Clinical data | |
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Pronunciation | A-mox-a-peen [1] |
Trade names | Asendin, others |
AHFS/Drugs.com | Monograph |
MedlinePlus | a682202 |
License data | |
Routes of administration | Oral |
ATC code | |
Legal status | |
Legal status | |
Pharmacokinetic data | |
Bioavailability | >60% [3] |
Protein binding | 90% [4] |
Metabolism | Hepatic (cytochrome P450 system) [3] |
Elimination half-life | 8–10 hours (30 hours for chief active metabolite) [4] |
Excretion | Renal (60%), feces (18%) [3] |
Identifiers | |
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CAS Number | |
PubChem CID | |
IUPHAR/BPS | |
DrugBank | |
ChemSpider | |
UNII | |
KEGG | |
ChEBI | |
ChEMBL | |
CompTox Dashboard (EPA) | |
ECHA InfoCard | 100.034.411 |
Chemical and physical data | |
Formula | C17H16ClN3O |
Molar mass | 313.79 g·mol−1 |
3D model (JSmol) | |
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Amoxapine, sold under the brand name Asendin among others, is a tricyclic antidepressant (TCA). It is the N-demethylated metabolite of loxapine. Amoxapine first received marketing approval in the United States in 1980, approximately 10 to 20 years after most of the other TCAs were introduced in the United States. [5]
Amoxapine is used in the treatment of major depressive disorder. Compared to other antidepressants it is believed to have a faster onset of action, with therapeutic effects seen within four to seven days. [6] [7] In excess of 80% of patients that do respond to amoxapine are reported to respond within two weeks of the beginning of treatment. [8] It also has properties similar to those of the atypical antipsychotics, [9] [10] [11] and may behave as one [12] [13] and thus may be used in the treatment of schizophrenia off-label. Despite its apparent lack of extrapyramidal side effects in patients with schizophrenia it has been found to exacerbate motor symptoms in patients with Parkinson's disease and psychosis. [14]
As with all FDA-approved antidepressants it carries a black-box warning about the potential of an increase in suicidal thoughts or behaviour in children, adolescents and young adults under the age of 25. [3] Its use is also advised against in individuals with known hypersensitivities to either amoxapine or other ingredients in its oral formulations. [3] Its use is also recommended against in the following disease states: [3]
Its use is also advised against in individuals concurrently on monoamine oxidase inhibitors or if they have been on one in the past 14 days and in individuals on drugs that are known to prolong the QT interval (e.g. ondansetron, citalopram, pimozide, sertindole, ziprasidone, haloperidol, chlorpromazine, thioridazine, etc.). [3]
Its use in breastfeeding mothers not recommended as it is excreted in breast milk and the concentration found in breast milk is approximately a quarter that of the maternal serum level. [6] [15]
Adverse effects by incidence: [3] [16]
Note: Serious (that is, those that can either result in permanent injury or are irreversible or are potentially life-threatening) are written in bold text.
Very common (>10% incidence) adverse effects include:
Common (1–10% incidence) adverse effects include:
Uncommon/Rare (<1% incidence) adverse effects include:
Unknown incidence or relationship to drug treatment adverse effects include:
It tends to produce less anticholinergic effects, sedation and weight gain than some of the earlier TCAs (e.g. amitriptyline, clomipramine, doxepin, imipramine, trimipramine). [17] It may also be less cardiotoxic than its predecessors. [18]
It is considered particularly toxic in overdose, [19] with a high rate of renal failure (which usually takes 2–5 days), rhabdomyolysis, coma, seizures and even status epilepticus. [18] Some believe it to be less cardiotoxic than other TCAs in overdose, although reports of cardiotoxic overdoses have been made. [6] [16]
Site | Ki (nM) | Species | Ref |
---|---|---|---|
SERT Tooltip Serotonin transporter | 58 | Human | [21] |
NET Tooltip Norepinephrine transporter | 16 | Human | [21] |
DAT Tooltip Dopamine transporter | 4,310 | Human | [21] |
5-HT2A | 0.5 | Human | [22] |
5-HT2C | 2.0 | Monkey | [23] |
5-HT6 | 6.0–50 | Human | [23] [24] |
5-HT7 | 41 | Monkey | [23] |
α1 | 50 | Human | [25] |
α2 | 2,600 | Human | [25] |
D2 | 3.6–160 | Human | [26] [22] [25] |
D3 | 11 | Human | [22] |
D4 | 2.0–40 | Human | [22] |
H1 | 7.9–25 | Human | [27] [25] |
H2 | ND | ND | ND |
H3 | >100,000 | Human | [27] |
H4 | 6,310 | Human | [27] |
mACh Tooltip Muscarinic acetylcholine receptor | 1,000 | Human | [25] |
Values are Ki (nM). The smaller the value, the more strongly the drug binds to the site. |
Amoxapine possesses a wide array of pharmacological effects. It is a moderate and strong reuptake inhibitor of serotonin and norepinephrine, respectively, [21] and binds to the 5-HT2A, [28] 5-HT2B, [29] 5-HT2C, [28] 5-HT3, [30] 5-HT6, [23] 5-HT7, [23] D2, [25] α1-adrenergic, [25] D3, [26] D4, [26] and H1 receptors [25] with varying but significant affinity, where it acts as an antagonist (or inverse agonist depending on the receptor in question) at all sites. It has weak but negligible affinity for the dopamine transporter and the 5-HT1A, [30] 5-HT1B, [30] D1, [31] α2-adrenergic, [25] H4, [32] mACh, [25] and GABAA receptors, [31] and no affinity for the β-adrenergic receptors or the allosteric benzodiazepine site on the GABAA receptor. [31] Amoxapine is also a weak GlyT2 blocker, [33] as well as a weak (Ki = 2.5 μM, EC50 = 0.98 μM) δ-opioid receptor partial agonist. [34]
7-Hydroxyamoxapine, a major active metabolite of amoxapine, is a more potent dopamine receptor antagonist and contributes to its neuroleptic efficacy, [9] whereas 8-hydroxyamoxapine is a norepinephrine reuptake inhibitor but a stronger serotonin reuptake inhibitor and helps to balance amoxapine's ratio of serotonin to norepinephrine transporter blockade. [35]
Amoxapine is metabolised into two main active metabolites: 7-hydroxyamoxapine and 8-hydroxyamoxapine. [36]
Compound [36] [37] [38] | t1/2 (hr) [39] | tmax (hr) | CSS (ng/mL) | Protein binding [3] | Vd [3] | Excretion [3] |
---|---|---|---|---|---|---|
Amoxapine | 8 | 1-2 | 17-93 ng/mL (divided dosing), 13-209 ng/mL (single daily dosing) | 90% | 0.9-1.2 L/kg | Urine (60%), feces (18%) |
8-hydroxyamoxapine | 30 | 5.3 (single dosing) | 158-512 ng/mL (divided dosing), 143-593 ng/mL (single dose) | ? | ? | ? |
7-hydroxyamoxapine | 6.5 | 2.6-5.4 (single dosing) | ? | ? | ? | ? |
Where:
Brand names for amoxapine include (where † denotes discontinued brands): [6] [40]
An anxiolytic is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiety disorders and their related psychological and physical symptoms.
Tricyclic antidepressants (TCAs) are a class of medications that are used primarily as antidepressants, which is important for the management of depression. They are second-line drugs next to SSRIs and SNRIs. TCAs were discovered in the early 1950s and were marketed later in the decade. They are named after their chemical structure, which contains three rings of atoms.
Tetracyclic antidepressants (TeCAs), which contain four rings of atoms, are a closely related group of antidepressant compounds.
Quetiapine, sold under the brand name Seroquel among others, is an atypical antipsychotic medication used for the treatment of schizophrenia, bipolar 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.
Tetracyclic antidepressants (TeCAs) are a class of antidepressants that were first introduced in the 1970s. They are named after their tetracyclic chemical structure, containing four rings of atoms, and are closely related to the tricyclic antidepressants (TCAs), which contain three rings of atoms.
Loxapine, sold under the brand names Loxitane and Adasuve among others, is a tricyclic antipsychotic medication used primarily in the treatment of schizophrenia. The medicine is a member of the dibenzoxazepine class and structurally very similar to clozapine. Several researchers have argued that loxapine, initially classified as a typical antipsychotic, behaves as an atypical antipsychotic.
Mirtazapine, sold under the brand name Remeron amongst others, is an atypical tetracyclic antidepressant, and as such is used primarily to treat depression. Its effects may take up to four weeks, but can also manifest as early as one to two weeks. It is often used in cases of depression complicated by anxiety or insomnia. The effectiveness of mirtazapine is comparable to other commonly prescribed antidepressants. It is taken by mouth.
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A dopamine antagonist, also known as an anti-dopaminergic and a dopamine receptor antagonist (DRA), is a type of drug which blocks dopamine receptors by receptor antagonism. Most antipsychotics are dopamine antagonists, and as such they have found use in treating schizophrenia, bipolar disorder, and stimulant psychosis. Several other dopamine antagonists are antiemetics used in the treatment of nausea and vomiting.
Desipramine, sold under the brand name Norpramin among others, is a tricyclic antidepressant (TCA) used in the treatment of depression. It acts as a relatively selective norepinephrine reuptake inhibitor, though it does also have other activities such as weak serotonin reuptake inhibitory, α1-blocking, antihistamine, and anticholinergic effects. The drug is not considered a first-line treatment for depression since the introduction of selective serotonin reuptake inhibitor (SSRI) antidepressants, which have fewer side effects and are safer in overdose.
Trimipramine, sold under the brand name Surmontil among others, is a tricyclic antidepressant (TCA) which is used to treat depression. It has also been used for its sedative, anxiolytic, and weak antipsychotic effects in the treatment of insomnia, anxiety disorders, and psychosis, respectively. The drug is described as an atypical or "second-generation" TCA because, unlike other TCAs, it seems to be a fairly weak monoamine reuptake inhibitor. Similarly to other TCAs however, trimipramine does have antihistamine, antiserotonergic, antiadrenergic, antidopaminergic, and anticholinergic activities.
Dosulepin, also known as dothiepin and sold under the brand name Prothiaden among others, is a tricyclic antidepressant (TCA) which is used in the treatment of depression. Dosulepin was once the most frequently prescribed antidepressant in the United Kingdom, but it is no longer widely used due to its relatively high toxicity in overdose without therapeutic advantages over other TCAs. It acts as a serotonin–norepinephrine reuptake inhibitor (SNRI) and also has other activities including antihistamine, antiadrenergic, antiserotonergic, anticholinergic, and sodium channel-blocking effects.
Mianserin, sold under the brand name Tolvon among others, is an atypical antidepressant that is used primarily in the treatment of depression in Europe and elsewhere in the world. It is a tetracyclic antidepressant (TeCA). Mianserin is closely related to mirtazapine, both chemically and in terms of its actions and effects, although there are significant differences between the two drugs.
Opipramol, sold under the brand name Insidon among others, is an anxiolytic and tricyclic antidepressant that is used throughout Europe. Despite chemically being a tricyclic dibenzazepine (iminostilbene) derivative similar to imipramine, opipramol is not a monoamine reuptake inhibitor like most other tricyclic antidepressants, and instead, uniquely among antidepressants, acts primarily as a SIGMAR1 agonist. It was developed by Schindler and Blattner in 1961.
A serotonin receptor agonist is an agonist of one or more serotonin receptors. They activate serotonin receptors in a manner similar to that of serotonin, a neurotransmitter and hormone and the endogenous ligand of the serotonin receptors.
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