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Mequitazine structure.svg
Clinical data
Trade namesPrimalan
AHFS/Drugs.comInternational Drug Names
ATC code
CAS Number
PubChem CID
CompTox Dashboard (EPA)
ECHA InfoCard100.045.005 Edit this at Wikidata
Chemical and physical data
Molar mass322.468 g/mol g·mol−1
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Mequitazine (trade name Primalan) is an H1 antagonist and anticholinergic of the phenothiazine chemical class. It is used to treat allergies and rhinitis.

It was patented in 1969 and came into medical use in 1976.[1]


Severe liver disease; premature infants or full-term neonates.

Special precautions[edit]

Pregnancy, lactation; severe cardiovascular disorders; asthma; angle-closure glaucoma, urinary retention, prostatic hyperplasia, pyloroduodenal obstruction; renal and hepatic impairment; elderly, children; epilepsy. May impair ability to drive or operate machinery.

Adverse reactions[edit]

CNS depression including slight drowsiness to deep sleep, lassitude, dizziness, incoordination. Headache, psychomotor impairment and antimuscarinic effects. Rarely, rashes and hypersensitivity reactions, blood disorders, convulsions, sweating, myalgia, paraesthesias, extrapyramidal effects, tremor, confusion, sleep and GI disturbances, tinnitus, hypotension, hair loss. Photosensitivity, jaundice.

Drug interactions[edit]

Enhances effects of CNS depressants e.g. alcohol, barbiturates, hypnotics, opioid analgesics, anxiolytics and antipsychotics. Can mask signs of ototoxicity caused by aminoglycosides. QT prolongation (which can lead to torsades de pointes arrhythmia) reported with spiramycin.

See also[edit]


  1. ^ Fischer, Jnos; Ganellin, C. Robin (2006). Analogue-based Drug Discovery. John Wiley & Sons. p. 548. ISBN 9783527607495.
  • Ramírez Chanona, N; del Rio Navarro, BE; Pérez Martín, J (November–December 2005). "Efficacy of Mequitazine (Primalan) on the Relief of Symptoms of Allergic Rhinoconjunctivitis in Children. Documented clinical experience". Revista Alergia Mexico (in Spanish). 52 (6): 221–5. PMID 16568706.
  • Theunissen, EL; Vermeeren, A; van Oers, AC; van Maris, I; Ramaekers, JG (February 2004). "A Dose-Ranging Study of the Effects of Mequitazine on Actual Driving, Memory and Psychomotor Performance as Compared to Dexchlorpheniramine, Cetirizine and Placebo". Clinical and Experimental Allergy. 34 (2): 250–8. doi:10.1111/j.1365-2222.2004.01874.x. PMID 14987305.
  • Nakamura, K; Yokoi, T; Kodama, T; Inoue, K; Nagashima, K; Shimada, N; Shimizu, T; Kamataki, T (February 1998). "Oxidation of Histamine H1 Antagonist Mequitazine is Catalyzed by Cytochrome P450 2D6 in Human Liver Microsomes" (PDF). The Journal of Pharmacology and Experimental Therapeutics. 284 (2): 437–42. PMID 9454781.
  • Persi, L; Dupin, O; Arnaud, B; Trinquand, C; Michel, FB; Bousquet, J (April 1997). "Efficacy of Mequitazine in Comparison with Placebo Assessed by Ocular Challenge with Allergen in Allergic Conjunctivitis". Allergy. 52 (4): 451–4. doi:10.1111/j.1398-9995.1997.tb01028.x. PMID 9188930.