3-Quinuclidinyl Benzilate Poisoning Workup

Updated: Feb 22, 2021
  • Author: Christopher P Holstege, MD; Chief Editor: Duane C Caneva, MD, MSc  more...
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Laboratory Studies

No rapid tests enable a health care provider to diagnose exposure to 3-quinuclidinyl benzilate (QNB). New testing techniques are being trialed, but are not readily available to treating clinicians. [5, 1, 6] Consider QNB if a number of persons arrive after an exposure to an unknown substance and manifest an anticholinergic syndrome.  

Obtaining a complete blood count, electrolytes, clotting studies, and kidney and liver function tests is reasonable in any person who potentially was exposed to a chemical warfare agent.

If the patient is markedly agitated or comatose, obtaining a urine myoglobin and/or creatine phosphokinase is warranted to exclude rhabdomyolysis. Hyperkalemia, hyperphosphatemia, and hypocalcemia may occur in association with rhabdomyolysis. The agitated patient also may develop an elevated lactate.

If QNB is considered in the differential, obtain extra blood and urine samples. Tests have been developed to confirm human exposure to QNB.

Disseminated intravascular coagulation is a potential complication in a patient with marked agitation and/or hyperthermia. Obtain clotting studies (eg, prothrombin time, activated partial thromboplastin time, international normalized ratio) in these patients. If clotting studies are elevated, then fibrinogen, fibrin split products, and a peripheral smear looking for evidence of hemolysis may be necessary.

Most of the QNB that enters the body is excreted by the kidneys, either as the parent compound or as metabolites, making urine the choice for detection. QNB undergoes hydrolysis to produce benzylic acid and 3-quinuclidinyl. A solid-phase extraction of the urine and isotope dilution in conjunction with gas chromatography/mass spectrometry (GC/MS) has been used for detection of QNB. [7]


Imaging Studies

See the list below:

  • A patient exposed to QNB who is comatose may be at risk for aspiration pneumonia; obtain a chest radiograph.

  • If the etiology of the altered mental status is uncertain, obtaining a head CT scan to exclude other intracranial processes is reasonable.



QNB is associated with sinus tachycardia. Patients exposed to QNB who have preexisting cardiac disease may be at risk for cardiac ischemia as their heart rates increase. Other anticholinergic agents are associated with QT prolongation, QRS widening, and various tachydysrhythmias. Obtain an ECG to exclude these potential problems.