Phenelzine, sold under the brand name Nardil, among others, is a nonselective and irreversible monoamine oxidase inhibitor (MAOI) of the hydrazine class which is used as an antidepressant and anxiolytic. Along with tranylcypromine and isocarboxazid, phenelzine is one of the few nonselective and irreversible MAOIs still in widespread clinical use. It is available in Australia, the United Kingdom, the United States, and Canada. It is taken by mouth. Indications
Phenelzine is used primarily in the treatment of major depressive disorder (MDD). Patients with depressive symptomology characterized as "atypical", "nonendogenous", and/or "neurotic" respond particularly well to phenelzine. The medication is also useful in patients who do not respond favorably to first and second-line treatments for depression, or are "treatment-resistant". In addition to being a recognized treatment for major depressive disorder, phenelzine is effective in treating dysthymia, bipolar depression (BD), panic disorder (PD), social anxiety disorder, bulimia, post-traumatic stress disorder (PTSD), and obsessive-compulsive disorder (OCD). Pharmacology
Pharmacodynamics
Phenelzine is a non-selective and irreversible inhibitor of the enzyme monoamine oxidase (MAO). It inhibits both of the respective isoforms of MAO, MAO-A and MAO-B, and does so almost equally, with slight preference for the former. By inhibiting MAO, phenelzine prevents the breakdown of the monoamine neurotransmitters serotonin, melatonin, norepinephrine, epinephrine, and dopamine, as well as the trace amine neuromodulators such as phenethylamine, tyramine, octopamine, and tryptamine. This leads to an increase in the extracellular concentrations of these neurochemicals and therefore an alteration in neurochemistry and neurotransmission. This action is thought to be the primary mediator in phenelzines therapeutic benefits.
Anyone taking phenelzine should inform their dentist before proceeding with dental surgery, and surgeon in any other contexts. Phenelzine has also been linked to vitamin B6 deficiency. Transaminases such as GABA-transaminase have been shown to be dependent upon vitamin B6 and may be involved in a potentially related process, since the phenelzine metabolite phenylethylidenehydrazine (PEH) is a GABA transaminase inhibitor. Both phenelzine and vitamin B6 are rendered inactive upon these reactions occurring. For this reason, it may be recommended to supplement with vitamin B6 while taking phenelzine. The pyridoxine form of B6 is recommended for supplementation, since this form has been shown to reduce hydrazine toxicity from phenelzine and, in contrast, the pyridoxal form has been shown to increase the toxicity of hydrazines. Research
Phenelzine showed promise in a phase II clinical trial from March 2020 in treating prostate cancer. Phenelzine has also been shown to have neuroprotective effects in animal models. History
Synthesis of phenelzine was first described by Emil Votoček and Otakar Leminger in 1932. See also
Phenylethylidenehydrazine
Hydrazine (antidepressant)
Isocarboxazid
Libby Zion Law (a case involving phenelzine and pethidine)
Monoamine oxidase inhibitor
Tranylcypromine

References
External links
"Phenelzine". Drug Information Portal. U.S. National Library of Medicine.