Atropine

In brain death, 1 amp of atropine (1 mg) IV should not affect the heart rate due to the absence of vagal tone (the normal response to atropine of increased heart rate rules out brain death, but the absence of the response is not helpful since some conditions such as Guillain-Barré may blunt the response). Systemic atropine in usual doses causes slight pupillary dilatation but does not eliminate reaction to light (therefore, to eliminate uncertainty, it is prudent to examine the pupils before giving the atropine).

Akça D, Güneş A, Karaçetin G. Use of Sublingual Atropine Drops in Clozapine-Associated Sialorrhea in an Adolescent Patient: A Case Report. J Clin Psychopharmacol. 2022 Oct 17. doi: 10.1097/JCP.0000000000001616. Epub ahead of print. PMID: 36251377.