p-phenylenediamine

Endpoint summary

Additional information

p-Phenylenediamine hydrochloride will dissociate in situ, to the chloride ion and its corresponding cation. p-Phenylenediamine will also dissociate in situ to form the corresponding cation. In view of the species being the same regardless of whether the test substance is in its salt form or not, p-phenylenediamine hydrochloride is therefore representative of the substance.

Rats were administered 10 mg/kg of the test substance via a single i.p. dose, and excretion and distribution were determined for a 72-hour period. Approximately 50% of the dose was excreted in the urine, 35% in the feces, and 3-4% remained in the animal after 72 hours. Substantial animal variation in the distribution of excreted ¹⁴C activity was observed. Two metabolites were identified, with a 2:1 ratio of the major to minor components. The major metabolite co-chromatographed with the N,N’-diacetyl-PPD standard.

A study was conducted to compare the absorption of varying doses of (¹⁴C-labeled PPD; tested as the hydrochloride) test material through male rat skin. Only trace amounts of the test substance were present in the blood at any time and little of the material was eliminated in the urine and faeces in the low dose group. In the high dose group (12000 µg), the test material (or metabolites) were found to be present in blood, urine, and faeces in increased amounts. The authors conclude that the test substance enhances its own absorption and elimination.

As second study investigated the skin absorption of the test substance (¹⁴C-labeled PPD) in guinea pigs using a variety of patch test systems. The study demonstrated significant differences in absorption based on the type of patch/chamber system used. The authors reported a 6-fold difference in dermal absorption (statistically significant) over the range of test patch/chamber systems observed.