Mequitazine

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.

References

References

1. (15 October 2020). "Active substance: mequitazine". European Medicines Agency.
2. (2006). "Analogue-based Drug Discovery". John Wiley & Sons.
3. {{cite patent
4. (November 2009). "Expedient synthesis of mequitazine an antihistaminic drug by palladium catalyzed allylic alkylation of sodium phenothiazinate". Chemical & Pharmaceutical Bulletin.
5. (June 1999). "An efficient synthesis of mequitazine.". Organic Preparations and Procedures International.
6. (July 2011). "Asymmetric synthesis of (+)-mequitazine from quinine". Organic Letters.