Talk:Phenelzine

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Summary sheet: Phenelzine

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History and culture

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Chemistry

{{Phenelzine is administered orally in the form of phenelzine sulfate and is rapidly absorbed from the gastrointestinal tract. Time to peak plasma concentration is 43 minutes and half-life is 11.6 hours. Unlike most other drugs, phenelzine irreversibly disables MAO, and as a result, it does not necessarily need to be present in the blood at all times for its effects to be sustained. Because of this, upon phenelzine treatment being ceased, its effects typically do not actually wear off until the body replenishes its enzyme stores, a process which can take as long as 2–3 weeks.

Phenelzine is metabolized primarily in the liver and its metabolites are excreted in the urine. Oxidation is the primary routine of metabolism, and the major metabolites are phenylacetic acid and parahydroxyphenylacetic acid, recovered as about 73% of the excreted dose of phenelzine in the urine over the course of 96 hours after single doses. Acetylation to N2-acetylphenelzine is a minor pathway. Phenelzine may also interact with cytochrome P450 enzymes, inactivating these enzymes through formation of a heme adduct. Two other minor metabolites of phenelzine, as mentioned above, include phenylethylidenehydrazine and phenethylamine. }}

Pharmacology

{{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 phenelzine's therapeutic benefits.

Phenelzine and its metabolites also inhibit at least two other enzymes to a lesser extent, of which are alanine transaminase (ALA-T),[9] and γ-Aminobutyric acid transaminase (GABA-T),[10] the latter of which is not caused by phenelzine itself, but by a phenelzine metabolite phenylethylidenehydrazine (PEH). By inhibiting ALA-T and GABA-T, phenelzine causes an increase in the alanine and GABA levels in the brain and body. GABA is the major inhibitory neurotransmitter in the mammalian central nervous system, and is very important for the normal suppression of anxiety, stress, and depression. Phenelzine's action in increasing GABA concentrations may significantly contribute to its antidepressant, and especially, anxiolytic/antipanic properties, the latter of which have been considered superior to those of other antidepressants. As for ALA-T inhibition, though the consequences of disabling this enzyme are currently not well understood, there is some evidence to suggest that it is this action of the hydrazines (including phenelzine) which may be responsible for the occasional incidence of hepatitis and liver failure.

Phenelzine has also been shown to metabolize to phenethylamine (PEA).[11] PEA acts as a releasing agent of norepinephrine and dopamine, and produces effects very similar to those of amphetamine, though with markedly different pharmacokinetics such as a far shorter duration of action. Phenelzine's enhancement of PEA levels may contribute further to its overall antidepressant effects to some degree. In addition, phenethylamine is a substrate for MAO-B, and treatment with MAOIs that inhibit MAO-B such as phenelzine have been shown to consistently and significantly elevate its concentrations.

Like many other antidepressants, phenelzine usually requires several weeks of treatment to achieve full therapeutic effects. The reason for this delay is not fully understood, but it is believed to be due to many factors, including achieving steady-state levels of MAO inhibition and the resulting adaptations in mean neurotransmitter levels, the possibility of necessary desensitization of autoreceptors which normally inhibit the release of neurotransmitters like serotonin and dopamine, and also the upregulation of enzymes such as serotonin N-acetyltransferase. Typically, a therapeutic response to MAOIs is associated with an inhibition of at least 80-85% of monoamine oxidase activity.[12] }}

Subjective effects

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The effects listed below are based on the subjective effect index, which is based on anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be treated with a healthy amount of skepticism. It is worth noting that these effects will rarely (if ever) occur all at once but heavier doses will increase the chances of inducing a full range of effects. Likewise, adverse effects become much more likely on higher doses and may include serious injury or death.

Physical effects
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Visual effects
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Cognitive effects
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Auditory effects
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Multi-sensory effects
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Transpersonal effects
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Experience reports

There are currently no anecdotal reports which describe the effects of this compound within our experience index. Additional experience reports can be found here:

Toxicity and harm potential

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We also recommend that you conduct independent research and use harm reduction practices when using this substance.

It is strongly recommended that one use harm reduction practices when using this substance.

Lethal dosage

Tolerance and addiction potential

Dangerous interactions

{{The MAOIs are infamous for their problematic food restrictions and drug interactions. Hypertensive crisis may result from the overconsumption of tyramine-containing foods. As a result, patients on phenelzine and other MAOIs must avoid excess quantities of certain foods that contain tyramine such as aged cheeses and cured meats, among others. Serotonin syndrome may result from an interaction with certain drugs which increase serotonin activity such as selective serotonin reuptake inhibitors, serotonin releasing agents, and serotonin agonists. Several deaths have been reported due to drug interaction-related serotonin syndrome such as the case of Libby Zion. }} Although many psychoactive substances are reasonably safe to use on their own, they can quickly become dangerous or even life-threatening when taken with other substances. The following lists some known dangerous combinations, but cannot be guaranteed to include all of them. Independent research should always be conducted to ensure that a combination of two or more substances is safe to consume. Some interactions listed have been sourced from TripSit.

Legal status

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See also

External links

Literature

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References