Renal Contribution to Overall Metabolism of Drugs III: Metabolism of p-Aminobenzoic Acid

Simultaneous determination of p-aminobenzoic acid and its metabolites in the urine of volunteers, treated with p-aminobenzoic acid sunscreen formulation

“…Smaller amounts of 4-AHA and 4-OCH 3 -AHA were also found. These quantitative results are similar to those in published reports [18,29] showing serum levels in intravenous studies. The urine samples contained PABA, 4-AHA, 4-AMB, and 4-OCH 3 -AHA; PABA, 4-AHA, and 4-OCH 3 -AHA were not detected in the urine samples of some participants, because the amounts present were too small.…”

“…Analytical methodologies employing radioactive PABA cannot be used with live human skin as the substrate because of the hazardous nature of radioactive compounds. PABA is metabolized primarily by acetylation and glycine conjugation in the liver to form p-aminohippuric acid (4-AHA), p-acetamidobenzoic acid (4-AMB), and p-acetamidohippuric acid (4-OCH 3 -AHA), as shown in the following scheme [14,18]:…”

“…The metabolic processes of PABA in animals have been studied using high performance liquid chromatography with UV or fluorescence detection [14][15][16][17][18][19][20]. The percutaneous absorption and metabolism of PABA was determined in human skin [19] and in vitro through hairless guinea pig skin [20] using 14 Clabeled PABA. Analytical methodologies employing radioactive PABA cannot be used with live human skin as the substrate because of the hazardous nature of radioactive compounds.…”

Production of Acetylated Metabolites of Pesticides in Mammals

“…15) In vivo, N-acetylation is a typical and generally important metabolic reaction in mammals for many chemicals such as sulfanilamide and para-amino benzoic acid. 16,17) In previous rat metabolism studies of diethofencarb, an acetylated metabolite (3-ethoxy-4-hydroxyacetanilide) was detected in urine. 6, 7) However, no such acetylated metabolites of 5-23121 were found while aniline derivatives such as AMFE and AMFP could be identified in the feces and urine.…”

Measurement of the renal clearance of drugs.

“…The above approach has been used to estimate the renal contribution to the overall metabolism of methyldigoxin in man (Hinderling, Garrett & Wester, 1977), benzoic and p-aminobenzoic acids in animals (Wan & RiegeIman, 1972a;. Wan, Von Lehmann & Riegelman, 1972) and salicylic acid in animals and man (Wan & Riegelman, 1972b;Von Lehmann etal., 1973). Riegelman's group used simultaneous i.v.…”