Anticholinergic agents allergic reactions

Several of the older generation antihistamines are used exclusively for situations that do not involve an allergic reaction. For example, some demonstrate significant antiemetic, antimotion sickness, antiparkinsonian, antitussive, and local anesthetic actions (some Hj antagonists are more potent than procaine). They can be found in many OTC products, particularly for the relief of symptoms from the common cold and allergies, as well as by prescription. The effectiveness of the agents in the treatment of motion sickness and Parkinson s disease may be attributed to their anticholinergic actions. 

A report of three cases (126) has suggested that central cholinergic overactivity is implicated, and that atropine sulfate 3 mg/day or synthetic anticholinergic agents (such as benzatropine mesylate 4 mg/day) ameliorate withdrawal symptoms within a few hours. The authors suggested that this technique may be especially useful in patients in whom tricyclic antidepressants must be abruptly withdrawn because of allergic or idiosyncratic reactions. 

Sympathomimetics are used to produce mydriasis for ophthalmoscopic evaluation mydriasis is not maximal, as with the anticholinergic mydriatics, but especially in younger patients sympathomimetic mydriasis proves quite effective and causes little or no reduction in accommodation. Sympathomimetic agents are also used as vasoconstrictors in surgical procedures, for symptomatic relief or allergic reactions and hyperaemia of the conjunctiva, and to lower intra-ocular pressure in glaucoma. 

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