[1][2] These agents inhibit the parasympathetic nervous system by selectively blocking the binding of ACh to its receptor in nerve cells.
[10] Effects of anticholinergic drugs include: Clinically the most significant feature is delirium, particularly in the elderly, who are most likely to be affected by the toxidrome.
Wider use is discouraged due to the significant side effects related to cholinergic excess including seizures, muscle weakness, bradycardia, bronchoconstriction, lacrimation, salivation, bronchorrhea, vomiting, and diarrhea.
Caffeine (although an adenosine receptor antagonist) can counteract the anticholinergic symptoms by reducing sedation and increasing acetylcholine activity, thereby causing alertness and arousal.
[32] Examples include hydrocodone/homatropine (Tussigon, Hydromet, Hycodan), diphenoxylate/atropine (Lomotil), and hydrocodone polistirex/chlorpheniramine polistirex (Tussionex Pennkinetic, TussiCaps).
However, it is noted that opioid/antihistamine combinations are used clinically for their synergistic effect in the management of pain and maintenance of dissociative anesthesia (sedation) in such preparations as meperidine/promethazine (Mepergan) and dipipanone/cyclizine (Diconal), which act as strong anticholinergic agents.