ヒドロキシジン

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 norepinephrine or metaraminol. Do not use epinephrine as hydroxyzine hydrochloride counteracts its pressor action. 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. (L1712)

Hydroxyzine has been shown to inhibit and reverse the vasopressor effect of epinephrine. If a vasopressor agent is required in patients receiving hydroxyzine, norepinephrine or metaraminol should be used; epinephrine should not be used.

Additive anticholinergic effects may occur when hydroxyzine is administered concomitantly with other anticholinergic agents.

Hydroxyzine may be additive with, or may potentiate the action of, other CNS depressants such as opiates or other analgesics, barbiturates or other sedatives, anesthetics, or alcohol. When hydroxyzine is used concomitantly with other CNS depressants, caution should be used to avoid excessive sedation, and the manufacturers recommend that dosage of the CNS depressant be reduced by up to 50%.

Mechanism of a rise of blood hydroxyzine concentrations due to ethanol administration was investigated used rabbits. When 10 mg/kg hydroxyzine dihydrochloride were orally administered together with 10 mL/kg of 1 to 15% ethanol solution, blood hydroxyzine concentrations rised in all rabbits given ethanol solution more than 10%. When 10 mL/kg of 15% ethanol solution were orally administered at 1, 2 or 3 hours before oral administration of hydroxyzine, blood hydroxyzine concentrations rised markedly in all cases. Blood hydroxyzine concentrations rised little or a little when hydroxyzine were orally administered immediately after intravenous administration of 5 mL/kg of 20% ethanol solution. It was considered that the main mechanism of a rise of blood hydroxyzine concentration was not metabolic interaction between hydroxyzine and ethanol, but an enhancement of intestinal absorption of hydroxyzine due to ethanol. It was also found that hydroxyzine in blood distributed rapidly into bodily tissues.

Despite widespread use, hydroxyzine has not been linked to liver test abnormalities or to clinically apparent liver injury. Indeed, hydroxyzine is commonly used for the pruritus associated with liver disease. The reason for its safety may relate to low daily dose and limited duration of use.

Hydroxyzine competes with histamine for binding at H₁-receptor sites on the effector cell surface, resulting in suppression of histaminic edema, flare, and pruritus. The sedative properties of hydroxyzine occur at the subcortical level of the CNS. Secondary to its central anticholinergic actions, hydroxyzine may be effective as an antiemetic.

/SIGNS AND SYMPTOMS/ In general, overdosage of hydroxyzine may be expected to produce effects that are extensions of common adverse reactions; excessive sedation has been the principal effect reported. Hypotension, although rare, may also occur.

/CASE REPORTS/ A /case of/ neonatal withdrawal syndrome associated with maternal hydroxyzine treatment (150 mg/day) confirmed by measurements of hydroxyzine plasma concentrations in the mother and infant after birth /is reported/. Hydroxyzine plasma concentrations were measured by liquid chromatography-mass spectrometry. Neurological symptoms with low neonatal concentrations of hydroxyzine may be due to a withdrawal syndrome. According to previous observations and this case report, clinicians should be warned of this possible rare neurological complication of hydroxyzine in neonates born from long term treated mothers.

/CASE REPORTS/ A case of hydroxyzine toxicity following accidental ingestion in a 13-month old female infant has been presented. A plasma hydroxyzine concentration 8.5 hours after the acute ingestion was 102.7 ug/mL and toxicity was manifested primarily by generalized seizures and sinus tachycardia. General supportive care and seizure control with physostigmine resulted in complete recovery within 72 hours.

/CASE REPORTS/ ... A case report of neonatal withdrawal of a female infant with Apgar scores of 7 and 9 weighing 2950 g delivered of a mother who had been treated during her entire pregnancy with hydroxyzine 600 mg daily and phenobarbital 60 mg daily. The infant's jitteriness; tachypnea; poor suck and feeding; irritability; clonic movement; and shrill cry are all suggestive of a narcotic withdrawal syndrome. Since the small amount of phenobarbital taken in the weeks preceding delivery would not be expected to result in an early neonatal withdrawal syndrome, it is believed that the patient's symptoms were a result of withdrawal from hydroxyzine.

For more Human Toxicity Excerpts (Complete) data for HYDROXYZINE (8 total), please visit the HSDB record page.

Benchmark Dataset for the Liver Toxicity Knowledge Base (LTKB)

hydroxyzine

Vistaril®

Anxiolytics

Not Applicable

no-DILI-concern

/VETERINARY CASE REPORTS/ Terrier which had eaten 450 mg of this compd became highly excited and aggressive with rapid pulse and respiration and twitching of voluntary muscles.

//VETERINARY CASE REPORTS/ Monkeys: ... produces no marked behavioral changes, but may cause sedation and ataxia, occasionally preceded by convulsions.

/VETERINARY CASE REPORTS/ Hydroxyzine is a commonly prescribed H1-receptor antagonist in small animal practice. The most common adverse effect reported after therapeutic dosing is mild sedation; severe reactions resulting in coma have occasionally been reported in children. ... a case of large po hydroxyzine exposure causing in coma and apnea in a dog /is presented/. Exposure was confirmed with gas chromatography/mass spectrometry analysis of urine. Extensive therapeutic measures to enhance drug elimination and assist ventilation were required for 11 d. The positive outcome justifies critical care of similarly exposed animals. Veterinarians should be aware of the potential for coma and apnea secondary to hydroxyzine exposure.

Emergency and supportive measures: Maintain an open airway and assist ventilation if necessary. Treat coma, seizures, hyperthermia, and atypical ventricular tachycardia if they occur. Monitor the patient for at least 6-8 hours after ingestion. /Antihistamines/

Specific drugs and antidotes: There is no specific antidote for antihistamine overdose. ... /Antihistamines/

Decontamination: Administer activated charcoal orally if conditions are appropriate. Gastric lavage is not necessary after small to moderate ingestions if activated charcoal can be given promptly. Because of slowed gastrointestinal motility, gut decontamination procedures may be helpful even in late-presenting patients. /Antihistamines/

Most patients require only symptomatic and supportive care. Treatment is focused on controlling agitation, maintaining airway, reversing hyperthermia, and supporting hemodynamic function. Gastrointestinal decontamination is not essential, but if not more than 1 hour has elapsed since ingestion of the drug, activated charcoal may be considered. In view of the potential cardiac toxicity in addition to maintenance of the airway, breathing, and circulatory status of the patient, observation for dysrhythmia is warranted. Clinical assessment for signs that may indicate impending seizure activity (hypertonicity, hyperreflexia, or myoclonic jerking) is important. Patients with altered mental status, seizure, abnormal vital signs, or dysrhythmia are typically admitted. /Antihistamines/

For more Antidote and Emergency Treatment (Complete) data for HYDROXYZINE (7 total), please visit the HSDB record page.

The Approved Drug Products with Therapeutic Equivalence Evaluations List identifies currently marketed prescription drug products, incl hydroxyzine hydrochloride, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act. /Hydroxyzine hydrochloride/

The Approved Drug Products with Therapeutic Equivalence Evaluations List identifies currently marketed prescription drug products, incl hydroxyzine pamoate, approved on the basis of safety and effectiveness by FDA under sections 505 of the Federal Food, Drug, and Cosmetic Act. /Hydroxyzine pamoate/

Treatment of chronic urticaria, dermatitis, and histamine-mediated pruritus ... also effective as an antiemetic, for relief of anxiety and tension, and as a sedative.

Hydroxyzine is an antihistaminic diarylalkylpiperazine which is used as an anxiolytic. It has no cortical depressant activity; its anxiolytic action could be explained by its suppressive effect on neuronal activity in subcortical areas. A myorelaxant activity has also been demonstrated experimentally.

Hydroxyzine is a sedative piperazine antihistamine with anxiolytic, antiemetic, antisecretory, and bronchodilator effects. Hydroxyzine hydrochloride is administered orally ... for preanesthetic sedation. While this drug potentiates other CNS depressants and lowers the required amount of the general anesthetic, it does not prolong anesthesia.

Hydroxyzine has antihistaminic, antimuscarinic, and central nervous properties. Hydroxizine is used ... in the treatment of allergic diseases ...

For more Uses (Complete) data for HYDROXYZINE (10 total), please visit the HSDB record page.

Use (kg; approx.) in Germany (2009): >250

(RS)-1-[(4-clorophenyl)phenylmethyl]piperazine

decloxizine

Morren, US Patent 2899436 (1959 To UCB)

By condensing p-chlorobenzhydryl chloride with n-[2-(2-hydroxyethoxy)ethyl]piperazine. Conversion to hydrochloride may be effected by dissolving base in double molar quantity of hydrochloric acid and evaporating soln to dryness. /Hydroxyzine hydrochloride/

Table: Hydroxyzine Hydrochloride Preparations [Table#4435]

Table: Hydroxyzine Pamoate Preparations [Table#4436]