Flumezapine

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Flumezapine
Flumezapine.svg
FLUMEZAPINESPINGIF.gif
Identifiers
  • 7-Fluoro-2-methyl-4(4-methyl-1-piperazinyl)-10H-thieno(2,3b)(1,5)benzodiazepine
CAS Number
PubChem CID
UNII
KEGG
ChEMBL
CompTox Dashboard (EPA)
Chemical and physical data
Formula C17H19FN4S
Molar mass 330.43 g·mol−1
3D model (JSmol)
  • CC1=CC2=C(NC3=C(C=CC(=C3)F)N=C2S1)N4CCN(CC4)C

Flumezapine is an abandoned, investigational antipsychotic drug that was studied for the treatment of schizophrenia. Flumezapine failed clinical trials due to concern for liver and muscle toxicity. Flumezapine is structurally related to the common antipsychotic olanzapine—a point that was used against its manufacturer, Eli Lilly and Company, in a lawsuit in which generic manufacturers sought to void the patent on brand name olanzapine (Zyprexa). Although flumezapine does not differ greatly from olanzapine in terms of its structure, the difference was considered to be non-obvious, and Eli Lilly's patent rights on Zyprexa were upheld.

Contents

Medical uses

Flumezapine was studied for the treatment of schizophrenia. [1]

Adverse effects

In the clinical trial that lead to the cessation of its development as a drug, flumezapine was noted to be toxic. The administration of flumezapine led to the adverse effects of elevating the plasma concentration of creatine phosphokinase (CPK) and the liver enzymes aspartate transaminase (AST) and alanine transaminase (ALT). [1] These liver enzyme elevation risks are similar to that of the neuroleptic drug chlorpromazine. [1] Flumezapine also induced extrapyramidal symptoms (EPS) in patients during early clinical trials. [1]

Pharmacology

Flumezapine is classified as a second-generation antipsychotic, which includes other drugs such as clozapine. [2]

Mechanism of action

Flumezapine is an antipsychotic, due to its antagonism of dopamine receptors in the brain. However, like other antipsychotics, it also antagonizes other receptors in the brain, such as the muscarinic receptors. In comparison to clozapine, another antipsychotic, flumezapine's antidopaminergic to anticholinergic ratio is 5 times higher, indicating higher dopamine receptor blockade with less anticholingergic properties. [3]

Chemistry

Flumezapine is a thioeno[2,3-b][1,5]benzodiazepine akin to olanzapine, differing only by the substitution of a fluorine atom (F) for a hydrogen atom (H) on the phenyl ring. [4] The fluorine atom acts as an electron-withdrawing substituent; this was the same rationale given in the patent information for the electron-withdrawing chlorine atom on the antipsychotic clozapine. [5]

Flumezapine and olanzapine chemical structures, with explicit hydrogen shown on olanzapine for comparison. Flumez and OZP.jpg
Flumezapine and olanzapine chemical structures, with explicit hydrogen shown on olanzapine for comparison.

History

Developed alongside olanzapine by Eli Lilly and Company, the clinical development of flumezapine was halted due to toxicology concerns. [6] Its research designation was LY-120363. [7] The other analogues studied, (1) substituting flumezapine's methyl group for an ethyl group (ethyl flumezapine) [8] and (2) substituting flumezapine's methyl group for an ethyl group and its fluorine atom for a hydrogen atom, also failed due to concerns of granulocyte suppression and elevated cholesterol during in vivo studies on dogs, respectively. [9]

Society and culture

Controversies

In 2005, flumezapine was at the heart of a lawsuit filed by drug manufacturer Eli Lilly against three generic drug manufacturers (Zenith Goldline Pharmaceuticals, Dr. Reddy's Laboratories, and Teva Pharmaceuticals) that sought to develop generic versions of Zyprexa (olanzapine). [10] The generic companies claimed the Eli Lilly's patent on olanzapine was null and void due to the expiration of the similar compound, flumezapine, from which the discovery of olanzapine would be inevitable. [10] In the judge's ruling, the U.S. District Court for the Southern District of Indiana sided with Eli Lilly by upholding Eli Lilly's patent (Patent No. 5,229,382), finding that the substitution of a fluorine atom for a hydrogen atom in olanzapine was a non-obvious difference between the two compounds, which deserved continued patent protection. [10] [11] As Nicole L. M. Valtz writes in her commentary on the case,

"Mere identification in the prior art of each component of a composition does not render the combination obvious; the law requires some motivation to select and combine the references to reach the claimed invention." [12]

The selection patent was also upheld in Canada. [13] The patent for Zyprexa expired in 2011. [10]

Related Research Articles

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<span class="mw-page-title-main">Neuroleptic malignant syndrome</span> Medical condition

Neuroleptic malignant syndrome (NMS) is a rare but life-threatening reaction that can occur in response to neuroleptic or antipsychotic medication. Symptoms include high fever, confusion, rigid muscles, variable blood pressure, sweating, and fast heart rate. Complications may include rhabdomyolysis, high blood potassium, kidney failure, or seizures.

<span class="mw-page-title-main">Atypical antipsychotic</span> Class of pharmaceutical drugs

The atypical antipsychotics (AAP), also known as second generation antipsychotics (SGAs) and serotonin–dopamine antagonists (SDAs), are a group of antipsychotic drugs largely introduced after the 1970s and used to treat psychiatric conditions. Some atypical antipsychotics have received regulatory approval for schizophrenia, bipolar disorder, irritability in autism, and as an adjunct in major depressive disorder.

<span class="mw-page-title-main">Quetiapine</span> Atypical antipsychotic medication

Quetiapine, sold under the brand name Seroquel among others, is an atypical antipsychotic medication used for the treatment of schizophrenia, bipolar disorder, borderline personality disorder, and major depressive disorder. Despite being widely used as a sleep aid due to its sedating effect, the benefits of such use do not appear to generally outweigh the side effects. It is taken orally.

<span class="mw-page-title-main">Olanzapine</span> Atypical antipsychotic medication

Olanzapine is an atypical antipsychotic primarily used to treat schizophrenia and bipolar disorder. For schizophrenia, it can be used for both new-onset disease and long-term maintenance. It is taken by mouth or by injection into a muscle.

<span class="mw-page-title-main">Aripiprazole</span> Atypical antipsychotic

Aripiprazole, sold under the brand names Abilify and Aristada, among others, is an atypical antipsychotic. It is primarily used in the treatment of schizophrenia, obsessive compulsive disorder (OCD), and bipolar disorder; other uses include as an add-on treatment in major depressive disorder, tic disorders, and irritability associated with autism. Aripiprazole is taken by mouth or via injection into a muscle. A Cochrane review found low-quality evidence of effectiveness in treating schizophrenia.

<span class="mw-page-title-main">Dopaminergic</span> Substance related to dopamine functions

Dopaminergic means "related to dopamine" (literally, "working on dopamine"), dopamine being a common neurotransmitter. Dopaminergic substances or actions increase dopamine-related activity in the brain. Dopaminergic brain pathways facilitate dopamine-related activity. For example, certain proteins such as the dopamine transporter (DAT), vesicular monoamine transporter 2 (VMAT2), and dopamine receptors can be classified as dopaminergic, and neurons that synthesize or contain dopamine and synapses with dopamine receptors in them may also be labeled as dopaminergic. Enzymes that regulate the biosynthesis or metabolism of dopamine such as aromatic L-amino acid decarboxylase or DOPA decarboxylase, monoamine oxidase (MAO), and catechol O-methyl transferase (COMT) may be referred to as dopaminergic as well. Also, any endogenous or exogenous chemical substance that acts to affect dopamine receptors or dopamine release through indirect actions (for example, on neurons that synapse onto neurons that release dopamine or express dopamine receptors) can also be said to have dopaminergic effects, two prominent examples being opioids, which enhance dopamine release indirectly in the reward pathways, and some substituted amphetamines, which enhance dopamine release directly by binding to and inhibiting VMAT2.

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<span class="mw-page-title-main">Tricyclic</span> Organic compound having 3 fused rings

Tricyclics are cyclic chemical compounds that contain three fused rings of atoms.

<span class="mw-page-title-main">Olanzapine/fluoxetine</span> Antidepressant medication

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<span class="mw-page-title-main">Sultopride</span> Chemical compound

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<span class="mw-page-title-main">Blonanserin</span> Atypical antipsychotic

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References

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