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ALERT: U.S. Boxed Warning
The FDA-approved labeling includes a boxed warning. See Warnings/Precautions section for a concise summary of this information. For verbatim wording of the boxed warning, consult the product labeling or www.fda.gov.
Pronunciation
(thye oh RID a zeen)
Generic Available (U.S.)
Yes
Index Terms
Pharmacologic Category
Pharmacologic Category Synonyms
Use: Labeled Indications
Management of schizophrenic patients who fail to respond adequately to treatment with other antipsychotic drugs, either because of insufficient effectiveness or the inability to achieve an effective dose due to intolerable adverse effects from those medications
Use: Unlabeled
Behavior problems (children); severe psychoses (children); schizophrenia/psychoses (children); depressive disorders/dementia (children and adults); behavioral symptoms associated with dementia (elderly); psychosis/agitation related to Alzheimer's dementia
Pregnancy Risk Factor
C
Pregnancy Considerations
Jaundice or hyper-/hyporeflexia have been reported in newborn infants following maternal use of phenothiazines. Antipsychotic use during the third trimester of pregnancy has a risk for abnormal muscle movements (extrapyramidal symptoms [EPS]) and withdrawal symptoms in newborns following delivery. Symptoms in the newborn may include agitation, feeding disorder, hypertonia, hypotonia, respiratory distress, somnolence, and tremor; these effects may be self-limiting or require hospitalization.
Breast-Feeding Considerations
Other phenothiazines are excreted in human milk; excretion of thioridazine is not known.
Contraindications
Severe CNS depression; severe hyper-/hypotensive heart disease; coma; in combination with other drugs that are known to prolong the QTc interval and/or CYP2D6 inhibitors; in patients with congenital long QT syndrome or a history of cardiac arrhythmias; concurrent use with medications that inhibit the metabolism of thioridazine (fluoxetine, paroxetine, fluvoxamine, propranolol, pindolol); patients known to have genetic defect leading to reduced levels of activity of CYP2D6
Warnings/Precautions
Boxed warnings:
• Arrhythmias: See “Concerns related to adverse effects” below.
• Dementia: See “Disease-related concerns” below.
Concerns related to adverse effects:
• Arrhythmias: [U.S. Boxed Warning]: Has dose-related effects on ventricular repolarization leading to QTc prolongation, a potentially life-threatening effect. Therefore, it should be reserved for patients with schizophrenia who have failed to respond to adequate levels of other antipsychotic drugs.
• Anticholinergic effects: May cause anticholinergic effects (constipation, xerostomia, blurred vision, urinary retention); use with caution in patients with decreased gastrointestinal motility, paralytic ileus, urinary retention, BPH, xerostomia, or visual problems. Relative to other neuroleptics, thioridazine has a high potency of cholinergic blockade.
• Blood dyscrasias: Leukopenia, neutropenia, and agranulocytosis (sometimes fatal) have been reported in clinical trials and postmarketing reports with antipsychotic use; presence of risk factors (eg, pre-existing low WBC or history of drug-induced leuko-/neutropenia) should prompt periodic blood count assessment. Discontinue therapy at first signs of blood dyscrasias or if absolute neutrophil count <1000/mm3.
• Esophageal dysmotility/aspiration: Antipsychotic use has been associated with esophageal dysmotility and aspiration; use with caution in patients at risk of pneumonia (ie, Alzheimer's disease).
• Extrapyramidal symptoms (EPS): May cause extrapyramidal symptoms, including pseudoparkinsonism, acute dystonic reactions, akathisia, and tardive dyskinesia. Risk of dystonia (and possibly other EPS) may be greater with increased doses, use of conventional antipsychotics, males, and younger patients.
• Hyperprolactinemia: Use associated with increased prolactin levels; clinical significance of hyperprolactinemia in patients with breast cancer or other prolactin-dependent tumors is unknown.
• Neuroleptic malignant syndrome (NMS): May be associated with NMS; monitor for mental status changes, fever, muscle rigidity, and/or autonomic instability.
• Ocular effects: May cause pigmentary retinopathy, and lenticular and corneal deposits, particularly with prolonged therapy.
• Orthostatic hypotension: May cause orthostatic hypotension; use with caution in patients at risk of this effect or in those who would not tolerate transient hypotensive episodes (cerebrovascular disease, cardiovascular disease, hypovolemia, or concurrent medication use which may predispose to hypotension/bradycardia).
• Sedation: Highly sedating which may impair physical or mental abilities; patients must be cautioned about performing tasks which require mental alertness (eg, operating machinery or driving).
• Temperature regulation: Impaired core body temperature regulation may occur; caution with strenuous exercise, heat exposure, dehydration, and concomitant medication possessing anticholinergic effects.
Disease-related concerns:
• Cardiovascular disease: Use with caution in patients with severe cardiovascular disease.
• Dementia: [U.S. Boxed Warning]: Elderly patients with dementia-related psychosis treated with antipsychotics are at an increased risk of death compared to placebo. Most deaths appeared to be either cardiovascular (eg, heart failure, sudden death) or infectious (eg, pneumonia) in nature. Thioridazine is not approved for the treatment of dementia-related psychosis.
• Glaucoma: Use with caution in patients with narrow-angle glaucoma; condition may be exacerbated by cholinergic blockade.
• Hepatic impairment: Use with caution in patients with hepatic impairment.
• Myasthenia gravis: Use with caution in patients with myasthenia gravis; condition may be exacerbated by cholinergic blockade.
• Parkinson's disease: Use with caution in patients with Parkinson's disease.
• Renal impairment: Use with caution in patients with renal impairment.
• Seizure disorder: Use with caution in patients at risk of seizures, including those with a history of seizures, head trauma, brain damage, alcoholism, or concurrent therapy with medications which may lower seizure threshold.
Concurrent drug therapy issues:
• Antiemetic effects: May mask toxicity of other drugs or conditions (eg, intestinal obstruction, Reye's syndrome, brain tumor) due to antiemetic effects.
• High potential for interactions: Due to potential for QTc prolongation; use contraindicated with concomitant CYP2D6 inhibitors and/or concomitant use with other agents that prolong the QTc interval.
• Sedatives: Effects may be potentiated when used with other sedative drugs or ethanol.
Special populations:
• Elderly: May be inappropriate for use in this age group due to risk of CNS and EPS adverse effects (Beers Criteria).
Adverse Reactions
Frequency not defined.
Cardiovascular: ECG changes, hypotension, orthostatic hypotension, peripheral edema
Central nervous system: Akathisia, dizziness, drowsiness; EPS (pseudoparkinsonism, akathisia, dystonias, tardive dyskinesia); impairment of temperature regulation, lowering of seizure threshold, neuroleptic malignant syndrome (NMS), seizure
Dermatologic: Increased sensitivity to sun, rash, discoloration of skin (blue-gray)
Endocrine & metabolic: Amenorrhea, breast pain, galactorrhea, libido (changes in), menstrual cycle (changes in)
Gastrointestinal: Constipation, diarrhea, nausea, stomach pain, vomiting, weight gain, xerostomia
Genitourinary: Difficulty in urination, ejaculatory disturbances, urinary retention, priapism
Hematologic: Agranulocytosis, leukopenia
Hepatic: Cholestatic jaundice, hepatotoxicity
Neuromuscular & skeletal: Tremor
Ocular: Blurred vision, cornea and lens changes, pigmentary retinopathy
Respiratory: Nasal congestion
Metabolism/Transport Effects
Substrate of CYP2C19 (minor), CYP2D6 (major); Note: Assignment of Major/Minor substrate status based on clinically relevant drug interaction potential; Inhibits CYP1A2 (weak), CYP2C9 (weak), CYP2D6 (strong), CYP2E1 (weak)
Drug Interactions
Abiraterone Acetate: May increase the serum concentration of CYP2D6 Substrates. Management: Avoid concurrent use of abiraterone with CYP2D6 substrates that have a narrow therapeutic index whenever possible. When concurrent use is not avoidable, monitor patients closely for signs/symptoms of toxicity. Risk D: Consider therapy modification
Acetylcholinesterase Inhibitors (Central): May enhance the neurotoxic (central) effect of Antipsychotics. Severe extrapyramidal symptoms have occurred in some patients. Risk C: Monitor therapy
Alcohol (Ethyl): CNS Depressants may enhance the CNS depressant effect of Alcohol (Ethyl). Risk C: Monitor therapy
Alfuzosin: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy
Amphetamines: Antipsychotics may diminish the stimulatory effect of Amphetamines. Risk C: Monitor therapy
Analgesics (Opioid): Antipsychotic Agents (Phenothiazines) may enhance the hypotensive effect of Analgesics (Opioid). Risk C: Monitor therapy
Antacids: May decrease the absorption of Antipsychotic Agents (Phenothiazines). Risk C: Monitor therapy
Anticholinergics: May enhance the adverse/toxic effect of other Anticholinergics. Exceptions: Levocabastine (Nasal); Paliperidone. Risk C: Monitor therapy
Antidepressants (Serotonin Reuptake Inhibitor/Antagonist): Antipsychotic Agents (Phenothiazines) may enhance the adverse/toxic effect of Antidepressants (Serotonin Reuptake Inhibitor/Antagonist). Specifically, this may be manifest as symptoms consistent with serotonin syndrome or neuroleptic malignant syndrome. Antidepressants (Serotonin Reuptake Inhibitor/Antagonist) may enhance the hypotensive effect of Antipsychotic Agents (Phenothiazines). Risk C: Monitor therapy
Antimalarial Agents: May increase the serum concentration of Antipsychotic Agents (Phenothiazines). Risk C: Monitor therapy
Anti-Parkinson's Agents (Dopamine Agonist): May diminish the therapeutic effect of Antipsychotics (Typical). Antipsychotics (Typical) may enhance the therapeutic effect of Anti-Parkinson's Agents (Dopamine Agonist). Management: Avoid concomitant therapy if possible and monitor for decreased effects of both agents when these combinations cannot be avoided. Atypical antipsychotics such as clozapine and quetiapine may be less likely to reduce the effects of anti-Parkinson's agents. Risk D: Consider therapy modification
Artemether: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination
Atomoxetine: CYP2D6 Inhibitors (Strong) may increase the serum concentration of Atomoxetine. Management: Initiate atomoxetine at a reduced dose (adult doses -- patients up to 70kg: 0.5mg/kg/day; patients 70kg or more: 40mg/day) in patients receiving a strong CYP2D6 inhibitor. Risk D: Consider therapy modification
Beta-Blockers: Antipsychotic Agents (Phenothiazines) may enhance the hypotensive effect of Beta-Blockers. Beta-Blockers may decrease the metabolism of Antipsychotic Agents (Phenothiazines). Antipsychotic Agents (Phenothiazines) may decrease the metabolism of Beta-Blockers. Exceptions: Atenolol; Levobunolol; Metipranolol; Nadolol. Risk C: Monitor therapy
Chloroquine: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy
Ciprofloxacin: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy
Ciprofloxacin (Systemic): May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy
CNS Depressants: May enhance the adverse/toxic effect of other CNS Depressants. Exceptions: Levocabastine (Nasal). Risk C: Monitor therapy
CYP2D6 Inhibitors: May decrease the metabolism of Thioridazine. Risk X: Avoid combination
CYP2D6 Substrates: CYP2D6 Inhibitors (Strong) may decrease the metabolism of CYP2D6 Substrates. Exceptions: Tamoxifen. Risk D: Consider therapy modification
Darunavir: May increase the serum concentration of CYP2D6 Substrates. Risk C: Monitor therapy
Dronedarone: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Dronedarone. Risk X: Avoid combination
Fesoterodine: CYP2D6 Inhibitors may increase serum concentrations of the active metabolite(s) of Fesoterodine. Risk C: Monitor therapy
FluvoxaMINE: May increase the serum concentration of Thioridazine. Risk X: Avoid combination
Gadobutrol: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk D: Consider therapy modification
HydrOXYzine: May enhance the CNS depressant effect of CNS Depressants. Risk C: Monitor therapy
Indacaterol: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk C: Monitor therapy
Lithium formulations: May enhance the neurotoxic effect of Antipsychotics. Lithium formulations may decrease the serum concentration of Antipsychotics. Specifically noted with chlorpromazine. Risk C: Monitor therapy
Lumefantrine: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination
Methylphenidate: Antipsychotics may enhance the adverse/toxic effect of Methylphenidate. Methylphenidate may enhance the adverse/toxic effect of Antipsychotics. Risk C: Monitor therapy
Metoclopramide: May enhance the adverse/toxic effect of Antipsychotics. Risk X: Avoid combination
Moclobemide: May increase the serum concentration of Thioridazine. Risk X: Avoid combination
Nilotinib: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination
Peginterferon Alfa-2b: May decrease the serum concentration of CYP2D6 Substrates. Risk C: Monitor therapy
Pimozide: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Pimozide. Risk X: Avoid combination
Porfimer: Photosensitizing Agents may enhance the photosensitizing effect of Porfimer. Risk C: Monitor therapy
Pramlintide: May enhance the anticholinergic effect of Anticholinergics. These effects are specific to the GI tract. Risk D: Consider therapy modification
QTc-Prolonging Agents: May enhance the QTc-prolonging effect of Thioridazine. Risk X: Avoid combination
QTc-Prolonging Agents: May enhance the adverse/toxic effect of other QTc-Prolonging Agents. Their effects can be additive, causing life-threatening ventricular arrhythmias. Risk D: Consider therapy modification
QUEtiapine: May enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination
Quinagolide: Antipsychotics may diminish the therapeutic effect of Quinagolide. Risk C: Monitor therapy
QuiNINE: QTc-Prolonging Agents may enhance the QTc-prolonging effect of QuiNINE. QuiNINE may enhance the QTc-prolonging effect of QTc-Prolonging Agents. Risk X: Avoid combination
Serotonin Modulators: Antipsychotics may enhance the serotonergic effect of Serotonin Modulators. This could result in serotonin syndrome. Risk C: Monitor therapy
Tamoxifen: CYP2D6 Inhibitors (Strong) may decrease the metabolism of Tamoxifen. Specifically, strong CYP2D6 inhibitors may decrease the formation of highly potent active metabolites. Risk X: Avoid combination
Tetrabenazine: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Tetrabenazine. Risk X: Avoid combination
Tetrabenazine: May enhance the adverse/toxic effect of Antipsychotics. Risk C: Monitor therapy
Toremifene: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Toremifene. The risk for potentially dangerous arrhythmias may be increased. Risk X: Avoid combination
Vandetanib: QTc-Prolonging Agents may enhance the arrhythmogenic effect of Vandetanib. Risk X: Avoid combination
Vemurafenib: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Vemurafenib. Risk X: Avoid combination
Ziprasidone: QTc-Prolonging Agents may enhance the QTc-prolonging effect of Ziprasidone. The risk of a severe arrhythmia may be increased. Risk X: Avoid combination
Ethanol/Nutrition/Herb Interactions
Ethanol: May increase CNS depression; monitor for increased effects with coadministration. Caution patients about effects.
Herb/Nutraceutical: Avoid kava kava, valerian, St John's wort, gotu kola (may increase CNS depression). Avoid dong quai, St John's wort (may also cause photosensitization).
Storage
Protect from light.
Mechanism of Action
Thioridazine is a piperidine phenothiazine which blocks postsynaptic mesolimbic dopaminergic receptors in the brain; exhibits a strong alpha-adrenergic blocking effect and depresses the release of hypothalamic and hypophyseal hormones
Pharmacodynamics/Kinetics
Duration: 4-5 days
Half-life elimination: 21-25 hours
Time to peak, serum: ~1 hour
Dosage
Oral:
Children >2-12 years (unlabeled use): Range: 0.5-3 mg/kg/day in 2-3 divided doses; usual: 1 mg/kg/day; maximum: 3 mg/kg/day
Behavior problems (unlabeled use): Initial: 10 mg 2-3 times/day, increase gradually
Severe psychoses (unlabeled use): Initial: 25 mg 2-3 times/day, increase gradually
Children >12 years (unlabeled use) and Adults:
Schizophrenia/psychoses: Initial: 50-100 mg 3 times/day with gradual increments as needed and tolerated; maximum: 800 mg/day in 2-4 divided doses
Depressive disorders/dementia (unlabeled use): Initial: 25 mg 3 times/day; maintenance dose: 20-200 mg/day
Elderly: Behavioral symptoms associated with dementia (unlabeled use): Oral: Initial: 10-25 mg 1-2 times/day; increase at 4- to 7-day intervals by 10-25 mg/day; increase dose intervals (once daily, twice daily, etc) as necessary to control response or side effects. Maximum daily dose: 400 mg; gradual increases (titration) may prevent some side effects or decrease their severity.
Hemodialysis: Not dialyzable (0% to 5%)
Administration: Oral
Do not take antacid within 2 hours of taking drug.
Monitoring Parameters
Baseline and periodic ECG; vital signs; serum potassium, lipid profile, fasting blood glucose and Hgb A1c; BMI; mental status, abnormal involuntary movement scale (AIMS); periodic eye exam; do not initiate if QTc >450 msec
Reference Range
Toxic: >1 mg/mL; lethal: 2-8 mg/dL
Test Interactions
False-positives for phenylketonuria, urinary amylase, uroporphyrins, urobilinogen; may interfere with urine detection of methadone and PCP (false-positives)
Patient Education
May be taken with food. Avoid alcohol. Maintain adequate hydration unless instructed to restrict fluid intake. You may experience excess drowsiness, lightheadedness, dizziness, blurred vision, nausea, vomiting, dry mouth, constipation, urinary retention, ejaculatory dysfunction (reversible), decreased perspiration, or photosensitivity. Report persistent CNS effects (eg, trembling fingers, altered gait or balance, excessive sedation, seizures, unusual movements, anxiety, confusion); chest pain, palpitations, or rapid heartbeat; severe dizziness; unresolved urinary retention; altered menstrual pattern; change in libido; swelling or pain in breasts (male or female); vision changes; skin rash or changes in color of skin (gray-blue); or worsening of condition.
Geriatric Considerations
Any changes in disease status in any organ system can result in behavior changes.
Many elderly patients receive antipsychotic medications for inappropriate nonpsychotic behavior. Before initiating antipsychotic medication, the clinician should investigate any possible reversible cause; any stress or stress from any disease can cause acute “confusion” or worsening of baseline nonpsychotic behavior. Most commonly acute changes in behavior are due to increases in drug dose or addition of new drug to regimen; fluid electrolyte loss; infections; and changes in environment.
In the treatment of agitated, demented, older adult patients, authors of meta-analysis of controlled trials of the response to the traditional antipsychotics (phenothiazines, butyrophenones) in controlling agitation have concluded that the use of neuroleptics results in a response rate of 18%. Clearly neuroleptic therapy for behavior control should be limited with frequent attempts to withdraw the agent given for behavior control.
This medication is considered to be potentially inappropriate in this patient population (Beers Criteria severity: High).
Dental Health: Effects on Dental Treatment
Key adverse event(s) related to dental treatment: Xerostomia and changes in salivation (normal salivary flow resumes upon discontinuation). Significant hypotension may occur, especially when the drug is administered parenterally; orthostatic hypotension is due to alpha-receptor blockade, the elderly are at greater risk for orthostatic hypotension.
Tardive dyskinesia; Prevalence rate may be 40% in elderly; development of the syndrome and the irreversible nature are proportional to duration and total cumulative dose over time. Extrapyramidal reactions are more common in elderly with up to 50% developing these reactions after 60 years of age. Drug-induced Parkinson's syndrome occurs often; akathisia is the most common extrapyramidal reaction in elderly.
Dental Health: Vasoconstrictor/Local Anesthetic Precautions
Most pharmacology textbooks state that in presence of phenothiazines, systemic doses of epinephrine paradoxically decrease the blood pressure. This is the so called “epinephrine reversal” phenomenon. This has never been observed when epinephrine is given by infiltration as part of the anesthesia procedure. Thioridazine is one of the drugs confirmed to prolong the QT interval and is accepted as having a risk of causing torsade de pointes. The risk of drug-induced torsade de pointes is extremely low when a single QT interval prolonging drug is prescribed. In terms of epinephrine, it is not known what effect vasoconstrictors in the local anesthetic regimen will have in patients with a known history of congenital prolonged QT interval or in patients taking any medication that prolongs the QT interval. Until more information is obtained, it is suggested that the clinician consult with the physician prior to the use of a vasoconstrictor in suspected patients, and that the vasoconstrictor (epinephrine, mepivacaine and levonordefrin [Carbocaine® 2% with Neo-Cobefrin®]) be used with caution.
Dental Comment
Thioridazine is known to prolong the QT interval. The QT interval is measured as the time and distance between the Q point of the QRS complex and the end of the T wave in the ECG tracing. After adjustment for heart rate, the QT interval is defined as prolonged if it is more than 450 msec in men and 460 msec in women. A long QT syndrome was first described in the 1950s and 60s as a congenital syndrome involving QT interval prolongation and syncope and sudden death. Some of the congenital long QT syndromes were characterized by a peculiar electrocardiographic appearance of the QRS complex involving a premature atria beat followed by a pause, then a subsequent sinus beat showing marked QT prolongation and deformity. This type of cardiac arrhythmia was originally termed “torsade de pointes” (translated from the French as “twisting of the points”). Thioridazine is considered as having a risk of causing torsade de pointes. Since it is not known what effect vasoconstrictors in the local anesthetic regimen will have in patients with a known history of congenital prolonged QT interval or in patients taking any medication that prolongs the QT interval, a medical consult is suggested.
Mental Health: Comment
Thioridazine is a low-potency antipsychotic. Older antipsychotic medications (chlorpromazine, haloperidol), which do not meet specific criteria for “atypical” antipsychotics, are often referred to as typical antipsychotics. They are associated with the troubling side effect, EPS. However, it is commonly believed that in order for a drug to treat psychosis, it must block dopamine is some manner.
Common side effects include sedation and neuroleptic effect (reduced initiative, interest in the environment, and display of emotion or affect). All typical antipsychotics are considered to be equally effective if given in equipotent doses. An inverse relationship exists between intrinsic antimuscarinic activity and propensity to cause extrapyramidal side effects. If dystonia or pseudoparkinsonism occurs, antiparkinsonian agents should be considered. If akathisia occurs, beta-blockers (eg, propranolol), benzodiazepines, or antiparkinsonian agents should be considered. Tardive dyskinesia (TD) secondary to typical antipsychotics has an estimated incidence of 3% to 5% per year for the first 5 years of treatment. After this time period, the incidence is estimated to be 2% to 3% per year. Prevalence rates are ∼15% to 20%. Female gender and age constitute risk factors for TD. Indeed, prevalence rates have been reported to be as high as 70% in elderly females. No specific treatment exists for TD, however, patients are often initiated on/switched to an atypical antipsychotic because of their lower incidence to cause TD and hopes of suppression.
Typical antipsychotics are usually only indicated for schizophrenia, but are generally effective for mania and psychosis and/or behavioral syndromes secondary to other mental conditions. Nonpsychiatric uses include Tourette's syndrome, Huntington's disease, and occasionally, intractable hiccups, pruritus, nausea, and vomiting.
These drugs are thought to exert their antipsychotic activity by blocking dopamine D2 receptors in the mesolimbic dopaminergic pathway. Side effects are often related to their ability to antagonize dopamine receptors in the nigrostriatal and tuberoinfundibular pathways.
Thioridazine has a black-box warning for prolongation of QTc interval.
Coadministration of two or more antipsychotics does not generally improve clinical response and may increase the potential for adverse effects.
In 2008, the FDA issued a warning regarding increased mortality risk with typical and atypical antipsychotic drugs when used in elderly patients with dementia-related psychosis.
Nursing: Physical Assessment/Monitoring
Review ophthalmic exam at beginning of therapy and periodically throughout. Monitor for CNS depression/level of sedation. Avoid skin contact with liquid medication; may cause contact dermatitis (wash immediately with warm, soapy water). Initiate at lower doses and taper dosage slowly when discontinuing.
Dosage Forms
Excipient information presented when available (limited, particularly for generics); consult specific product labeling.
Tablet, oral, as hydrochloride: 10 mg, 25 mg, 50 mg, 100 mg
Pricing: U.S. (www.drugstore.com)
Tablets (Thioridazine HCl)
10 mg (90): $23.99
25 mg (90): $28.99
50 mg (90): $35.99
100 mg (90): $34.99
References
Aman MG, Marks RE, Turbott SH, et al, “Clinical Effects of Methylphenidate and Thioridazine in Intellectually Subaverage Children,” J Am Acad Child Adolesc Psychiatry, 1991, 30(2):246-56.
Appell RA, Shield DE, and McGuire EJ, “Thioridazine-Induced Priapism,” Br J Urol, 1977, 49(2):160.
Baker PB, Merigian KS, Roberts JR, et al, “Hyperthermia, Hypertension, Hypertonia, and Coma in Massive Thioridazine Overdose,” Am J Emerg Med, 1988, 6(4):346-9.
Buckley NA, Whyte IM, and Dawson AH, “Cardiotoxicity More Common in Thioridazine Overdose Than With Other Neuroleptics,” J Toxicol Clin Toxicol, 1995, 33(3):199-204.
Burgess KR, Jefferis RW, and Stevenson IF, “Fatal Thioridazine Cardiotoxicity,” Med J Aust, 1979, 2(4):177-8.
Cowen TD and Meythaler JM, “Hypotensive Effects of Thioridazine in an Elderly Patient With Traumatic Brain Injury,” Brain Inj, 1994, 8(8):735-7.
Gill SS, Bronskill SE, Normand SL, et al, “Antipsychotic Drug Use and Mortality in Older Adults With Dementia,” Ann Intern Med, 2007, 146(11):775-86.
Goss JB, “Concomitant Use of Thioridazine With Risperidone,” Am J Health Syst Pharm, 1995, 52(9):1012.
Lancelin F, Kraoul L, Flatischler N, et al, “False-Positive Results in the Detection of Methadone in Urines of Patients Treated With Psychotropic Substances,” Clin Chem, 2005, 51(11):2176-7.
Long C, Crifasi J, and Maginn D, “Interference of Thioridazine in Identification of Phencyclidine,” Clin Chem, 1996, 42(11):1885-6.
Moore TA, “Schizophrenia Treatment Guidelines in the United States,” Clin Schizophr Relat Psychoses, 2011, 5(1):40-9.
Oshika T, “Ocular Adverse Effects of Neuropsychiatric Agents. Incidence and Management,” Drug Saf, 1995, 12(4):256-63.
Peabody CA, Warner MD, Whiteford HA, et al, “Neuroleptics and the Elderly,” J Am Geriatr Soc, 1987, 35(3):233-8.
Rabins PV, Blacker D, Rovner BW, et al, “Practice Guideline for the Treatment of Patients With Alzheimer's Disease and Other Dementias,” October, 2007. Available at http://www.psych.org/psych_pract/treatg/pg/prac_guide.cfm
Risse SC and Barnes R, “Pharmacologic Treatment of Agitation Associated With Dementia,” J Am Geriatr Soc, 1986, 34(5):368-76.
Saltz BL, Woerner MG, Kane JM, et al, “Prospective Study of Tardive Dyskinesia Incidence in the Elderly,” JAMA, 1991, 266(17):2402-6.
Schneeweiss S, Setoguchi S, Brookhart A, et al, “Risk of Death Associated With the Use of Conventional Versus Atypical Antipsychotic Drugs Among Elderly Patients,” CMAJ, 2007, 176(5): 627-32.
Seifert RD, “Therapeutic Drug Monitoring: Psychotropic Drugs,” J Pharm Pract, 1984, 6:403-16.
International Brand Names
Lexi-Comp.com
Last full review/revision January 2012
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