Picolinamide is a poly (ADP-ribose) synthetase (PARP) inhibitor. PARP inhibitors, a group of pharmacological inhibitors of the enzyme poly ADP ribose polymerase (PARP), are developed for multiple indications, especially for the treatment of cancer. In vitro: The pathway of oxidation of picolinamide by a Gram-negative rod has been elucidated. Results showed that under high pH conditions, whole cells could release 2,5-dihydroxypyridine into culture supernatants. Moreover, sodium arsenite was able to cause whole cells to accumulate 6-hydroxypicolinate in the culture media. In addition, whole cells were found to oxidize picolinamide, without lag. It was also found that cell-free extracts could convert picolinamide into picolinate, and hydroxylate picolinate into 6-hydroxypicolinate . In vivo: Picolinamide was used in a previous study to evaluate the possibility that the inhibition of Na+/phosphate cotransport might be associated with the inhibition of NAD hydrolyzing enzymes. Results showed that the overnight treatment of rats with picolinamide, administered as a single injection (4 mmol/kg), could inhibit Na+/phosphate cotransport by isolated renal brush border membrane vesicles. Similar to nicotinamide, the inhibition caused by picolinamide occurred in thyroparathyroidectomized rats, was specific for Na+/phosphate cotransport. Unlike nicotinamide, there was only a small 1.5-fold increase in renal cortical NAD content after picolinamide treatment . Clinical trial: Up to now, picolinamide is still in the preclinical development stage.