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Opioids/Benzodiazepines Poisoning Workup

  • Author: Christopher P Holstege, MD; Chief Editor: Zygmunt F Dembek, PhD, MPH, MS, LHD  more...
Updated: Sep 08, 2015

Laboratory Studies

The use of laboratory studies in the treatment of patients potentially exposed to opioid or benzodiazepine incapacitating agents should initially focus on the potential complications associated with those sedatives. Additional laboratory tests can also be conducted in an attempt to identify the diagnosis of the incapacitating agent if the specific agent is unknown to the clinicians.

Rapid urine drug screenings (immunoassays) are available and may assist health care professionals in making a diagnosis. However, these immunoassays do have a number of limitations. Opioid immunoassays are directed toward morphine. Many synthetic opioids, such as fentanyl, show no cross-reactivity with these assays. Testing for benzodiazepines is complicated because numerous benzodiazepines have substantially different structures. Results may be positive for diazepam, but negative for other benzodiazepines (eg, clonazepam).

Performing a complete blood count, electrolyte tests, clotting studies, and renal and liver function tests is reasonable in any person who has potentially been exposed to an incapacitating agent.

If the patient is comatose, performing a urine myoglobin and/or creatine phosphokinase test is warranted to exclude rhabdomyolysis. Hyperkalemia, hyperphosphatemia, and hypocalcemia may occur in association with rhabdomyolysis. The lactate level may also be elevated in these patients.

If the incapacitating agent is unknown, obtain extra blood and urine samples. Subsequent testing can be performed to confirm the causative agent.


Imaging Studies

See the list below:

  • A patient who has potentially been exposed to an opioid or a benzodiazepine incapacitating agent and who is comatose may be at risk for aspiration pneumonia. Obtain a chest radiograph.
  • If the etiology of a patient's altered mental status is uncertain, performing a head CT scan to exclude other intracranial processes is reasonable.

Other Tests

Both opioids and benzodiazepines may be associated with bradycardia. However, stress occurring in response to a situation associated with an exposure to aerosolized opioids or benzodiazepines may lead to tachycardia. Patients who are exposed to these agents and have preexisting cardiac disease may be at risk for cardiac ischemia. Perform an ECG to exclude these potential problems.

Contributor Information and Disclosures

Christopher P Holstege, MD Professor of Emergency Medicine and Pediatrics, University of Virginia School of Medicine; Chief, Division of Medical Toxicology, Center of Clinical Toxicology; Medical Director, Blue Ridge Poison Center

Christopher P Holstege, MD is a member of the following medical societies: American Academy of Clinical Toxicology, Medical Society of Virginia, Society of Toxicology, Wilderness Medical Society, European Association of Poisons Centres and Clinical Toxicologists, American Academy of Emergency Medicine, American College of Emergency Physicians, American College of Medical Toxicology, Society for Academic Emergency Medicine

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Chief Editor

Zygmunt F Dembek, PhD, MPH, MS, LHD Associate Professor, Department of Military and Emergency Medicine, Adjunct Assistant Professor, Department of Preventive Medicine and Biometrics, Uniformed Services University of the Health Sciences, F Edward Hebert School of Medicine

Zygmunt F Dembek, PhD, MPH, MS, LHD is a member of the following medical societies: American Chemical Society, New York Academy of Sciences

Disclosure: Nothing to disclose.

Additional Contributors

Suzanne White, MD Medical Director, Regional Poison Control Center at Children's Hospital, Program Director of Medical Toxicology, Associate Professor, Departments of Emergency Medicine and Pediatrics, Wayne State University School of Medicine

Suzanne White, MD is a member of the following medical societies: Alpha Omega Alpha, American Academy of Clinical Toxicology, American College of Epidemiology, American College of Medical Toxicology, American Medical Association, Michigan State Medical Society

Disclosure: Nothing to disclose.

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