indication

Indicated as symptomatic treatment of allergic reactions: urticaria, allergies of the upper respiratory tract such as hey fever and perennial rhinitis, food and drug allergies; pruritus of various origins, except pruritus due to cholestasis; insect bites. Dimethindene is also indicated for pruritus in eruptive skin diseases such as chicken-pox. Dimethindene can also be used as an adjuvant in eczema and other pruriginous dermatoses of allergic origin.

pharmacology

Dimethindene occurs as a racemic mixture. The (S)-(+)-dimethindene is a potent M2-selective muscarinic receptor antagonist (with lower affinity for M1, M3, and M4 muscarinic receptors). The (R)-(-)-enantiomer is the eutomer (responsible for bioactivity) for histamine H1 receptor binding.

mechanism of action

Dimethindene is a selective histamine H1 antagonist and binds to the histamine H1 receptor. This blocks the action of endogenous histamine, which subsequently leads to temporary relief of the negative symptoms brought on by histamine.

toxicity

As with other antihistaminic drugs, overdosage can produce the following symptoms: CNS depression accompanied by drowsiness (especially in adults), CNS stimulation and antimuscarinic effects (especially in children) including the following: excitation, ataxia, hallucinations, tonic or clonic spasms, mydriasis, dryness of the mouth, redness of the face, urine retention, fever and tachycardia. Blood hypotension is also possible. In its terminal phase, coma can be aggravated by cardiorespiratory colapse and death. There has been no report of a fatal outcome of Dimethindene overdosage.