointment.