Acrivastine

Generic Name

Acrivastine

Brand Names

Benadryl Allergy Relief (UK formulation, contains acrivastine 8 mg and pseudoephedrine 60 mg in some versions)

Semprex-D (contains acrivastine and pseudoephedrine in US, but withdrawn from several markets)

Various generics depending on region

Drug Class

Second-generation non-sedating antihistamine

Selective H1-receptor antagonist

Often formulated in combination with a decongestant such as pseudoephedrine

Mechanism of Action

Acrivastine is a selective histamine H1-receptor antagonist

It blocks the action of endogenous histamine released during allergic responses

By competitively inhibiting histamine at H1 receptors in the respiratory tract, skin, and vasculature, it alleviates symptoms like sneezing, itching, rhinorrhea, and urticaria

Unlike first-generation antihistamines, acrivastine crosses the blood-brain barrier to a lesser extent and has reduced sedative properties

Indications

Seasonal allergic rhinitis (hay fever)

Perennial allergic rhinitis

Urticaria (hives)

Itching due to allergy

Allergic conjunctivitis (adjunctive use)

Symptomatic relief of upper respiratory allergy when combined with a decongestant

Dosing and Administration

Adults and children ≥12 years

Usual dose: 8 mg orally up to three times a day (maximum 24 mg/day)

Interval: Every 8 hours as needed

Duration of treatment depends on the clinical course of the allergic condition

Renal impairment

Caution in moderate renal dysfunction

Avoid in severe renal impairment

Hepatic impairment

Use cautiously as metabolism may be altered

No standard dose adjustment but monitor patient response

Pediatrics

Not recommended in children under 12 years of age

Safety and efficacy in pediatric populations below this age have not been established

Elderly

Use with caution due to potential age-related decline in renal function

Monitor for increased sensitivity or adverse reactions

Pharmacokinetics

Oral bioavailability: rapid absorption

Peak plasma concentration: within 1.5 hours

Half-life: approximately 1.5 hours

Excreted primarily in the urine unchanged

Minimal hepatic metabolism

Contraindications

Known hypersensitivity to acrivastine, pseudoephedrine (if in combination), or other ingredients

Severe renal impairment

Concomitant use with monoamine oxidase inhibitors (MAOIs) or within 14 days of stopping MAOIs

Severe hypertension or coronary artery disease (especially if pseudoephedrine is included)

Pregnancy and breastfeeding unless benefit outweighs risk

Precautions

Avoid use in patients with urinary retention, prostatic hypertrophy, or glaucoma (especially if product includes pseudoephedrine)

Caution in patients with mild to moderate renal impairment

In patients with hepatic impairment, monitor for signs of toxicity due to reduced clearance

Use with caution in combination with other CNS depressants or sedating agents despite low sedative profile

Not intended for long-term use unless under medical supervision

Patients should avoid alcohol and tasks requiring full alertness if CNS effects occur

Adverse Effects

Common

Headache

Dry mouth

Fatigue

Nausea

Drowsiness (less common than with first-generation antihistamines)

Less Common

Insomnia

Nervousness (especially in combinations with pseudoephedrine)

Palpitations

Tachycardia

Blurred vision

Rare but Serious

Hypersensitivity reactions (rash, angioedema)

Hypertension or cardiac arrhythmia (pseudoephedrine-containing forms)

Seizures (in overdose or susceptible patients)

Urinary retention

Pregnancy and Lactation

Pregnancy

Not recommended during pregnancy

Animal studies are insufficient, and human data are limited

Use only if benefit clearly outweighs risk

Lactation

May be excreted in breast milk

Risk of drowsiness or irritability in the infant

Avoid or use with caution in breastfeeding women

Use in Special Populations

Pediatrics

Not approved under 12 years of age

Elderly

Greater sensitivity to adverse effects possible

Increased risk of anticholinergic side effects and CNS disturbance

Renal Impairment

Dose adjustment or avoidance recommended due to renal clearance

Hepatic Impairment

Monitor carefully

Drug Interactions

CNS depressants (e.g., alcohol, benzodiazepines, opioids)

Additive CNS effects may occur

Monoamine oxidase inhibitors (MAOIs)

Contraindicated due to risk of hypertensive crisis (especially if pseudoephedrine included)

Other antihistamines

Avoid concurrent use due to risk of overdose and increased anticholinergic effects

Anticholinergic drugs

Risk of cumulative effects including dry mouth, blurred vision, urinary retention

CYP450 substrates or inhibitors

Minimal involvement; clinically significant interactions not commonly reported

Formulations

Oral capsules: 8 mg acrivastine

Combination formulations: acrivastine 8 mg + pseudoephedrine 60 mg

Available in blister packs or bottles depending on brand

Storage: store at room temperature away from moisture and heat

Patient Counseling Points

Take capsule with water and do not exceed three capsules in 24 hours

May be taken with or without food

Avoid alcohol and other sedating medications if drowsiness occurs

Do not drive or operate machinery if you feel sleepy or dizzy

Inform doctor if you are pregnant, planning pregnancy, or breastfeeding

Report any signs of allergic reaction, irregular heartbeat, or urinary problems

Do not use beyond recommended duration without medical supervision

Do not take multiple antihistamines simultaneously without medical advice

Monitor blood pressure if you have hypertension (especially if using a pseudoephedrine combination)