hydroxyzine (Atarax, Vistaril)

Introduction

Tradenames:

• Atarax (hydroxyzine HCl), Vistaril (hydroxyzine pamoate).

Indications

• sedation
  • symptomatic relief of anxiety or tension
• pruritus caused by allergic conditions
  • urticaria
• insomnia
• agitation caused by alcohol withdrawal
• control of nausea/vomiting
• used in conjunction with opiates for additive analgesia
• prevention of motion sickness

Contraindications

Caution:

• narrow-angle glaucoma
• prostatic hypertrophy
• bladder neck obstruction
• avoid in early pregnancy

pregnancy category = c

safety in lactation = -

Dosage

• 0.5 mg/kg up to 25-100 mg PO/IM* every 4-6 hours PRN (pamoate).
• 10-20 mg every 4-6 hours (HCl {Atarax})

Tabs: 10, 25, 50, 100 mg (pamoate). 10 mg, 20 mg (HCl)

Suspension: 10 & 25 mg/5 mL.

Injection: 25 mg/mL (1 mL); 50 mg/mL (1 mL, 2 mL, 10 mL) *Do not give IV or SC; thrombosis & digital gangrene may occur.

Pharmacokinetics

• rapidly absorbed from GI tract after oral administration
• onset of sedative effect occurs within 15-30 minutes
• effects persist for 4-6 hours after a single oral dose
• metabolized by liver

elimination via liver

Adverse effects

• common (> 10%)
  • drowsiness (slight to moderate)
  • thickening of bronchial secretions
• less common (1-10%)
  • headache, fatigue, increased appetite, weight gain, nervousness, dizziness, nausea, diarrhea, abdominal pain, dry mouth, pharyngitis, arthralgia
• uncommon (< 1%)
  • angioedema, bronchospasm, depression, edema, epistaxis, hepatitis, myalgia, palpitations, paresthesia, photosensitivity, rash, hypotension, sedation, paradoxical excitement, insomnia, tremor, blurred vision, urinary retention
• other
  • ataxia

• drug adverse effects of H1 receptor antagonists
• drug adverse effects of psychotropic agents
• drug adverse effects of sedatives

Drug interactions

• additive effects with other CNS depressants
• MAO inhibitors increase anticholinergic effects
• hydroxyzine may block vasopressor effect of epinephrine
• additive effects with other anticholinergic agents

Mechanism of action

• piperazine antihistamine, H1 receptor antagonist
• anticholinergic agent
• antispasmodic agent
• local anesthetic
• antimotion properties

More general terms

• piperazine
• H1 receptor antagonist (antihistamine)
• sedative/hypnotic (tranquilizer)
• antipruritic agent

Component of

• hydroxyzine/labetalol
• ephedrine/hydroxyzine/theophylline

Database

• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=3658
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=25096
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=91513
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=22287
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=71612
• PubChem: http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=657362