Quetiapine: Description, Mechanism of Action, and Side Effects

This article provides a description of Quetiapine, its mechanism of action, and side effects. It discusses how Quetiapine is used to treat psychological disorders such as schizophrenia and bipolar disorder.

Running head: QUETIAPINE
Quetiapine
Name of the Student
Name of the University
Author Note

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Introduction:
Quetiapine has a range of clinical activity distinct from other typical antipsychotic drugs.
Although the actual mechanism of the Quetiapine is not understood clearly because of the lack of
extensive research in this field, the active metabolite, Nor-quetiapine has shown to have a
unique in pharmacological profile with a massive therapeutic range (Mims.co.uk. 2019). The
prevalence of the schizophrenia is higher in adolescents and younger adults compared to the
other diseases and therefore, the drug is effective in treating schizophrenia and associated
disease. As discussed by Cross et al. (2015), Quetiapine has been prescribed to the adults and
adolescents of 13 to 17 years old to treat manic episodes of schizophrenia. Therefore, Quetiapine
has a unique contribution to treating a range of psychological illness. This paper will provide a
description of the drug; target of the drug, biological mechanisms of the drug, side effects of the
drug in the following paragraphs.
Discussion:
Description of the drug:
Quetiapine is an antipsychotic drug used for treating mainly schizophrenia. Quetiapine
and also human plasma metabolite Norquetiapine interacts with a broad range of
neurotransmitter to treat the psychological disorders. Chemical name is Bis[2-(2-[4-(dibenzo[b,f]
[1,4]-thiazepin-11-yl)piperazine- 1-yl] ethoxy) ethanol] fumarate. As discussed by Cross et al.
(2015), Molecular formula: C21H25N3O2S with the molecular formula of C21H25N3O2S and
molecular weight of 383.5099 (Mims.co.uk. 2019). As discussed by Brett (2015), the drug is a
weak acid with moderate pH solubility and lipophilic characteristics which may differ according
to pH. As discussed by Cross et al. (2015), it is the chemical class of benzylsoxazole derivative

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mainly used for schizophrenia, second-generation antipsychotics. It used in five strengths and
contains 50 mg, 150 mg, 200 mg, 300 mg and 400 mg of Quetiapine free base along with lactose,
magnesium oxide, povidone, macrogol, and others (Nps.org.au. 2019).
Drug target and use:
Quetiapine and its derivatives Nor-quetiapine exhibits their affinity for neurotransmitters
such as serotonin, dopamine D 1 and D2 receptors, indicating drug targets for reducing
psychological issues. The combined action of receptor antagonism with more affinity towards
serotonin and D2 are thought to contribute to the low extrapyramidal side effects and clinical
antipsychotic properties of the drug (Mims.co.uk. 2019). As discussed by Arici, Altun and
Acipayam (2018), nor-Quetiapine has higher the affinity for noradrenaline transporter,
muscarinic receptors to give rise to the antipsychotic activity.
Quetiapine is used for certain mental and mood conditions such as schizophrenia, a
major depressive disorder with sudden maniac episode, bipolar disorder, generalized anxiety,
delusional parasitosis, psychosis, obsessive-compulsive disorder, and other related psychotic
orders (Lai et al. 2016). The kinetics of the drug does not differ in men and women, which
further highlighted that the mechanisms of actions remain similar for every gender.
Biological effect:
Mechanism of action:
Quetiapine shows antipsychotic effect through showing antagonistic activity against
dopamine, especially D1 and D2 dopamine, serotonin receptors in the frontal context of the
human brain, alpha 1 and adrenoreceptors of smooth muscles. It also shows the antagonistic
effect on the histamine receptor H1 (Mims.co.uk. 2019). The antagonism at the dopamine

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receptors D 2 releases the positive symptoms whereas antagonism at serotonin receptors
facilitates the release of negative symptoms of schizophrenia (Mims.co.uk. 2019).
Pharmacodynamics:
The drug has selective monoaminergic antagonistic activity with high affinity for
specific receptors discussed before. Quetiapine has no significant affinity for receptors such as
benzodiazepine receptors. Quetiapine and it’s derivative Nor- quetiapine shows antagonism
with H1 receptors and alpha which further leads to the symptoms such as orthostatic hypotension
and drowsiness (Nps.org.au. 2019). It doesn’t show sensitivity towards dopamine receptors after
heavy administrations, it only blocks the receptors. Quetiapine has selectivity for the limbic
system where it produces depolarization blockade of the mesolimbic (Mohapatra 2016).
Therefore, in pre- clinical tests predictive of EPS, the drug shows an atypical profile of
antipsychotics.
Pharmacokinetics:
Absorption:
When Quetiapine is consumed, it is well absorbed and shows liver metabolisms. The
Quetiapine and nor Quetiapine both shows linear pharmacokinetic peaks across the prescribed
dose by doctors. The drug shows 83% of the plasma protein bindings and shows peak after 6
hours of oral administration (Leung et al. 2016).
Distribution: it bound to plasma to 83% with 10±4 L/kg
Metabolism:

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The metabolism route is hepatic metabolism with major metabolism pathways such as
sulfoxidation which occurs through cytochrome p450 3A4 as well as oxidation of terminal
alcohol to a carboxylic acid. It induces cytochrome P450 enzymes and also shows
hydroxylation of the dibenzothiazepine ring and phase II conjugation (Cross et al. 2015).
Elimination:
The elimination of the drug is through the hepatic pathway and less than 1% of the drug
was eliminated as unchanged. 73% of the drug is eliminated through the urine, whereas 20% is
through feces with the half-life of 7 to 12 hours (Cross et al. 2015).
Drug interactions and systematic effect:
Metabolism of drug decreases while combined with the warfarin and therapeutic efficacy
decreases while interactions 1,10-Phenanthroline. It shows THE risk or severity of the
hypotension when interacting with 1- -benzimidazole. The high dose of the drug shows the
symptoms of the drowsiness and tachycardia, somnolence, sleep troubles, hypotension, and
electrolyte imbalance (Mims.co.uk. 2019). The metabolism decreases for patients with hepatic
and renal impairments. The clearance of the drug decreases for the patients above 65 years. The
contraindication of Quetiapine is lactation observed in the patient.
Conclusion:
Thus, it can be concluded that to treat manic episodes of schizophrenia, and Nor-
quetiapine exhibits their affinity for neurotransmitters such as serotonin, dopamine D 1 and D2
receptors, indicating drug targets for reducing psychological issues. Quetiapine shows
antipsychotic effect by showing antagonistic activity against these receptors. Nor-quetiapine has
high the affinity for noradrenaline transporter, muscarinic receptors to give rise to the

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antipsychotic activity. Metabolism of drug decreases while combined with other drugs. The
drug bound to plasma to 83% with 10±4 L/kg and shows hepatic metabolism. The high-dose
drug shows the symptoms of the drowsiness and tachycardia, somnolence, sleep troubles,
hypotension, and electrolyte imbalance.

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References:
Arici, A., Altun, H., and Acipayam, C. 2018. Quetiapine Induced Autoimmune
Hemolytic Anemia in a Child Patient: A Case Report. Clinical Psychopharmacology and
Neuroscience, 16(4), 501.
Brett, J. 2015. Concerns about quetiapine. Australian prescriber, 38(3), 95.
Cross, A. J., Widzowski, D., Maciag, C., Zacco, A., Hudzik, T., Liu, J., … Wood, M. W.
2015. Quetiapine and its metabolite norquetiapine: translation from in vitro
pharmacology to in vivo efficacy in rodent models. British journal of
pharmacology, 173(1), 155–166. doi:10.1111/bph.13346
Lai, J., Lu, Q., Huang, T., Hu, S., and Xu, Y. 2017. Convulsive syncope related to a small
dose of quetiapine in an adolescent with bipolar disorder. Neuropsychiatric disease and
treatment, 13, 1905.
Leung, J. G., Nelson, S., Cunningham, J. L., Thompson, V. H., Bobo, W. V., Kung,
S., ... and Lapid, M. I. 2016. A single-dose crossover pharmacokinetic comparison study
of oral, rectal and topical quetiapine in healthy adults. Clinical pharmacokinetics, 55(8),
971-976.
Mims.co.uk. 2019. Quetiapine | MIMS online. Retrieved from
https://www.mims.co.uk/drugs/central-nervous-system/psychosis-mania/quetiapine

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Mohapatra, S. 2016. Successful Management of Tardive Dyskinesia with quetiapine and
clonazepam in a patient of schizophrenia with type 2 diabetes mellitus. Clinical
Psychopharmacology and Neuroscience, 14(2), 218.
Nps.org.au. 2019. The Australian Medicines Handbook. Retrieved from
https://www.nps.org.au/australian-prescriber/articles/the-australian-medicines-handbook