Mequitazine

{{Short description|Chemical compound}}

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| IUPAC_name = 10-(1-Azabicyclo[2.2.2]octan-3-ylmethyl)phenothiazine

| image = Mequitazine structure.svg

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| tradename = Primalan

| Drugs.com = {{drugs.com|international|mequitazine}}

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| ATC_prefix = R06

| ATC_suffix = AD07

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| legal_EU = Rx-only

| legal_EU_comment = {{cite web | title = Active substance: mequitazine | url = https://www.ema.europa.eu/documents/psusa/mequitazine-list-nationally-authorised-medicinal-products-psusa/00001986/202001_en.pdf | work = List of nationally authorised medicinal products | location = Amsterdam | publisher = European Medicines Agency | date = 15 October 2020 }}

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| CAS_number_Ref = {{cascite|correct|??}}

| CAS_number = 29216-28-2

| PubChem = 4066

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| DrugBank = DB01071

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| ChemSpiderID = 3926

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| UNII = Y463242LY2

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| KEGG = D01324

| C=20 | H=22 | N=2 | S=1

| smiles = c1ccc2c(c1)Sc1ccccc1N2CC1CN2CCC1CC2

| StdInChI = 1S/C20H22N2S/c1-3-7-19-17(5-1)22(18-6-2-4-8-20(18)23-19)14-16-13-21-11-9-15(16)10-12-21/h1-8,15-16H,9-14H2

| StdInChIKey = HOKDBMAJZXIPGC-UHFFFAOYSA-N

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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.{{cite book | vauthors = Fischer J, Ganellin CR |title=Analogue-based Drug Discovery |date=2006 |publisher=John Wiley & Sons |isbn=9783527607495 |page=548 |url=https://books.google.com/books?id=FjKfqkaKkAAC&pg=PA548 |language=en}}

Contraindications

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

Special precautions

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

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

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.

Synthesis

Same precursor as for Quifenadine. Note that the synthesis has changed over the years from the original. One route seems to involve a Johnson–Corey–Chaykovsky reaction of the starting ketone, although another secondary route is also discussed.

File:Mequitazine synthesis.svg

References

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Further reading

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  • {{cite journal | vauthors = Ramírez Chanona N, del Rio Navarro BE, Pérez Martín J | title = [Efficacy of mequitazine (Primalan) on the relief of symptoms of allergic rhinoconjunctivitis in children. Documented clinical experience] | language = Spanish | journal = Revista Alergia Mexico | volume = 52 | issue = 6 | pages = 221–225 | date = November–December 2005 | pmid = 16568706 }}
  • {{cite journal | vauthors = Theunissen EL, Vermeeren A, van Oers AC, van Maris I, Ramaekers JG | title = A dose-ranging study of the effects of mequitazine on actual driving, memory and psychomotor performance as compared to dexchlorpheniramine, cetirizine and placebo | journal = Clinical and Experimental Allergy | volume = 34 | issue = 2 | pages = 250–258 | date = February 2004 | pmid = 14987305 | doi = 10.1111/j.1365-2222.2004.01874.x | s2cid = 23019669 }}
  • {{cite journal | vauthors = Nakamura K, Yokoi T, Kodama T, Inoue K, Nagashima K, Shimada N, Shimizu T, Kamataki T | display-authors = 6 | title = Oxidation of histamine H1 antagonist mequitazine is catalyzed by cytochrome P450 2D6 in human liver microsomes | journal = The Journal of Pharmacology and Experimental Therapeutics | volume = 284 | issue = 2 | pages = 437–442 | date = February 1998 | pmid = 9454781 | url = http://jpet.aspetjournals.org/content/jpet/284/2/437.full.pdf }}
  • {{cite journal | vauthors = Persi L, Dupin O, Arnaud B, Trinquand C, Michel FB, Bousquet J | title = Efficacy of mequitazine in comparison with placebo assessed by ocular challenge with allergen in allergic conjunctivitis | journal = Allergy | volume = 52 | issue = 4 | pages = 451–454 | date = April 1997 | pmid = 9188930 | doi = 10.1111/j.1398-9995.1997.tb01028.x | s2cid = 34785561 }}

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