Rivastigmine for the Treatment of Hypoactive Anticholinergic Delirium and CNS Depression Associated Mainly With Clozapine Poisoning.

This prospective clinical study evaluates the efficacy of rivastigmine in treating the full spectrum of toxic anticholinergic delirium. The study encompasses both hyperactive (agitated) and hypoactive (depressed mental status/CNS depression) presentations, with a specific focus on the hypoactive variant. While anticholinergic toxicity is traditionally associated with agitation, this research highlights its role in causing hypoactive delirium and assesses how rivastigmine facilitates the recovery of consciousness and cognitive function.

Participants:

The study includes 100 patients (aged ≥18 years) with confirmed or clinically suspected toxic anticholinergic delirium-characterized by confusion, CNS depression, agitation, disorientation, and/or hallucinations-admitted to the Poison Control Center of Alexandria University Main Hospital (AUMH).

Clozapine and TCA Focus:

A significant majority of the study population (approximately 90%) consists of clozapine toxicity cases, presenting primarily with hypoactive delirium and CNS depression. Furthermore, the study explores the safety and efficacy of rivastigmine in cases of Tricyclic Antidepressant (TCA) toxicity. Although the use of acetylcholinesterase inhibitors in TCA poisoning has traditionally been approached with caution due to cardiotoxicity concerns, this research evaluates the potential of rivastigmine to safely reverse TCA-induced CNS depression without adverse cardiac events, potentially challenging existing clinical conventions.

Intervention Protocol:

Administration: An initial enteral dose of 6 mg is administered. In patients with a low Glasgow Coma Scale (GCS) score or those unable to tolerate oral intake, the medication is administered via a Nasogastric Tube (NGT) to ensure rapid delivery.

Dosing: Additional 6 mg doses are administered every 2 hours if CNS symptoms persist.

Assessment \& Resolution:

Clinical evaluation includes monitoring awareness, orientation, and the return of consciousness. The Glasgow Coma Scale (GCS) and Richmond Agitation-Sedation Scale (RASS) are utilized to measure consciousness and arousal at baseline, and at 2, 6, and 8 hours post-administration. Resolution is defined as the restoration of normal consciousness and appropriate interaction. The study also monitors the resolution of peripheral antimuscarinic features, such as the normalization of heart rate.