THIORIDAZINE HYDROCHLORIDE
(thye-or-rid'a-zeen)
Mellaril, Novoridazine 
Classifications: central nervous system agent; psychotherapeutic; phenothiazine antipsychotic
Prototype: Chlorpromazine
Pregnancy Category: C
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10 mg, 15 mg, 25 mg, 50 mg, 100 mg, 150 mg, 200 mg tablets; 30 mg/mL, 100 mg/mL solution; 25 mg/5 mL suspension
Phenothiazine similar to chlorpromazine. Rarely produces extrapyramidal effects. Has weak antiemetic but strong anticholinergic
and alpha-adrenergic agonist activity and potent sedative action.
Effective in reducing excitement, hypermotility, abnormal initiative, affective tension, and agitation by inhibiting psychomotor
functions. Also effective as an antipsychotic agent, and for behavioral disorders in children.
Management of nonpsychotic behavioral disturbances of senility, manifestations of psychotic disorders, alcohol withdrawal;
symptomatic treatment of organic brain disease. Short-term treatment of moderate to marked depression and for management of
hyperkinetic behavior syndrome (attention deficit disorder).
Hypersensitivity to phenothiazines. Severe CNS depression; CV disease; children <2 y. Safety during pregnancy (category C)
or lactation is not established.
Premature ventricular contractions; previously diagnosed breast cancer; patients exposed to extremes in heat or to organophosphorus
insecticides; respiratory disorders.
Psychotic Disorders
Adult: PO 50–100 mg t.i.d., may increase up to 800 mg/d as needed or tolerated
Geriatric: PO 10 mg t.i.d., may increase up to 200 mg/d
Child: PO >2 y, 0.5–3 mg/kg/d in divided doses; if hospitalized, may start at 25 mg t.i.d.
Moderate to Marked Depression
Adult: PO 25 mg t.i.d., may increase up to 200 mg/d in divided doses
Dementia Behavior
Geriatric: PO 10–25 mg 1–2 times/d, may increase q4–7d (max: 400 mg/d in divided doses)
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Oral
- Give with fluid of patient's choice; tablet may be crushed.
- Schedule phenothiazine at least 1 h before or 1 h after an antacid or antidiarrheal medication.
- Dilute liquid concentrate just prior to administration with ½ glass of fruit juice, milk, water, carbonated beverage, or soup.
- Add increases in dose to the first dose of the day to prevent sleep disturbance.
- Store at 15°–30° C (59°–86° F) in tightly covered, light-resistant containers unless otherwise
indicated.
CNS:
Sedation, dizziness, drowsiness, lethargy, extrapyramidal syndrome, nocturnal confusion, hyperactivity. Special Senses: Nasal congestion, blurred vision, pigmentary retinopathy. GI: Xerostomia, constipation,
paralytic ileus. Urogenital: Amenorrhea, breast engorgement, gynecomastia, galactorrhea, urinary retention. CV: Ventricular dysrhythmias, hypotension, prolonged QTc interval.
Drug:
Alcohol,
anxiolytics, sedative-hypnotics, other cns depressants add to CNS depression; additive adverse effects with other phenothiazines; amiodarone,
amoxapine,
arsenic trioxide,
bepridil,
clarithromycin,
daunorubicin,
diltiazem,
disopyramide,
dofetilide,
dolasetron,
doxorubicin,
encainide,
erythromycin,
flecainide,
fluoxetine,
fluvoxamine gatifloxacin,
grepafloxacin,
haloperidol,
ibutilide,
indapamide,
local anesthetics,
maprotiline,
moxifloxacin,
octreotide,
paroxetine,
pentamidine,
pimozide,
procainamide,
probucol,
quinidine,
risperidone,
sotalol,
sertraline,
sparfloxacin,
terodiline,
tocainide,
tricyclic antidepressants,
venlafaxine,
verapamil,
ziprasidone can prolong QTc interval resulting in arrhythmias. Herbal:
Kava-kava may increase risk and severity of dystonic reactions.
Absorption: Well absorbed from GI tract. Onset: Days to weeks. Distribution: Crosses placenta; distributed into breast milk. Metabolism: Metabolized in liver. Elimination: Excreted in urine. Half-Life: 26–36 h.
Assessment & Drug Effects
- Orthostatic hypotension may occur in early therapy. Female patients appear to be more susceptible than males.
- Be aware that patients may be unable to adjust to extremes of temperature because drug effects heat regulatory center in the
hypothalamus. Patient may complain of being cold even at average room temperature; older adults are particularly susceptible.
- Monitor I&O ratio and bowel elimination pattern. Check for abdominal distension and pain. Encourage adequate fluid intake
as prophylaxis for constipation and xerostomia. The depressed patient may not seek help for either symptom or for urinary
retention.
- Lab tests: Obtain periodic CBC and liver function tests during therapy.
- Supervise patient closely during early course of therapy. Suicide is an inherent risk with any depressed patient and may remain
a problem until there is significant clinical improvement.
Patient & Family Education
- Exercise care not to spill drug on skin because of danger of contact dermatitis. Wash skin well in soap and water if liquid
drug is spilled.
- Take drug as prescribed and do not alter dosing regimen or stop medication without consulting physician.
- Avoid alcohol during phenothiazine therapy. Concomitant use enhances CNS depression effects.
- Be aware that marked drowsiness generally subsides with continued therapy or reduction in dosage.
- Do not drive or engage in potentially hazardous activities until response to drug is known.
- Make position changes slowly, particularly from lying down to upright posture; dangle legs a few minutes before standing.
- Vasodilation produced by hot showers or baths or by long exposure to environmental heat may accentuate hypotensive effect.
- Do not apply heating pad or hot water bottles to the body for external heat. Because of depressed conditioned avoidance behaviors,
a severe burn may result.
- Report the onset of any change in visual acuity, brownish coloring of vision, or impairment of night vision to physician.
Symptoms suggest pigmentary retinopathy (observed primarily in patients receiving extremely high doses). An ophthalmic consultation
may be indicated.
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Note: Thioridazine may color urine pink-red to reddish brown.
- Do not use any OTC drugs unless approved by the physician.
- Do not breast feed while taking this drug without consulting physician.
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Prototype drug