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Treatment of anticholinergic side effects

Anticholinergic-induced mydriasis can be reversed by using thimoxamine 0.5% (Smith, 1971). To overcome constipation because of continued treatment with anticholinergic drugs a change in diet, addition of roughage, lactulose 5-30 ml daily, ispaghula husk 3-5 gm daily or other laxatives can be tried. When the anticholinergic side effects are primarily peripheral, neostigmine can be tried which does not penetrate the blood brain barrier. It reverses the peripheral anticholinergic effects and does not increase the severity of EPS or parkinsonism.

Mental, behavioural and cognitive symptoms usually recover without incidence within 2 to 7 days of anticholinergic withdrawal, although physostigmine 2 mg subcutaneously has been given to speed recovery (El-Yousef et al, 1972). The anticholinergic blockade can be reversed by physostigmine 1-2 mg subcutaneously (Duvoisin & Katz, 1968) and sodium thiopentone can be given if excitement predominates. Oxygen may be needed to assist ventilation. Paradoxically chlorpromazine which may enhance toxic effects of anticholinergics has been used in cases of atropine poisoning (Wood & Haq, 1971) It also relieves psychotic symptoms in anticholinergic poisoning.