Pharmacology Of Nefazodone

Indication	For the treatment of depression.
Pharmacodynamics	Nefazodone, an antidepressant synthetically derived phenylpiperazine, is used to treat major depression. Although it is structurally similar to trazodone, nefazodone has a mechanism of action different from other antidepressants and, hence, lacks the risk for major cardiovascular toxicity seen with tricyclics and insomnia and inhibition of REM sleep seen with the selective serotonin reuptake inhibitors.
Mechanism of action	Within the serotonergic system, nefazodone acts as an antagonist at type 2 serotonin (5-HT2) post-synaptic receptors and, like fluoxetine-type antidepressants, inhibits pre-synaptic serotonin (5-HT) reuptake. These mechanisms increase the amount of serotonin available to interact with 5-HT receptors. Within the noradrenergic system, nefazodone inhibits norepinephrine uptake minimally. Nefazodone also antagonizes alpha(1)-adrenergic receptors, producing sedation, muscle relaxation, and a variety of cardiovascular effects. Nefazodone's affinity for benzodiazepine, cholinergic, dopaminergic, histaminic, and beta or alpha(2)-adrenergic receptors is not significant.
Absorption	Nefazodone is rapidly and completely absorbed. Its absolute bioavailability is low (about 20%).
Volume of distribution	0.22 to 0.87 L/kg
Protein binding	Greater than 99% (in vitro, human plasma proteins).
Metabolism	Hepatic.
Route of elimination	Nefazodone is extensively metabolized after oral administration by n-dealkylation and aliphatic and aromatic hydroxylation, and less than 1% of administered nefazodone is excreted unchanged in urine.
Half life	2-4 hours
Clearance	Not Available
Toxicity	Cases of life-threatening hepatic failure have been reported in patients treated with nefazodone.