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RESPIRATORY SYSTEM › ANTIHISTAMINES FOR SYSTEMIC USE › ANTIHISTAMINES FOR SYSTEMIC USE › Phenothiazine derivatives
mequitazine
R06AD07
Forms & Strengths
- Tablets 5 mg
- Tablets 10 mg
- Oral solution 2 mg/mL
Adult Dosing
- 5 mg 2‑3 times daily (max 20 mg/day)
- 10 mg twice daily (max 20 mg/day)
- Adjust in renal/hepatic impairment
Pediatric Dosing
- 0.25‑0.5 mg/kg per dose up to 5 mg, 2‑3 times daily (max 15 mg/day)
- Not recommended <6 years
Indications
- Allergic rhinitis
- Seasonal/perennial allergic conjunctivitis
- Urticaria and other histamine‑mediated skin reactions
Mechanism of Action
- Competitive antagonism of peripheral H1 histamine receptors
- Additional anticholinergic and anti‑serotonergic activity reducing nasal secretions
Contraindications
- Hypersensitivity to mequitazine or other piperazine antihistamines
- Narrow‑angle glaucoma
- Severe hepatic impairment
- Pregnancy (category C)
Adverse Reactions
- Sedation, somnolence
- Dry mouth, blurred vision, urinary retention
- Constipation, nausea
- Dizziness, headache
- Weight gain
- Extrapyramidal symptoms (rare)
- QT prolongation (rare)
Drug Interactions
- Additive CNS depression with alcohol, opioids, benzodiazepines
- Increased anticholinergic load with other anticholinergics
- CYP2D6 inhibitors may raise plasma levels
- Concurrent QT‑prolonging drugs increase arrhythmia risk
- MAO inhibitors may enhance antihistaminic effects
Curated Content: Needs Vetting Before Put to Clinical Use