A-Z Drug Facts > Thioridazine Hydrochloride

Thioridazine Hydrochloride

Pronouncation: (THIGH-oh-RID-uh-zeen HIGH-droe-KLOR-ide)
Class: Phenothiazine derivative

Trade Names:
Thioridazine Hydrochloride
- Tablets 10 mg
- Tablets 15 mg
- Tablets 25 mg
- Tablets 50 mg
- Tablets 100 mg
- Tablets 150 mg
- Tablets 200 mg
- Oral Concentrate 30 mg/mL
- Oral Concentrate 100 mg/mL

Apo-Thioridazine (Canada)

Pharmacology

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Effects apparently caused by dopamine receptor blocking in CNS.

Indications and Usage

Management of schizophrenia.

Contraindications

Congenital QT interval prolongation; concurrent drugs that prolong the QT interval; history of cardiac arrhythmias; comatose or severely depressed states; allergy to this or any phenothiazine; presence of large amounts of other CNS depressants; severe hypotension or hypertension.

Dosage and Administration

Adults

PO Start with 50 to 100 mg 3 times daily, increasing the dose gradually in increments (max, 800 mg/day). Total daily dose ranges from 200 to 800 mg divided into 2 to 4 doses.

Children

PO Start with 0.5 mg/kg/day in divided doses, increasing the dose gradually until optimal therapeutic effect is obtained (max, 3 mg/kg/day).

Storage/Stability

Store tablets and oral concentrate at controlled room temperature (59° to 86°F).

Drug Interactions

Alcohol and other CNS depressants

May result in increased CNS depression and may precipitate extrapyramidal reaction.

Anticholinergics

May reduce therapeutic effects of thioridazine and worsen anticholinergic effects of thioridazine. May lead to tardive dyskinesia.

Barbiturate anesthetics

Frequency and severity of neuromuscular excitation and hypotension may increase.

Beta-blockers

May result in increased plasma levels of beta-blocker and thioridazine.

Drugs that prolong the QT interval (eg, cisapride), drugs that inhibit CYP2D6 (eg, fluoxetine, paroxetine)

May increase the risk of life-threatening cardiac arrhythmias, including torsades de pointes. Coadministration of these agents is contraindicated.

Drugs that reduce the Cl of thioridazine by other mechanisms (eg, fluvoxamine, propranolol, pindolol)

May elevate plasma levels of thioridazine, increasing the risk of side effects including life-threatening cardiac arrhythmias. Avoid coadministration of these agents.

Epinephrine

May antagonize effects of epinephrine.

Lithium

May cause disorientation, unconsciousness, and extrapyramidal effects.

Laboratory Test Interactions

May discolor urine pink to red-brown. False-positive pregnancy test results may occur, but are less likely to occur with serum test. Increases in protein bound iodine have been reported.

Adverse Reactions

Cardiovascular

Orthostatic hypotension; hypertension; tachycardia; bradycardia; syncope; cardiac arrest; circulatory collapse; lightheadedness; faintness; dizziness; EKG changes, including dose-related prolongation of the QTc interval.

CNS

Pseudoparkinsonism; dystonias; motor restlessness; headache; weakness; tremor; fatigue; slurring; insomnia; vertigo; seizures; tardive dyskinesia; drowsiness; paradoxical excitement; headache; confusion.

Dermatologic

Photosensitivity; skin pigmentation; dry skin; exfoliative dermatitis; urticarial rash; maculopapular hypersensitivity reaction; seborrhea; eczema.

EENT

Pigmentary retinopathy; glaucoma; photophobia; blurred vision; mydriasis; increased IOP; dry throat; nasal congestion.

GI

Dyspepsia; constipation; dry mouth; adynamic ileus; nausea; vomiting; diarrhea.

Genitourinary

Urinary hesitancy or retention; impotence; sexual dysfunction; dysmenorrhea; menstrual irregularities; uremia; breast enlargement; galactorrhea.

Hematologic

Agranulocytosis; eosinophilia; leukopenia; hemolytic anemia; thrombocytopenic purpura.

Hepatic

Jaundice; biliary stasis.

Metabolic

Decreased cholesterol.

Respiratory

Laryngospasm; respiratory depression; bronchospasm; dyspnea.

Miscellaneous

Increase in appetite and weight; polydipsia; neuroleptic malignant syndrome (NMS); allergy (including fever, laryngeal edema, angioneurotic edema, asthma); elevated prolactin levels.

Precautions

Warnings QTc prolongation is dose related. Torsades de pointes-type arrhythmias and sudden death. Reserved for use only in refractory schizophrenia that failed to show an acceptable response to adequate course of other antipsychotics.

Pregnancy

Safety not established.

Lactation

Safety not established.

Children

See Route/Dosage.

Elderly

More susceptible to effects; consider lower dose.

Special Risk Patients

Use caution in patients with CV disease or mitral insufficiency, history of glaucoma, EEG abnormalities, or seizure disorders, prior brain damage, hepatic or renal impairment, or in those exposed to extreme heat.

CNS effects

May impair mental or physical abilities, especially during first few days of therapy.

Hepatic effects

Jaundice usually occurs between second and fourth wk of treatment; considered hypersensitivity reaction. Usually reversible.

NMS

Has occurred with agents of this class; is potentially fatal. Signs and symptoms are hyperpyrexia, muscle rigidity, altered mental status, irregular pulse, irregular BP, tachycardia, and diaphoresis.

Pulmonary

Cases of bronchopneumonia (some fatal) occurred.

Sudden death

Sudden death reported; predisposing factors may be seizures or previous brain damage. Flare-ups of psychotic behavior may precede death.

Tardive dyskinesia

Syndrome of potentially irreversible involuntary body and facial movements may develop. Prevalence highest in the elderly, especially women. Use smallest effective doses for shortest possible time.

Overdosage

Symptoms

Decreased consciousness, arrhythmias, extrapyramidal effects, confusion, agitation, respiratory depression, anticholinergic effects.

Patient Information

• Advise patient, family, or caregiver that dose will be adjusted periodically until max benefit has been obtained.
• Advise patient, family, or caregiver not to change the dose or stop taking unless advised by health care provider.
• Instruct patient, family, or caregiver to measure prescribed dose of oral concentrate using calibrated dropper supplied with medication.
• Advise patient, family, or caregiver that oral concentrate may be diluted with 1 to 2 oz of distilled water, acidified tap water, or tomato or fruit juice just prior to administration. Caution patient, family, or caregiver to not prepare dilutions ahead of time and store.
• Instruct patient not to stop taking thioridazine when feeling better.
• Instruct patient, family, or caregiver to immediately report fainting or loss of consciousness, palpitations, dizziness, high fever, muscle rigidity, altered mental status, irregular pulse, sore throat, unusual bruising, or yellowing of the skin or eyes.
• Advise patient, family, or caregiver to notify health care provider of the following: excessive drowsiness, increased agitation or anxiety, involuntary body or facial movements, vision problems (eg, fuzzy vision, brownish coloring, impairment of night vision).
• Advise patient to avoid strenuous activity during periods of high temperature or humidity.
• Instruct patient to avoid alcoholic beverages and other depressants while taking this medication.
• Instruct patient to get up slowly from lying or sitting position and to avoid sudden position changes to prevent postural hypotension. Advise patient to report dizziness with position changes to health care provider. Caution patient that hot tubs and hot showers or baths may make dizziness worse.
• Advise patient to take sips of water, suck on ice chips or sugarless hard candy, or chew sugarless gum if dry mouth occurs.
• Advise patient that drug may cause drowsiness or impaired judgment or thinking skills and to use caution while driving or performing other tasks requiring mental alertness until tolerance is determined.
• Caution patient that medication may cause sensitivity to sunlight and to avoid unnecessary exposure to UV light (eg, sunlight, tanning booths) and to use sunscreen and wear protective clothing when exposed to UV light until tolerance is determined.

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