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Pharmacologic class: Piperazine phenothiazine
Therapeutic class: Antipsychotic
Pregnancy risk category C
Unknown. Thought to act on subcortical levels of hypothalamic and limbic systems by producing antidopaminergic effects. Also lowers seizure threshold and exhibits some adrenergic, muscarinic, and anticholinergic activity.
Tablets: 1 mg, 2 mg, 5 mg, 10 mg
Indications and dosages
Adults: 2 to 5 mg P.O. b.i.d.; may increase gradually to obtain adequate response. Usual maintenance dosage is 15 to 20 mg/day.
Children ages 6 to 12: Initially, 1 mg P.O. once or twice daily in hospitalized patients or those under close supervision; may increase gradually up to 15 mg/day P.O. until symptoms are controlled or adverse reactions are intolerable.
➣ Nonpsychotic anxiety
Adults: 1 to 2 mg P.O. b.i.d. Do not exceed 6 mg/day or 12 weeks' duration.
• Hepatic disease
• Elderly or debilitated patients
• Hypersensitivity to drug, other phenothiazines, or bisulfites
• Severe hepatic disease
• Bone marrow depression
• Blood dyscrasias
• Concomitant use of other CNS depressants in high doses
Use cautiously in:
• seizure disorders, cardiovascular disorders, GI obstruction, glaucoma, retinopathy
• elderly or debilitated patients
• pregnant or breastfeeding patients.
• Be aware that dosage should be adjusted to needs of individual. Lowest effective dosage should always be used.
CNS: sedation, dizziness, drowsiness, insomnia, fatigue, extrapyramidal effects, tardive dyskinesia, neuroleptic malignant syndrome (NMS)
CV: tachycardia, hypotension, orthostatic hypotension, peripheral edema, prolonged QT interval, torsades de pointes
EENT: dry eyes, blurred vision, miosis, mydriasis, epithelial keratopathy, pigmentary retinopathy
GI: constipation, biliary stasis, dry mouth, anorexia, adynamic ileus
GU: urinary retention, glycosuria, amenorrhea, ejaculatory disorders, galactorrhea, gynecomastia
Hematologic: leukopenia, agranulocytosis
Hepatic: cholestatic jaundice
Musculoskeletal: muscle weakness
Skin: photosensitivity, altered pigmentation, erythema, rash
Other: mild fever, weight gain, allergic reaction
Drug-drug. Alpha-adrenergic blockers: additive effect
Antacids containing aluminum: decreased trifluoperazine absorption
Anticholinergics, anticholinergic-like drugs (including antidepressants, antihistamines, disopyramide, other phenothiazines, quinidine): additive anticholinergic effects
Anticonvulsants: decreased seizure threshold
Antihistamines, CNS depressants, general anesthetics, opioids, sedative-hypnotics: additive CNS depression
Barbiturates: decreased blood levels of both drugs
Guanethidine: decreased antihypertensive effect
Lithium: increased risk of extrapyramidal reactions, disorientation, and unconsciousness
Oral anticoagulants: decreased anticoagulant effect
Phenytoin: interference with phenytoin metabolism, causing phenytoin toxicity
Propranolol: increased blood levels of both drugs
Thiazide diuretics: additive orthostatic hypotension
Drug-diagnostic tests. Hepatic enzymes: increased levels
Phenylketonuria test: false-positive result
Prolactin: increased level, causing interference with gonadotropin tests
Urine bilirubin: false-positive result
Drug-herbs. St. John's wort: increased risk of photosensitivity
Drug-behaviors. Alcohol use: additive CNS depression and hypotension
Sun exposure: increased risk of photosensitivity
• Monitor ECG and blood pressure. Watch closely for hypotension.
• Assess CBC (including platelet count) and liver function tests. Stay alert for signs and symptoms of hepatic damage and blood dyscrasias.
☞ Monitor neurologic status, especially for indications of NMS (unstable blood pressure, high fever, sweating, stupor, muscle rigidity, and autonomic dysfunction). Immediately discontinue drug if these symptoms occur.
• If signs and symptoms of tardive dyskinesia appear (repetitive, involuntary, purposeless movements, such as grimacing, tongue protrusion, lip smacking, and rapid eye blinking), consider discontinuing drug. However, some patients may require treatment despite presence of the syndrome.
• Tell patient that drug's full effect usually occurs in 1 to 2 weeks.
• Instruct patient to move slowly when sitting up or standing, to avoid dizziness from sudden blood pressure drop.
☞ Teach patient to recognize and immediately report signs and symptoms of NMS and tardive dyskinesia.
• Caution patient to avoid driving and other hazardous activities until he knows how drug affects him.
• Tell patient to avoid alcohol and certain herbs.
• Advise patient to avoid sun exposure and to wear sunscreen and protective clothing when going outdoors.
• 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.