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No data are available for hydroxypivalic acid neopentylglycol ester (HPN). However, the substance is expected to be rapidly absorbed after uptake and cleaved by ubiquitanious esterases to hydroxypivalic acid (CAS 4835 -90 -9) and neopentylglycol (NPG, CAS 126 -30 -7).

Like pivalic acid hydroxypivalic acid is expected to be relatively resistant to biotransformation due to the quaternary structure and do not readily form bioactive metabolites. Since neoacids like hydroxapivalic acid are not readily metabolized they would primarily be eliminated in the urine as glucoronic acid conjugates, carnitine conjugate or by dealkylation (Source: Hazard Characterization for Neoacids C5 TO C28, ). Due to their structural similarity to NPG (se below) glucoronic acid conjugation and extraction via urine is expected to be the preferred metabolism pathway.

In the study on the expected metabolite neopentylglycol (NPG) reported by Gessner et al. (1960; study meets scientific standards with acceptable restrictions) each of 4 rabbits was gavaged with 1000 -1500 mg/kg bw unlabelled NPG and excretion of the test substance and their metabolites via urine was determined the following 24 h (pooled data). After oral application 62% (range 53-67%) of the applied dose was found in the 24-h urine as the conjugate of glucuronic acid indicating rapid absorption. Only 1.9% of the applied dose was excreted as 3-hydroxy-2,2-dimethylpropionic acid and 0.7% as unchanged neopentyl glycol. 3-hydroxy-2,2-dimethylpropionic acid is also called hydroxypivalic acid which is the second cleavage product of HPN (see above).

Conclusion: HPN is expected to be rapidly cleaved by esterases to NPG and hydroxypivalic acid followed by conjugation of each metabolite with glucuronic acid and excretion via urine.