The Utilization of Quetiapine in the Treatment of Bipolar Disorder

Quetiapine, also known for the trade name Seroquel and chemical name 2-[2-(4-dibenzo [b,f] [1,4]thiazepin-11-yl-1-piperazinyl)ethoxy]-ethanol fumarate, is an atypical antipsychotic, currently prescribed as a form of treatment for schizophrenia, bipolar disorder and depression. Quetiapine originally became available for treatment in 1997 in the United States and is still presently used as a form of first-line treatment (Riedel, Muller, Strassnig, Spellman, Severus, & Moller, 2007).

For patients of bipolar disorder, Quetiapine has established efficacy in the treatment of acute mania and depression. Specifically, Quetiapine has been utilized as both a monotherapy and an adjunctive therapy for adults and adolescents with bipolar disorder (Dando & Keating, 2005). While the pathophysiology of bipolar disorder is quite ambiguous, the disorder is known for strong heritability, which has led to large bodies of research surrounding the genetic profile of the disorder. Specifically, the monoamine hypothesis and the hypothesis of low serotonergic function are cited as potential causes of depressive and manic episodes (Newberg, Catapano, Zarate, & Manji, 2008). The hypothesis states that abnormalities of the noradrenergic, dopaminergic, and serotonergic systems are present in bipolar disorder. In the pharmacological treatment of bipolar disorder, the dopamine D2 receptor is commonly blocked, in order to regulate dopaminergic systems. (Newberg et al., 2008). There is additional evidence of low levels of plasma in the GABAergic system and elevated levels in the Glutamatergic system. The pathophysiology of bipolar disorder is also evidently connected to intracellular cascades, and specifically, reductions of volume in the dorsolateral prefrontal cortex and low glial cell density (Newberg et al., 2008).

Quetiapine, in the treatment of bipolar disorder, is an antagonist of serotonin, dopamine, histamine, and norepinephrine. While the precise mechanism of action of quetiapine is unknown, the drug inhibits 5HT1A, 5HT2A, D1, D2, alpha 1, and alpha 2 receptors (Dando &Keating, 2005). Quetiapine is taken orally, and is mainly metabolized in the liver. The drug reaches steady-state plasma levels within two days of dosage, and the half-life is close to 6 hours. The drug is usually administered twice daily with an effective dosage of 400 to 800 milligrams per day (Dando & Keating, 2005). Quetiapine is well tolerated, however, patients may experience side effects such as weight gain, dry mouth, dizziness, sedation, constipation, vomiting, or headache. Quetiapine is highly efficacious in the reduction of manic and depressive symptoms in patients of Bipolar Disorder (Dando & Keating, 2005).

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