Nefazodone, sold formerly under the brand names Serzone, Dutonin, and Nefadar among others, is an atypical antidepressant medication which is used in the treatment of depression and for other uses. Nefazodone is a phenylpiperazine derivative that combines serotonin 5-HT2A receptor antagonism with inhibition of serotonin reuptake and additional antagonism at alpha1-adrenergic and H1-histamine receptors; these combined pharmacologic actions account for antidepressant and anxiolytic effects as well as sedative and orthostatic adverse effects. The compound is orally administered and undergoes extensive hepatic metabolism, predominantly via CYP3A4, to active and inactive metabolites including hydroxynefazodone; its clinical use declined after reports of rare but severe hepatotoxicity. Nefazodone was withdrawn in most countries by 2004 due to cases of severe liver injury and subsequent regulatory restrictions, and remaining use has been limited to jurisdictions or special cases where regulatory authorities permitted restricted access.
Parent: Nefazodone
For active pharmaceutical ingredient control and regulatory compliance the impurity profile for nefazodone typically targets identification and quantification of related substances such as hydroxynefazodone, N-dealkylated derivatives, piperazine-related fragments and minor chlorinated or hydroxylated products formed during synthesis or metabolism, together with common process impurities and degradation products. Analytical control is usually performed by validated reversed-phase HPLC with UV detection and LC-MS for identification; typical specification limits used in API monographs and company specifications are in the range of each specified related compound not more than 0.5 percent by area or mass, unspecified individual impurities not more than 0.1 percent, total impurities not more than 2.0 percent, residual solvents controlled per ICH Q3C, and heavy metals kept below typical pharmacopeial limits (for example 10 to 20 parts per million depending on the applicable standard). Stability studies note oxidative and photolytic degradation pathways and require appropriate antioxidant protection and light shielding during storage and formulation.
Nefazodone is neither a classical selective serotonin reuptake inhibitor nor a serotonin norepinephrine reuptake inhibitor. It is best classified as an atypical antidepressant that combines serotonin 5-HT2A receptor antagonism with serotonin reuptake inhibition and additional receptor interactions such as alpha1-adrenergic antagonism.
Nefazodone was used primarily for major depressive disorder and related depressive conditions, and it was sometimes used off-label for anxiety and insomnia associated with depression. Due to safety concerns its use is now rare and has been discontinued or restricted in many countries.
Nefazodone and trazodone are chemically related phenylpiperazine antidepressants and share some pharmacologic features such as 5-HT2A antagonism and sedative properties, but they are distinct chemical entities with different metabolic profiles, receptor affinities and safety profiles.
Nefazodone was largely withdrawn because postmarketing reports and case reviews identified rare but serious hepatotoxicity including acute liver failure. Regulatory authorities responded with market withdrawals, label restrictions and limited availability, which substantially curtailed its use.
