Classified as an antihistamine and anxiolytic and is also used as a tranquilizer.

Trade names Atarax, Vistaril


Administration orally and by intramuscular injection.

Bioavailability is high.

Protein binding at 93%.

Metabolism is hepatic.

Biological half-life in Adults: 20.0 hours, Children: 7.1 hours.

Excretion in Urine and feces.

A first-generation antihistamine.

It can be used for the treatment of itching, hyperalgesia, and motion sickness-induced nausea.

In some patients to relieve the effects of opioid withdrawal..

It has none of the abuse, dependence, addiction, and toxicity potential of other drugs used for the same range of therapeutic reasons.

Used to potentiate the analgesia of opioids and to alleviate some of their side effects, such as itching, nausea, and vomiting.

Has anxiolytic, antiobsessive, and antipsychotic activity.

Used primarily for the symptomatic relief of anxiety and tension associated with psychoneurosis

The second-generation antihistamine cetirizine is one of the metabolites of hydroxyzine produced in the human body.

Used in combination with opioids due to its ability to counteract the side effects of opioid pain medications, namely itchiness and nausea, and the fact that its sedative properties complement the pain-relieving effects of opioids.

Compared with other anxiolytic agents it is equivalent in efficacy, acceptability, and tolerability.

Can also be used for the treatment of allergic conditions, such as chronic urticaria, atopic or contact dermatoses, and histamine-mediated pruritus.

It is used as a form of non-barbiturate tranquilizer used in the pre-operative sedation and treatment of neurological disorders, such as psychoneurosis and other forms of anxiety or tension states.

For dentistry and obstetrics as well as other surgeries and procedures and acute pain situations like accidents, it is useful as a first-line anxiolytic and opioid adjunct because it lacks both antagonism and synergy with benzodiazepines and scopolamine.

Contraindications to its use include the administration of depressants and other compounds which affect the central nervous system.

Long-term use can lead to tardive dyskinesia.

Previous interactions with phenothiazine derivatives or pre-existing neuroleptic treatment may have had some contribution towards dyskinesia at the administration of hydroxyzine due to hypersensitivity caused due to the prolonged treatment.

Reactions include: deep sleep, incoordination, sedation, calmness, dizziness, hypotension, tinnitus, and headaches. dryness of the mouth and constipation.

Central nervous system problems such as hallucinations or confusion have been observed in rare cases, attributed mostly to overdosage.

It exhibits anxiolytic and sedative properties in many psychiatric patients.

Can act as an acute hypnotic, reducing sleep onset latency and increasing sleep duration

Has a definite risk of QT prolongation, and this side effect is more likely to occur in people with pre-existing cardiac disease, or with the use of other medicines known to prolong the QT interval.

Predominant mechanism of action is as a potent and selective histamine H1 receptor inverse agonist, which is responsible for its antihistamine and sedative effects.

Has very low affinity for the muscarinic acetylcholine receptors, and in accordance, has low or no propensity for producing anticholinergic side effects.

Shown to act more weakly as an antagonist of the serotonin 5-HT2A receptor, the dopamine D2 receptor, and the α1-adrenergic receptor.

Crosses the blood–brain barrier and exerts effects in the central nervous system.

Hydroxyzine can be administered orally or via intramuscular injection.

Orally is rapidly absorbed from the gastrointestinal tract, and it’s effect is notable in 30 minutes.

It is metabolized in the liver; the main metabolite (45%), cetirizine, is formed through oxidation of the alcohol moiety to a carboxylic acid by alcohol dehydrogenase, and overall effects are observed within one hour of administration.

Higher concentrations are found in the skin than in the plasma.

The main metabolite cetirizine, is less sedating, is non-dialyzable and possesses similar anti-histaminergic properties.

Should be administered carefully in the elderly with consideration given to possible reduced elimination.

The use of sedating drugs alongside it can cause oversedation and confusion.

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