Hydroxyzine

INDICATIONS For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested. Useful in the management of pruritus due to allergic conditions such as chronic urticaria and atopic and contact dermatoses, and in histamine-mediated pruritus. As a sedative when used as premedication and following general anesthesia, hydroxyzine may potentiate meperidine (Demerol ® ) and barbiturates, so their use in pre-anesthetic adjunctive therapy should be modified on an individual basis. Atropine and other belladonna alkaloids are not affected by the drug. Hydroxyzine is not known to interfere with the action of digitalis in any way and it may be used concurrently with this agent. The effectiveness of hydroxyzine as an antianxiety agent for long-term use, that is, more than 4 months, has not been assessed by systematic clinical studies. The physician should reassess periodically the usefulness of the drug for the individual patient.

CLINICAL PHARMACOLOGY Hydroxyzine pamoate is unrelated chemically to the phenothiazines, reserpine, meprobamate, or the benzodiazepines. Hydroxyzine pamoate is not a cortical depressant, but its action may be due to a suppression of activity in certain key regions of the subcortical area of the central nervous system. Primary skeletal muscle relaxation has been demonstrated experimentally. Bronchodilator activity, and antihistaminic and analgesic effects have been demonstrated experimentally and confirmed clinically. An antiemetic effect, both by the apomorphine test and the veriloid test, has been demonstrated. Pharmacological and clinical studies indicate that hydroxyzine in therapeutic dosage does not increase gastric secretion or acidity and in most cases has mild antisecretory activity. Hydroxyzine is rapidly absorbed from the gastrointestinal tract and hydroxyzine pamoate clinical effects are usually noted within 15 to 30 minutes after oral administration.

DOSAGE For symptomatic relief of anxiety and tension associated with psychoneurosis and as an adjunct in organic disease states in which anxiety is manifested: in adults, 50 mg to 100 mg q.i.d.; children under 6 years, 50 mg daily in divided doses; and over 6 years, 50 mg to 100 mg daily in divided doses. For use in the management of pruritus due to allergic conditions such as chronic urticaria and atopic and contact dermatoses, and in histamine-mediated pruritus: in adults, 25 mg t.i.d. or q.i.d.; children under 6 years, 50 mg daily in divided doses; and over 6 years, 50 mg to 100 mg daily in divided doses. As a sedative when used as a premedication and following general anesthesia: 50 mg to 100 mg in adults, and 0.6 mg/kg in children. When treatment is initiated by the intramuscular route of administration, subsequent doses may be administered orally. As with all medications, the dosage should be adjusted according to the patient’s response to therapy.

ADVERSE REACTIONS Side effects reported with the administration of hydroxyzine pamoate are usually mild and transitory in nature. Skin and Appendages Oral hydroxyzine hydrochloride is associated with Acute Generalized Exanthematous Pustulosis (AGEP) and fixed drug eruptions in post-marketing reports. Anticholinergic Dry mouth. Central Nervous System Drowsiness is usually transitory and may disappear in a few days of continued therapy or upon reduction of the dose. Involuntary motor activity, including rare instances of tremor and convulsions, has been reported, usually with doses considerably higher than those recommended. Clinically significant respiratory depression has not been reported at recommended doses. Cardiac System QT prolongation, Torsade de Pointes. In post-marketing experience, the following additional undesirable effects have been reported: Body as a Whole Allergic reaction Nervous System Headache Psychiatric Hallucination Skin and Appendages Pruritus, rash, urticaria

WARNINGS Nursing Mothers It is not known whether this drug is excreted in human milk. Since many drugs are so excreted, hydroxyzine should not be given to nursing mothers.

CONTRAINDICATIONS Hydroxyzine, when administered to the pregnant mouse, rat, and rabbit, induced fetal abnormalities in the rat and mouse at doses substantially above the human therapeutic range. Clinical data in human beings are inadequate to establish safety in early pregnancy. Until such data are available, hydroxyzine is contraindicated in early pregnancy. Hydroxyzine is contraindicated in patients with a prolonged QT interval. Hydroxyzine pamoate is contraindicated for patients who have shown a previous hypersensitivity to any component of this medication. Hydroxyzine is contraindicated in patients with known hypersensitivity to hydroxyzine products, and in patients with known hypersensitivity to cetirizine hydrochloride or levocetirizine hydrochloride.

OVERDOSAGE The most common manifestation of overdosage of hydroxyzine pamoate is hypersedation. Other reported signs and symptoms were convulsions, stupor, nausea and vomiting. As in the management of overdosage with any drug, it should be borne in mind that multiple agents may have been taken. If vomiting has not occurred spontaneously, it should be induced. Immediate gastric lavage is also recommended. General supportive care, including frequent monitoring of the vital signs and close observation of the patient, is indicated. Hypotension, though unlikely, may be controlled with intravenous fluids and vasopressors ( do not use epinephrine as hydroxyzine counteracts its pressor action ). Caffeine and Sodium Benzoate Injection, USP, may be used to counteract central nervous system depressant effects. Hydroxyzine overdose may cause QT prolongation and Torsade de Pointes. ECG monitoring is recommended in cases of hydroxyzine overdose. There is no specific antidote. It is doubtful that hemodialysis would be of any value in the treatment of overdosage with hydroxyzine. However, if other agents such as barbiturates have been ingested concomitantly, hemodialysis may be indicated. There is no practical method to quantitate hydroxyzine in body fluids or tissue after its ingestion or administration.