thioridazine hydrochloride (redirected from PMS Thioridazine)

thioridazine hydrochloride

[-rid′əzēn]

a phenothiazine antipsychotic.

indications It is prescribed in the treatment of schizophrenia when patients have failed to respond to other therapies and in the management of nonpsychotic behavioral disturbances, senility, alcohol withdrawal, and organic brain disease.

contraindications Parkinson's disease, concurrent administration of central nervous system depressants, hepatic or renal dysfunction, severe hypotension, or known hypersensitivity to this drug or to other phenothiazine medications prohibits its use.

adverse effects Among the more serious adverse effects are severe sedation, a potentially life-threatening prolongation of the QT interval, hypotension, hepatotoxicity, extrapyramidal reactions, blood dyscrasias, and hypersensitivity reactions. It should be used with caution in patients with premature ventricular contractions, breast cancer, and respiratory disorders and in patients exposed to extreme heat, cold, and pesticides or insecticides. The herb kava kava may increase the risk and severity of dystonic reactions.

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thioridazine hydrochloride

Apo-Thioridazine (CA), Novo-Ridazine (CA), PMS Thioridazine (CA)

Pharmacologic class: Phenothiazine

Therapeutic class: Antipsychotic

Pregnancy risk category C

FDA Boxed Warning

• Drug prolongs QTC interval in dose-related manner and may lead to torsades de pointes-type arrhythmias and sudden death. Reserve it for treatment of schizophrenic patients who don't respond acceptably to adequate courses of other antipsychotic drugs.

Action

Blocks dopamine receptors in CNS. Exerts strong alpha-adrenergic and anticholinergic blocking activity; also depresses cerebral cortex, hypothalamus, and limbic system.

Availability

Oral solution (concentrated): 30 mg/ml, 100 mg/ml

Oral suspension: 10 mg/5 ml, 25 mg/5 ml, 100 mg/5 ml

Tablets: 10 mg, 15 mg, 25 mg, 50 mg, 100 mg, 150 mg, 200 mg

⊘Indications and dosages

➣ Schizophrenia

Adults: Initially, 50 to 100 mg P.O. t.i.d.; may increase gradually as needed to a maintenance dosage of up to 800 mg/day

Severely disturbed, hospitalized children ages 2 to 12: Initially, 0.5 mg/kg/day P.O. in divided doses. May increase gradually as needed until optimal effects occur; maximum daily dosage is 3 mg/kg.

Dosage adjustment

• Renal or hepatic impairment
• Elderly patients

Contraindications

• Hypersensitivity to drug, its components, or other phenothiazines
• Severe CNS depression
• Severe hypertension or hypotension
• Bone marrow depression or blood dyscrasias
• Genetic defect that inhibits CYP450-2D6
• Congenital long-QT syndrome
• Prolonged QTc interval
• History of arrhythmias
• Concurrent use of other drugs that prolong the QTc interval (such as fluoxetine, paroxetine) or reduce phenothiazine clearance by other means (such as fluvoxamine, pindolol, propranolol)

Precautions

Use cautiously in:
• cardiovascular or respiratory disease, mitral insufficiency, hepatic or renal impairment, glaucoma, depression, seizure disorder, risk factors for electrolyte imbalance (such as dehydration or diuretic therapy)
• sulfite or tartrazine sensitivity (with some products)
• alcohol intolerance (with concentrate)
• elderly or debilitated patients
• pregnant or breastfeeding patients.

Administration

• Due to risk of potentially life-threatening proarrhythmic effects, know that drug is indicated only for schizophrenic patients who don't respond adequately to other antipsychotics.
• Keep liquid form away from skin to avoid contact dermatitis.
• Before starting therapy, correct hypokalemia as ordered.
• Discontinue at least 48 hours before myelography, because of seizure risk.

Route	Onset	Peak	Duration
P.O.	Unknown	Unknown	8-12 hr

Adverse reactions

CNS: sedation, extrapyramidal reactions, tardive dyskinesia, neuroleptic malignant syndrome, seizures

CV: orthostatic hypotension, tachycardia, prolonged QTc interval, arrhythmias

EENT: lens opacities, pigmentary retinopathy, dry eyes

GI: constipation, ileus, dry mouth, anorexia

GU: urinary retention, dark urine, galactorrhea, gynecomastia

Hepatic: jaundice

Hematologic: agranulocytosis, leukopenia

Skin: rash, photosensitivity reaction, pigmentation changes

Other: allergic reactions, hyperthermia

Interactions

Drug-drug. Anticholinergic and anticholinergic-like drugs (such as antihistamines, antidepressants, atropine, disopyramide, haloperidol, other phenothiazines): additive anticholinergic effects

Antihypertensives, nitrates: additive hypotension

CNS depressants (such as antihistamines, general anesthetics, opioid analgesics, sedative-hypnotics): additive CNS depression

Diuretics: increased risk of electrolyte imbalances and arrhythmias

Drugs that inhibit CYP450-2D6 (such as fluoxetine, paroxetine), prolong the QTc interval (such as arsenic trioxide, azole antifungals, floxin antibiotics, octreotide), or decrease phenothiazine clearance by other means (such as fluvoxamine, pindolol, propranolol): increased risk of life-threatening arrhythmias

Lithium: disorientation, loss of consciousness, increased risk of extrapyramidal reactions

Drug-diagnostic tests. Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase, serum bilirubin: increased levels

Granulocytes, hematocrit, hemoglobin, platelets, white blood cells: decreased levels

Pregnancy tests, urine bilirubin: false-positive results

Drug-herbs. Kava: increased risk of adverse drug reactions

Drug-behaviors. Alcohol use: additive hypotension

Patient monitoring

☞ Monitor neurologic status closely. Stay alert for signs and symptoms of neuroleptic malignant syndrome.
• Watch for tardive dyskinesia and extrapyramidal symptoms.
• Assess for urinary retention, constipation, and blurred vision.
• Monitor bilirubin level, CBC, liver function tests, and vision exams. Be aware that signs and symptoms of agranulocytosis, leukopenia, or hepatic dysfunction may warrant withdrawal.
☞ Closely monitor depressed patient for suicidal ideation.

Patient teaching

• Instruct patient to dilute concentrate with water or fruit juice and then take dose right away, with or without food.
☞ Caution patient not to stop therapy suddenly. Dosage must be tapered.
☞ Tell patient or caregiver to immediately report signs and symptoms of serious CNS reactions, including high fever, sweating, unstable blood pressure, stupor, muscle rigidity, tongue protrusion, cheek puffing, mouth puckering, chewing movements, and involuntary leg or arm movements.
• Caution patient to keep liquid form away from skin. If it contacts skin, advise him to wash it off thoroughly and immediately.
• Tell patient to report urinary retention, blurred vision, or constipation.
• Advise patient to avoid driving and other hazardous activities.
• Caution patient not to drink alcohol. Tell him that concentrate form contains alcohol.
• Teach patient effective ways to counteract photosensitivity.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, herbs, and behaviors mentioned above.