hydroxyzine (Rx)

Frequency Not Defined

Anticholinergic: Dry mouth

Central nervous system: Drowsiness (usually transitory and may disappear in a few days of continued therapy or upon reduction of the dose), involuntary motor activity (tremor, convulsions) usually with doses considerably higher than those recommended

Clinically significant respiratory depression has not been reported at recommended doses

Postmarketing Reports

Body as a whole: Allergic reaction

Nervous system: Headache

Psychiatric: Hallucination

Skin and appendages: Pruritus, rash, urticaria, fixed drug eruptions

Contraindications

Documented hypersensitivity or related product including cetirizine and levocetirizine and components of the formulation

Prolonged QT interval

SC, intra-arterial, or IV administration

Cautions

Nursing mothers

May cause CNS depression resulting in drowsiness; avoid driving or operating dangerous machinery

May cause oversedation and confusion in elderly patients; start on lower doses and monitor closely; avoid use

IM only for parenteral use; switch to PO ASAP

Use caution in patients with narrow-angle glaucoma, prostatic hyperplasia, or respiratory disease (asthma or COPD)

Hydroxyzine may rarely cause acute generalized exanthematous pustulosis (AGEP), a serious skin reaction characterized by fever and numerous small, superficial, non-follicular, sterile pustules, arising within large areas of edematous erythema; if signs or symptoms suggest AGEP, do not resume use of hydroxyzine and consider alternative therapy; avoid cetirizine or levocetirizine in patients who have experienced AGEP or other hypersensitivity reactions with hydroxyzine, due to risk of cross-sensitivity

Drug interaction interview

• Caution recommended during concomitant use of drugs known to prolong QT interval including Class 1A (e.g., quinidine, procainamide) or Class III (e.g., amiodarone, sotalol) antiarrhythmics, certain antipsychotics (e.g., ziprasidone, iloperidone, clozapine, quetiapine, chlorpromazine), certain antidepressants (e.g., citalopram, fluoxetine), certain antibiotics (e.g., azithromycin, erythromycin, clarithromycin, gatifloxacin, moxifloxacin); and others (e.g., pentamidine, methadone, ondansetron, droperidol)

Pregnancy category: Considered to be contraindicated in early (1st trimester) pregnancy until more human pregnancy data available; limited experience in human pregnancy, either for drug itself or drugs in same class or with similar mechanisms of action, including 1st trimester, current limited data suggests that the drug does not represent a significant risk of developmental toxicity including growth restriction, structural anomalies, functional/behavioral deficits, or death at any time in pregnancy

Lactation: Excretion in milk unknown; use with caution

Pregnancy Categories

A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

NA: Information not available.

Mechanism of Action

H1-receptor antagonist with low to moderate antihistaminic properties; inhibits respiratory, vascular, and GI smooth-muscle constriction

Moderate to high anticholinergic and antiemetic properties

Absorption

Onset: 15-30 min (PO)

Duration: Sedation, 4-6 hr; antipruritic, 1-12 hr; histamine-induced wheal and flare, 2-36 hr

Peak serum time: 1-2 hr

Distribution

Vd: 16 L/kg (adults); 23 L/kg (elderly)

Metabolism

Metabolized by liver

Elimination

Half-life: 20 hr (adults); 29 hr (elderly); 37 hr (hepatic dysfunction)

Excretion: Urine

IM Incompatibilities

Additive: Aminophylline, amobarbital, chloramphenicol, ketorolac, penicillin G sodium/potassium, pentobarbital, phenobarbital

Syringe: Aminophylline, dimenhydrinate, haloperidol, heparin, ketorolac, penicillin, pentobarbital, phenytoin, ranitidine, vitamin B complex with C

IM Compatibilities

Additive (partial list): Cisplatin, cyclophosphamide, cytarabine, dimenhydrinate, etoposide, lidocaine, methotrexate, nafcillin

Syringe (partial list): Atropine, buprenorphine, cimetidine, diphenhydramine, fentanyl, glycopyrrolate, lidocaine, meperidine, midazolam, morphine, promethazine, scopolamine, sufentanil