Dimetindene, also sold under the brand name Fenistil, is an antihistamine/anticholinergic. It is a first generation selective H1 antagonist. Dimetindene is an atypical first generation H1 antagonist as it only minimally passes across the blood–brain barrier, and has no sedating effect after a single dose.
(S)-(+)-dimetindene is also a strong M2 receptor antagonist, with this enantiomer being more potent (up to 41-fold) for all muscarinic receptors assayed.
The (R)-(-)-enantiomer is the eutomer regarding the H1 receptor ((R)-isomer pA2 = 9.42; (S)-isomer pA2 = 7.48).
It was patented in 1958 and came into medical use in 1960.
Medical use Dimetindene is used orally and topically as an antipruritic. It is used topically to treat skin irritations, such as insect bites. Dimetindene is also administered orally to treat allergies, such as hay fever.
It is commonly formulated as its maleic acid salt, dimethindene maleate.
Names It is sold under the brand name Fenistil among others.
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