Pharmacokinetic study on the percutaneous absorption of p-aminobenzoic acid from three sunscreen preparations
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A urinary excretion study was conducted in six healthy male subjects to evaluate the percutaneous absorption of p-aminobenzoic acid (PABA) from three sunscreen preparations. The study was a crossover design and urine samples were collected during 48 hours after the application of the sunscreen preparations on the face, neck trunk and upper extremities. the volunteers also received a 500 mg dose of PABA orally. No statistically significant differences in the total amount recovered in the urine were found between the three kinds of formulations, but a great intersubject variation was observed. When PABA was given orally 50.5% to 83,1% was excreted as acetylated derivative. However, when the compund was applied topically the degree of metabolization of PABA increased significantly and the level of acetylated PABA excreted fluctuated between 69,7% and 90,2%.