brands

Class

• Neuroscience-based Nomenclature: histamine receptor antagonist (H-RAn)
• Antihistamine (anxiolytic, hypnotic, antiemetic)

Hydil commonly prescribed for

(Bold for FDA approved)

How Hydil works

• Blocks histamine 1 receptors

How long until Hydil works

• 15–20 minutes (oral administration)

• Some immediate relief with first dosing is common; can take several weeks with daily dosing for maximal therapeutic benefit in chronic conditions

Notable Side Effects

• Sedation

• Dry mouth, tremor

Life Threatening Side Effects

• Rare tremor and convulsions (generally at high doses)

• QTc prolongation, torsades de pointes

• Acute generalized exanthematous pustulosis

• Rare cardiac arrest, death (intramuscular formulation combined with CNS depressants)

• Bronchodilation

• Respiratory depression

weight gain

unusual

sedation

common

What to do about Hydil side effects

• Wait

• Wait

• Wait

• Switch to another agent

usual dosage range

• Anxiety: 50–100 mg 4 times a day

• Sedative: 50–100 mg oral, 25–100 mg intramuscular injection

• Pruritus: 75 mg/day divided into 3–4 doses

Dosage Forms

• Tablet 10 mg, 25 mg, 50 mg

• Capsule 25 mg, 50 mg, 100 mg

• Oral liquid 10 mg/5 mL

• Intramuscular 25 mg/mL, 50 mg/mL

long term use

• Evidence of efficacy for up to 16 weeks

• Tolerance to sedation usually develops

habit forming

• No

Renal Impairment

• Dosage adjustment may not be necessary

Hepatic Impairment

• Dosage adjustment may not be necessary

Cardiac Impairment

• Contraindicated in patients with a QTc prolongation

Elderly

• Some patients may tolerate lower doses better

• Elderly patients may be more sensitive to sedative and anticholinergic effects

• Should be avoided in elderly patients with dementia

Children and Adolescents

• Anxiety, pruritus (6 and older): 50–100 mg/ day in divided doses

• Anxiety, pruritus (under 6): 50 mg/day in divided doses

• Sedative: 0.6 mg/kg

• Small children should not receive hydroxyzine by intramuscular injection in the periphery of the upper quadrant of the buttock unless absolutely necessary because of risk of damage to the sciatic nerve

• Hyperactive children should be monitored for paradoxical effects

Pregnancy

• Hydroxyzine is contraindicated in early pregnancy

• Hydroxyzine intramuscular injection can be used prepartum, reducing narcotic requirements by up to 50%

Breast Feeding

• Unknown if hydroxyzine is secreted in human breast milk, but all psychotropics are assumed to be secreted in breast milk

• Recommended either to discontinue drug or formula feed