A syndrome of potentially irreversible, involuntary, dyskinetic movements may develop in patients treated with antipsychotic drugs, including quetiapine. Although the prevalence of the syndrome appears to be highest among the elderly, especially elderly women, it is impossible to rely upon prevalence estimates to predict, at the inception of antipsychotic treatment, which patients are likely to develop the syndrome. Whether antipsychotic drug products differ in their potential to cause tardive dyskinesia is unknown.
The risk of developing tardive dyskinesia and the likelihood that it will become irreversible are believed to increase as the duration of treatment and the total cumulative dose of antipsychotic drugs administered to the patient increase. However, the syndrome can develop, although much less commonly, after relatively brief treatment periods at low doses or may even arise after discontinuation of treatment.
There is no known treatment for established cases of tardive dyskinesia, although the syndrome may remit, partially or completely, if antipsychotic treatment is withdrawn. Antipsychotic treatment, itself, however, may suppress (or partially suppress) the signs and symptoms of the syndrome and thereby may possibly mask the underlying process. The effect that symptomatic suppression has upon the long-term course of the syndrome is unknown.
Given these considerations, quetiapine fumarate should be prescribed in a manner that is most likely to minimize the occurrence of tardive dyskinesia. Chronic antipsychotic treatment should generally be reserved for patients who appear to suffer from a chronic illness that (1) is known to respond to antipsychotic drugs, and (2) for whom alternative, equally effective, but potentially less harmful treatments are not available or appropriate. In patients who do require chronic treatment, the smallest dose and the shortest duration of treatment producing a satisfactory clinical response should be sought. The need for continued treatment should be reassessed periodically.
If signs and symptoms of tardive dyskinesia appear in a patient on quetiapine fumarate, drug discontinuation should be considered. However, some patients may require treatment with quetiapine fumarate despite the presence of the syndrome.
Quetiapine may induce orthostatic hypotension associated with dizziness, tachycardia and, in some patients, syncope, especially during the initial dose-titration period, probably reflecting its α1-adrenergic antagonist properties. Syncope was reported in 1% (28/3265) of the patients treated with quetiapine fumarate, compared with 0.2% (2/954) on placebo and about 0.4% (2/527) on active control drugs. Orthostatic hypotension, dizziness, and syncope may lead to falls.
Quetiapine fumarate should be used with particular caution in patients with known cardiovascular disease (history of myocardial infarction or ischemic heart disease, heart failure or conduction abnormalities), cerebrovascular disease or conditions which would predispose patients to hypotension (dehydration, hypovolemia and treatment with antihypertensive medications). The risk of orthostatic hypotension and syncope may be minimized by limiting the initial dose to 25 mg twice daily [see Dosage and Administration (2.2)]. If hypotension occurs during titration to the target dose, a return to the previous dose in the titration schedule is appropriate.
Atypical antipsychotic drugs, including quetiapine fumarate, may cause somnolence, postural hypotension, motor and sensory instability, which may lead to falls and, consequently, fractures or other injuries. For patients with diseases, conditions, or medications that could exacerbate these effects, complete fall risk assessments when initiating antipsychotic treatment and recurrently for patients on long-term antipsychotic therapy.
In placebo-controlled trials in children and adolescents with schizophrenia (6-week duration) or bipolar mania (3-week duration), the incidence of increases at any time in systolic blood pressure (≥20 mmHg) was 15.2% (51/335) for quetiapine fumarate and 5.5% (9/163) for placebo; the incidence of increases at any time in diastolic blood pressure (≥10 mmHg) was 40.6% (136/335) for quetiapine fumarate and 24.5% (40/163) for placebo. In the 26-week open-label clinical trial, one child with a reported history of hypertension experienced a hypertensive crisis. Blood pressure in children and adolescents should be measured at the beginning of, and periodically during treatment.
In a placebo-controlled quetiapine fumarate extended-release tablets clinical trial (8 weeks duration) in children and adolescents (10 to 17 years of age) with bipolar depression, in which efficacy was not established, the incidence of increases at any time in systolic blood pressure (≥20 mmHg) was 6.5% (6/92) for quetiapine fumarate extended-release tablets and 6% (6/100) for placebo; the incidence of increases at any time in diastolic blood pressure (≥10 mmHg) was 46.7% (43/92) for quetiapine fumarate extended-release tablets and 36% (36/100) for placebo.
In clinical trial and postmarketing experience, events of leukopenia/neutropenia have been reported temporally related to atypical antipsychotic agents, including quetiapine fumarate. Agranulocytosis (including fatal cases) has also been reported.
Possible risk factors for leukopenia/neutropenia include pre-existing low white cell count (WBC) and history of drug-induced leukopenia/neutropenia. Patients with a pre-existing low WBC or a history of drug induced leukopenia/neutropenia should have their complete blood count (CBC) monitored frequently during the first few months of therapy and should discontinue quetiapine fumarate at the first sign of a decline in WBC in absence of other causative factors.
Patients with neutropenia should be carefully monitored for fever or other symptoms or signs of infection and treated promptly if such symptoms or signs occur. Patients with severe neutropenia (absolute neutrophil count <1000/mm3) should discontinue quetiapine fumarate and have their WBC followed until recovery.
The development of cataracts was observed in association with quetiapine treatment in chronic dog studies [see Nonclinical Toxicology (13.2)]. Lens changes have also been observed in adults, children and adolescents during long-term quetiapine fumarate treatment, but a causal relationship to quetiapine fumarate use has not been established. Nevertheless, the possibility of lenticular changes cannot be excluded at this time. Therefore, examination of the lens by methods adequate to detect cataract formation, such as slit lamp exam or other appropriately sensitive methods, is recommended at initiation of treatment or shortly thereafter, and at 6-month intervals during chronic treatment.
In clinical trials, quetiapine was not associated with a persistent increase in QT intervals. However, the QT effect was not systematically evaluated in a thorough QT study. In post marketing experience, there were cases reported of QT prolongation in patients who overdosed on quetiapine [see Overdosage (10.1)] , in patients with concomitant illness, and in patients taking medicines known to cause electrolyte imbalance or increase QT interval [see Drug Interactions (7.1)].
The use of quetiapine should be avoided in combination with other drugs that are known to prolong QTc including Class 1A antiarrythmics (e.g., quinidine, procainamide) or Class III antiarrythmics (e.g., amiodarone, sotalol), antipsychotic medications (e.g., ziprasidone, chlorpromazine, thioridazine), antibiotics (e.g., gatifloxacin, moxifloxacin), or any other class of medications known to prolong the QTc interval (e.g., pentamidine, levomethadyl acetate, methadone).
Quetiapine should also be avoided in circumstances that may increase the risk of occurrence of torsade de pointes and/or sudden death including (1) a history of cardiac arrhythmias such as bradycardia; (2) hypokalemia or hypomagnesemia; (3) concomitant use of other drugs that prolong the QTc interval; and (4) presence of congenital prolongation of the QT interval.
Caution should also be exercised when quetiapine is prescribed in patients with increased risk of QT prolongation (e.g., cardiovascular disease, family history of QT prolongation, the elderly, congestive heart failure and heart hypertrophy).
During clinical trials, seizures occurred in 0.5% (20/3490) of patients treated with quetiapine fumarate compared to 0.2% (2/954) on placebo and 0.7% (4/527) on active control drugs. As with other antipsychotics, quetiapine fumarate should be used cautiously in patients with a history of seizures or with conditions that potentially lower the seizure threshold, e.g., Alzheimer’s dementia. Conditions that lower the seizure threshold may be more prevalent in a population of 65 years or older.
Adults: Clinical trials with quetiapine demonstrated dose-related decreases in thyroid hormone levels. The reduction in total and free thyroxine (T4 ) of approximately 20% at the higher end of the therapeutic dose range was maximal in the first six weeks of treatment and maintained without adaptation or progression during more chronic therapy. In nearly all cases, cessation of quetiapine treatment was associated with a reversal of the effects on total and free T4 , irrespective of the duration of treatment. The mechanism by which quetiapine effects the thyroid axis is unclear. If there is an effect on the hypothalamic-pituitary axis, measurement of TSH alone may not accurately reflect a patient’s thyroid status. Therefore, both TSH and free T4 , in addition to clinical assessment, should be measured at baseline and at follow-up.
In the mania adjunct studies, where quetiapine fumarate was added to lithium or divalproex, 12% (24/196) of quetiapine fumarate treated patients compared to 7% (15/203) of placebo-treated patients had elevated TSH levels. Of the quetiapine fumarate treated patients with elevated TSH levels, 3 had simultaneous low free T4 levels (free T4 <0.8 LLN).
About 0.7% (26/3489) of quetiapine fumarate patients did experience TSH increases in monotherapy studies. Some patients with TSH increases needed replacement thyroid treatment.
In all quetiapine trials, the incidence of significant shifts in thyroid hormones and TSH were1: decrease in free T4 (free T4 <0.8 LLN), 2% (357/17513); decrease in total T4 , 4% (75/1861); decrease in free T3 , 0.4% (53/13766); decrease in total T3 , 2% (26/1312), and increase in TSH, 4.9% (956/19412). In eight patients, where TBG was measured, levels of TBG were unchanged.
Table 8 shows the incidence of these shifts in short-term placebo-controlled clinical trials.
Table 8: Incidence of Shifts in Thyroid Hormone Levels and TSH in Short-Term Placebo-Controlled Clinical Trials1,2
|Total T4||Free T4||Total T3||Free T3||TSH|
1 Based on shifts from normal baseline to potentially clinically important value at any time post-baseline. Shifts in total T4 , free T4 , total T3 and free T3 are defined as <0.8 x LLN (pmol/L) and shift in TSH is >5 mlU/L at any time.
2 Includes quetiapine fumarate and quetiapine fumarate extended-release tablets data.
In short-term placebo-controlled monotherapy trials, the incidence of reciprocal, shifts in T3 and TSH was 0% for both quetiapine (1/4800) and placebo (0/2190) and for T4 and TSH the shifts were 0.1% (7/6154) for quetiapine versus 0% (1/3007) for placebo.
Children and Adolescents:
In acute placebo-controlled trials in children and adolescent patients with schizophrenia (6-week duration) or bipolar mania (3-week duration), the incidence of shifts for thyroid function values at any time for quetiapine fumarate treated patients and placebo-treated patients for elevated TSH was 2.9% (8/280) vs. 0.7% (1/138), respectively and for decreased total thyroxine was 2.8% (8/289) vs. 0% (0/145, respectively). Of the quetiapine fumarate treated patients with elevated TSH levels, 1 had simultaneous low free T4 level at end of treatment.
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