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Used to treat urea cycle disorders
Sodium phenylbutyrate helps remove ammonia from the body.
-Phenyl-butyrate (PB)4 is an aromatic fatty acid that is converted in vivo to phenylacetate (PA) by β-oxidation in liver and kidney mitochondria.
-In human body, phenylbutyrate is oxidized to phenylacetate, which is in turn conjugated with glutamine and eliminated in urine as phenylacetylglutamine, thereby mediating elimination of waste nitrogen
-Phenylbutyrate is one of the first drugs encountered in cancer therapy as a histone deacetylase inhibitor (HDACI).
-Butyric acid is one of the short-chain fatty acids produced by the gut microbiota through the fermentation of dietary fiber. Butyrate is primarily recognized for its beneficial effects in the colon and is tightly linked to gut health.
-Phenylbutyrate is a derivative of butyrate that has been chemically modified by the addition of a phenyl group. This structural change increases its lipophilicity (fat solubility) and alters its metabolic fate and biological activity. This allows it to be used as a systemic drug, in contrast to the locally produced butyrate in the gut, which is rapidly metabolized by colonocytes
Pathways:
-Histone deacetylase (HDAC) inhibitor
-ER stress inhibitor (at least in normal cell)
-Can act as a chemical chaperone, helping to reduce ER stress by facilitating proper protein folding.
-Modulation of NF-κB Signaling
-Changes in pathways such as PI3K/Akt/mTOR and MAPK.
-Some preclinical investigations have reported that treatment with phenylbutyrate leads to mitochondrial dysfunction and endoplasmic reticulum (ER) stress, both of which can result in an increase of ROS within cancer cells.
Note: Sodium butyrate (NaBu) vs Sodium phenylbutyrate
-Sodium butyrate is primarily a research tool with limited clinical application, whereas phenylbutyrate is used clinically
-Phenylbutyrate typically exhibits improved pharmacokinetics and is more amenable to systemic use compared to sodium butyrate.
-Both compounds act as HDAC inhibitors, phenylbutyrate additionally modulates ER stress and mitochondrial function, leading to potentially greater ROS production in certain cancer cells.