hydroxyzine hydrochloride
Anx, Anxanil, Apo-Hydroxyzine ◆, Atarax, Hydroxacen, Hyzine-50, Multipax ◆, Neucalm, Novo-Hydroxyzin ◆, Quiess, QYS, Vistacon, Vistazine-50

hydroxyzine pamoate
Vistaril

Available forms
Available by prescription only
hydroxyzine hydrochloride
Injection: 25 mg/ml, 50 mg/ml
Syrup: 10 mg/5 ml
Tablets: 10 mg, 25 mg, 50 mg, 100 mg
Tablets (film-coated): 10 mg, 25 mg, 50 mg
hydroxyzine pamoate
Capsules: 25 mg, 50 mg, 100 mg
Oral suspension: 25 mg/5 ml

Indications and dosages
 Anxiety, tension, hyperkinesia. Adults: 50 to 100 mg P.O. q.i.d.
Children age 6 and older: 50 to 100 mg P.O. daily in divided doses.
Children younger than age 6: 50 mg P.O. daily in divided doses.
 Preoperative and postoperative adjunctive sedation, to control emesis, adjunct to asthma treatment. Adults: 25 to 100 mg I.M. q 4 to 6 hours.
Children: 1.1 mg/kg I.M. q 4 to 6 hours.
 Pruritus. Adults: 25 mg P.O. t.i.d. or q.i.d.
Children age 6 and older: 50 to 100 mg P.O. daily in divided doses.
Children younger than age 6: 50 mg P.O. daily in divided doses.

Pharmacodynamics
Anxiolytic and sedative actions: Hydroxyzine produces its sedative and antianxiety effects through suppression of activity at subcortical levels; analgesia occurs at high doses.
Antipruritic action: Drug is a direct competitor of histamine for binding at cellular receptor sites.
Other actions: Hydroxyzine is used as a preoperative and postoperative adjunct for its sedative, antihistaminic, and anticholinergic activity.

Pharmacokinetics
Absorption: Absorbed rapidly and completely after oral administration. Serum levels peak in 2 to 4 hours. Sedation and other clinical effects are usually noticed in 15 to 30 minutes.
Distribution: Not well understood.
Metabolism: Metabolized almost completely in the liver.
Excretion: Metabolites are excreted primarily in urine; small amounts of drug and metabolites are found in feces. Half-life of drug is 3 hours. Sedative effects can last for 4 to 6 hours, and antihistaminic effects can persist for up to 4 days.

Contraindications and precautions
Contraindicated in patients hypersensitive to drug and during early pregnancy.
  Use cautiously with adjustments in dosage in elderly or debilitated patients.

Interactions
Drug-drug. Anticholinergics: Causes additive anticholinergic effects. Monitor patient closely.
Barbiturates, opioids, tranquilizers, other CNS depressants: Increases CNS effects. Reduce dose of CNS depressants by 50%.
Epinephrine: Blocks vasopressor action. If a vasoconstrictor is needed, use norepinephrine or phenylephrine.
Drug-lifestyle. Alcohol use: Causes additive effects. Discourage alcohol use.

Adverse reactions
CNS: drowsiness, involuntary motor activity.
GI: dry mouth.
Other: marked discomfort at I.M. injection site, hypersensitivity reactions.

Effects on lab test results
None reported.

Overdose and treatment
Signs and symptoms of overdose include excessive sedation and hypotension; seizures may occur.
 Treatment is supportive only. For recent oral ingestion, empty gastric contents through emesis or lavage. Correct hypotension with fluids and vasopressors (phenylephrine or metaraminol). Don’t give epinephrine because hydroxyzine may counteract its effect.

Special considerations
• Carefully review patient’s drug sensitivities and the use of CNS depressants for potential dosage adjustments.
• Drug therapy falsely elevates urinary 17-hydroxycorticosteroid levels. It also may cause false-negative skin allergen tests by attenuating or inhibiting the cutaneous response to histamine.
• Observe patient for excessive sedation, especially if he’s receiving other CNS depressants.
Pregnant patients
• Don’t use drug during early pregnancy because of potential risk to the fetus. Safety and efficacy in pregnant women haven’t been determined.
Breast-feeding patients
• It isn’t known whether drug appears in breast milk. Safety hasn’t been established in breast-feeding women.
Geriatric patients
• These patients may experience greater CNS depression and anticholinergic effects. Lower doses are indicated.

Patient education
• Advise patient to avoid tasks that require mental alertness or physical coordination until CNS effects of drug are known.
• Advise patient against use of other CNS depressants with hydroxyzine unless prescribed. Advise him to avoid alcohol and alcohol-containing products.
• Instruct patient to seek medical approval before taking OTC cold or allergy preparations that contain antihistamine, which may potentiate the effects of hydroxyzine.

Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE THREATENING.
◆ Canada only
◇ Unlabeled clinical use