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Loratadine (Molecule of the Month for July 1999)


Long-Acting Antihistamine/Extended Release Decongestant

Loratadine is a long-acting tricyclic antihistamine with selective peripheral histamine H1-receptor antagonistic activity. Human histamine skin wheal studies following single and repeated oral doses of loratadine have shown that the drug exhibits an antihistaminic effect beginning within 1 to 3 hours, reaching a maximum at 8 to 12 hours and lasting in excess of 24 hours.There was no evidence of tolerance to this effect developing after 28 days of dosing with loratadine.

Pharmacokinetic studies following showed that loratadine is rapidly absorbed and extensively metabolized to an active metabolite (descarboethoxyloratadine)

Formal Chemical Name (IUPAC)

Picture of Loratadine

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Loratadine structure
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Picture of Loratadine

C22 H23 Cl N2 O2

Update by Karl Harrison
(Molecule of the Month for July 1999 )