Antihistamines hydroxyzine

Yet another nonsedating zwitterionic H-1 antihistamine consists of the product from metabolism of the terminal hydroxyl of the potent antihistamine hydroxyzine terminating in hydroxymethyl instead of a carboxylic acid. This compound, cetirzine (123), can be obtained in straightforward fashion by alkylation of the monosubstituted piperazine 120 with halide 121, via the amide 122 [27]. 

Antihistamines. Some clinicians have prescribed the antihistamine, hydroxyzine (Vistaril, Atarax) to treat anxiety. A typical regimen is 25 mg administered one to three times per day as needed for anxiety. The use of hydroxyzine to treat anxiety is largely driven by concern regarding the addictive potential of benzodiazepines. In reality, hydroxyzine does little to relieve anxiety other than produce drowsiness. Because other nonaddictive anxiolytics are available, we do not recommend routine use of this largely ineffective treatment. 

Itching may respond to treatment with antihistamines (hydroxyzine or diphenhydramine) emollient skin creams or occlusive agents are effective for dry, peeling skin avoid corticosteroids may counteract the antitumor effects ofIL-2. 

The antihistamine hydroxyzine is an effective antianxiety agent, but only at doses (-400 mg/day) that produce marked sedation (see Chapter 24). Propranolol and metoprolol, lipophilic fi adrenergic receptor antagonists that enter the CNS, can reduce the autonomic symptoms (nervousness and muscle tremor) associated with specific situational or social phobias but do not appear to be effective in generalized anxiety or panic disorder (see Chapter 10). Similarly, other antiadrener-gic agents, including clonidine, may modify autonomic expression of anxiety but are not demonstrably usfful in the treatment of severe anxiety disorders. 

Cetirizine, the acid metabolite from oxidation of the primary alcohol of the antihistamine hydroxyzine (Fig. 37.15 and Table 37.6), is a widely used antihistamine (38). It has a long duration of action and is highly selective for Hi receptors. No cardiotoxicity has been reported, but some drowsiness occurs. The R-enantiomer of cetirizine, levocetirizine, is marketed in Europe. Levocetirizine has higher affinity than its S-enantiomer for the Hi receptor (>30-fold) and is more slowly dissociated by more than 20-fold from the receptor (39). Thus, the antihistaminic... 

Cardiovascular Like some other antihistamines, hydroxyzine can cause prolongation of the QT interval [18" ]. 

Pharmacologic Therapy Topical emollients have been used as treatment for pruritus in patients with dry skin, but are often not effective in relieving pruritus associated with CKD. Antihistamines, such as hydroxyzine 25 to 50 mg or diphenhydramine 25 to 50 mg orally or intravenously, are used as... 

Antihistamines are frequently used, but few clinical studies support their efficacy. A sedating antihistamine (e.g., hydroxyzine, diphenhydramine) can offer an advantage by facilitating sleep because pruritus is often worse at night. 

Intranasal corticosteroids are the most effective treatment for allergic rhinitis during pregnancy. Beclomethasone and budesonide have been used most. Nasal cromolyn and first-generation antihistamines (chlorpheniramine, tripelennamine, and hydroxyzine) are also considered first-line therapy. Loratadine and cetirizine have not been as extensively studied. 

Antihistamines. After alcohol, antihistamines are the most commonly self-administered sleep medications. Foremost among these is diphenhydramine (Benadryl), which is also available as a component in a variety of over-the-counter nighttime medications including Tylenol PM and Excedrin PM. Prescription antihistamines like hydroxyzine (Vistaril, Atarax) are also occasionally used to treat insomnia. Finally, it is the antihistamine effect of some antidepressants and anti-psychotics that contribute to their utility as sedative-hypnotics. 

Antihistamines help to initiate sleep and, depending on their half-life, may produce little hangover. They are not addictive and therefore may be preferred for patients with a history of substance abuse. Diphenhydramine is usually an effective hypnotic at 25-50 mg at bedtime. The same dose tends to be effective for hydroxyzine. 

First-generation antihistamines Flypersensitivity to specific or structurally related antihistamines newborns or premature infants nursing mothers monoamine oxidase (MAO) therapy pregnancy (hydroxyzine) angle-closure glaucoma, stenosing peptic ulcer, symptomatic prostatic hypertrophy, bladder neck obstruction, pyloroduodenal obstruction, elderly, debilitated patients (cyproheptadine). 

Bronchodilator activity, antihistaminic, and analgesic effects have been confirmed. Hydroxyzine has antispasmodic properties, and an antiemetic effect has been demonstrated. 

Several Hi histamine antagonists (e.g., diphenhydramine, promethazine, and hydroxyzine) have been used as sedative-hypnotics, since they produce some degree of sedation. While this sedation is usually considered a side effect of their antihistaminic activity, in some cases the sedation is sufficient to allow the drugs to be used in the treatment of anxiety and sleep disturbances. For these drugs, the anxiolytic properties are thought to be a direct consequence of their ability to produce sedation. 

Hydroxyzine hydrochloride Atarax, Vistarit) is the antihistamine with the greatest use in the treatment of anxiety. It is often used to reduce the anxiety that is associated with anesthesia and surgery. It also produces sedation, dries mucous membranes (via an anticholinergic mechanism), and has antiemetic activity. A more extensive discussion of the pharmacology of the Hj-receptor antagonists is found in Chapter 38. 

Anticholinergics and antihistamines chlorpheniramine (Chlor-Trimeton), diphenhydramine (Benadryl), hydroxyzine (Vistaril and Atarax), cyproheptadine (Periactin), promethazine (Phenergan), dexchlorpheniramine (Polaramine) All nonprescription and many prescription antihistamines may have potent anticholinergic properties. Nonanticholinergic antihistamines are preferred in elderly patients when treating allergic reactions. High... 

The first generation Hi blockers (including diphenhydramine and hydroxyzine) cross the blood-brain barrier. Subsequent generations of antihistamines have been developed so that they do not cross the blood-brain barrier, and therefore are not effective as sedatives or anxiolytics. 

The first-generation antihistamines include diphenhydramine and hydroxyzine. They are both well absorbed from the GI tract, and peak plasma concentrations occur within 2 to 3 hours. 

Antihistamines have been used for several decades in the treatment of anxiety in children (Tader, 1988). Prescription data show that antihistamines are widely used in pediatric psychiatric practices (Zito et ah, 2000). Diphenhydramine and hydroxyzine have been reported to modify anxiety symptoms in children with various psychiatric disorders. They are mainly used as a sedative in patients with insomnia. Occasionally they are used for mild acute agitation (AACAP, 1997). 

For those with a history of substance abuse or intolerance to benzodiazepines and the elderly, caution must be used in controlling anxiety. In these cases, benzodiazepines may exacerbate other conditions. Preliminary reports suggest that antipsychotics such as quetiapine may alleviate symptoms of anxiety. Other strategies include use of antihistamines such as hydroxyzine and diphenhydramine. 

Antihistamines dimenhydrinate hydroxyzine hydrochloride promethazine hydrochloride... 

Droperidol and hydroxyzine (25-50 mg IM) is sometime used for their antiemetic activity. Hydroxyzine has antianxiety, antihistaminic and anticholinergic properties also. 

A number of other medications may be used pre-operatively to achieve various goals (see Table 11-2).5,40 Antihistamines (promethazine, hydroxyzine)... 

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