Oxaprotiline, also known as hydroxymaprotiline, is a psychoactive drug

Psychoactive drug

A psychoactive drug, psychopharmaceutical, or psychotropic is a chemical substance that crosses the blood–brain barrier and acts primarily upon the central nervous system where it affects brain function, resulting in changes in perception, mood, consciousness, cognition, and behavior...

 and research chemical of the tetracyclic

Tetracyclic antidepressant

Tetracyclic antidepressants are a class of drugs used primarily as antidepressants that were first introduced in the 1970s. They are named after their chemical structure which contains four rings of atoms and are closely related to the tricyclic antidepressants which contain three rings of...

 chemical class. Though investigated as an antidepressant

Antidepressant

An antidepressant is a psychiatric medication used to alleviate mood disorders, such as major depression and dysthymia and anxiety disorders such as social anxiety disorder. According to Gelder, Mayou &*Geddes people with a depressive illness will experience a therapeutic effect to their mood;...

, it was never developed

Drug development

Drug development is a blanket term used to define the process of bringing a new drug to the market once a lead compound has been identified through the process of drug discovery...

 and marketed

Marketing

Marketing is the process used to determine what products or services may be of interest to customers, and the strategy to use in sales, communications and business development. It generates the strategy that underlies sales techniques, business communication, and business developments...

 for clinic

Clinic

A clinic is a health care facility that is primarily devoted to the care of outpatients...

al use.

Chemistry

Oxaprotiline is a racemic

Racemic

In chemistry, a racemic mixture, or racemate , is one that has equal amounts of left- and right-handed enantiomers of a chiral molecule. The first known racemic mixture was "racemic acid", which Louis Pasteur found to be a mixture of the two enantiomeric isomers of tartaric acid.- Nomenclature :A...

 compound composed of two isomer

Isomer

In chemistry, isomers are compounds with the same molecular formula but different structural formulas. Isomers do not necessarily share similar properties, unless they also have the same functional groups. There are many different classes of isomers, like stereoisomers, enantiomers, geometrical...

s, R(-)- or levo- oxaprotiline (levoprotiline; CGP-12,103-A), and S(+)- or dextro

Dextro

Dextro is the pseudonym given to the Scottish Falkirk born DIY musician, Ewan Mackenzie. Under the Dextro moniker he has released a number of works, most notably the albums Winded , Consequence Music and the 12" single Do You Need Help...

- oxaprotiline (dextroprotiline; CGP-12,104-A). Both enantiomers are active, with the levo- form acting merely as an antihistamine

Antihistamine

An H1 antagonist is a histamine antagonist of the H1 receptor that serves to reduce or eliminate effects mediated by histamine, an endogenous chemical mediator released during allergic reactions...

 and the dextro- form having a more expansive pharmacology (see below), but with both curiously still retaining antidepressant effects.

Pharmacology

Dextroprotiline acts as a potent

Potency (pharmacology)

In the field of pharmacology, potency is a measure of drug activity expressed in terms of the amount required to produce an effect of given intensity. A highly potent drug evokes a larger response at low concentrations, while a drug of lower potency evokes a small response at low concentrations...

 norepinephrine reuptake inhibitor

Norepinephrine reuptake inhibitor

A norepinephrine reuptake inhibitor or adrenergic reuptake inhibitor , is a type of drug which acts as a reuptake inhibitor for the neurotransmitters norepinephrine and epinephrine by blocking the action of the norepinephrine transporter...

 and H₁ receptor

H1 receptor

The H1 receptor is a histamine receptor belonging to the family of Rhodopsin like G-protein-coupled receptors. This receptor, which is activated by the biogenic amine histamine, is expressed throughout the body, to be specific, in smooth muscles, on vascular endothelial cells, in the heart, and in...

 antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

, as well as a very weak α₁-adrenergic receptor antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

. It has negligible affinity for the serotonin transporter

Serotonin transporter

The serotonin transporter is a monoamine transporter protein.This protein is an integral membrane protein that transports the neurotransmitter serotonin from synaptic spaces into presynaptic neurons. This transport of serotonin by the SERT protein terminates the action of serotonin and recycles it...

, dopamine transporter

Dopamine transporter

The dopamine transporter is a membrane-spanning protein that pumps the neurotransmitter dopamine out of the synapse back into cytosol, from which other transporters sequester DA and NE into vesicles for later storage and release...

, α₂-adrenergic receptor, and muscarinic acetylcholine receptor

Muscarinic acetylcholine receptor

Muscarinic receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled in the plasma membranes of certain neurons and other cells...

s. Whether it has any antagonistic

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

 effects on the 5-HT₂

5-HT2 receptor

The 5-HT2 receptors are a subfamily of 5-HT receptors that bind the endogenous neurotransmitter serotonin . The 5-HT2 subfamily consists of three G protein-coupled receptors which are coupled to Gq/G11 and mediate excitatory neurotransmission, including 5-HT2A, 5-HT2B, and 5-HT2C...

 or D₂ receptors like its relative maprotiline

Maprotiline

Maprotiline is a tetracyclic antidepressant . It is a strong norepinephrine reuptake inhibitor with only weak effects on serotonin and dopamine reuptake....

 is unclear.

Levoprotiline acts as a selective

Functional Selectivity

Functional selectivity is the ligand-dependent selectivity for certain signal transduction pathways in one and the same receptor. This can be present when a receptor has several possible signal transduction pathways...

 H₁ receptor

H1 receptor

The H1 receptor is a histamine receptor belonging to the family of Rhodopsin like G-protein-coupled receptors. This receptor, which is activated by the biogenic amine histamine, is expressed throughout the body, to be specific, in smooth muscles, on vascular endothelial cells, in the heart, and in...

 antagonist

Receptor antagonist

A receptor antagonist is a type of receptor ligand or drug that does not provoke a biological response itself upon binding to a receptor, but blocks or dampens agonist-mediated responses...

, with no affinity for adrenaline

Adrenergic receptor

The adrenergic receptors are a class of metabotropic G protein-coupled receptors that are targets of the catecholamines, especially noradrenaline and adrenaline ....

, dopamine

Dopamine receptor

Dopamine receptors are a class of metabotropic G protein-coupled receptors that are prominent in the vertebrate central nervous system . The neurotransmitter dopamine is the primary endogenous ligand for dopamine receptors....

, muscarinic acetylcholine

Muscarinic acetylcholine receptor

Muscarinic receptors, or mAChRs, are acetylcholine receptors that form G protein-coupled in the plasma membranes of certain neurons and other cells...

, or serotonin receptors

Receptor (biochemistry)

In biochemistry, a receptor is a molecule found on the surface of a cell, which receives specific chemical signals from neighbouring cells or the wider environment within an organism...

, or any of the monoamine transporter

Monoamine transporter

Monoamine transporters are protein structures that function as integral plasma membrane transporters to regulate concentrations of extracellular monoamine neurotransmitters. Three major classes of MATs are responsible for the reuptake of their associated amine neurotransmitters...

s.