UMEM Educational Pearls - Toxicology

Category: Toxicology

Title: Naloxone - Any Port In the Storm

Keywords: naloxone, opioids (PubMed Search)

Posted: 12/30/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
Click here to contact Fermin Barrueto, MD

Naloxone is the epitomy of an antidote with complete reversal of opioid toxicity within 60 seconds of administration. Remember your clinical endpoint should be respiratory effort. If you utilize "the vial" of either 0.4mg or 2mg and there is a higher probability of withdrawal and for acute lung injury. Here are some tips for administration:

1) IV Access: Try 0.1 mg or even 0.05 mg - anesthesiology typically doses naloxone in micrograms. Reversal is slower so you have to be patient. It is also not as dramatic so closely monitor respirations to see if you have improvement, that may be all that you get. These are probably patients that you don't want that awake anyways.

2) No IV Access: advantage of naloxone is it is bioavailable IV, intranasal and even by nebulizer.  Here you want the dose to be 0.4mg to start for intranasal. Nebulizer is difficult to measure and probably safe to start with 2mg in the nebulizer container.

There is a difference when you know it is an opioid overdose and are reversing apnea versus a diagnostic administration to determine if it is opioid toxicity. In the latter instance you can rationalize the large dose - just be ready and be sure you are not in line of the possible projectile vomiting.


Category: Toxicology

Title: Hydrofluoric Acid Burn

Keywords: HF (PubMed Search)

Posted: 12/23/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
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When you think of an acid or base causing a burn, you usually think of the local damage but there is one particular acid that causes systemic illness. Hydrofluoric Acid, found in your local Home Depot in brick/stone cleaning products, can cause severe illness despite a small total body surface area burn and exposure. A recent case report came out that illustrates how deadly HF can be. The reason is that this acid enters the body and chelates cations like calcium and potassium. The abstract is below but essentially hypocalcemia, hypokalemia leading to asystole 16hrs after exposure all from a 3% TBSA Burn - very impressive.


Background. Although hydrofluoric (HF) acid burns may cause extensive tissue damage, severe systemic toxicity is not common after mild dermal exposure. Case. A 36-year-old worker suffered a first-degree burn of 3% of his total body surface area as a result of being splashed on the right thigh with 20% HF acid. Immediate irrigation and topical use of calcium gluconate gel prevented local injury. However, the patient developed hypocalcemia and hypomagnesemia, hypokalemia, bradycardia, and eventually had asystole at 16 h post-exposure, which were unusual findings. He was successfully resuscitated by administration of calcium, magnesium, and potassium. Conclusion. This report highlights a late risk of HF acid dermal exposure.

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Category: Toxicology

Title: Fomepizole - Answer to Tox Pearl

Keywords: fomepizole, disulfiram (PubMed Search)

Posted: 12/17/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
Click here to contact Fermin Barrueto, MD

The answer was fomepizole would be the treatment for life-threatening disulfiram reaction. Blocks Alcohol Dehydrogenase and ironically prevent metabolism of ethanol and prolong intoxication.

I forgot how many see the pearls and the response was overwhelming. That was great and cost a me a little more. There were two winners:

Katie Baugher, PGY-1

Ari Keslter

Please email me how to best send you the gift certificate.


Category: Toxicology

Title: Can I drink Alcohol with this Med?

Keywords: disulfiram reaction (PubMed Search)

Posted: 12/16/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
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There are medications, if taken with ethanol, will cause a disulfiram reaction. This reaction results from inhibition of aldehyde dehydrogenase, the enzyme in ethanol metabolism that breaks acetaldehyde to acetic acid. The increase in acetaldehyde results in nausea, vomiting, diarrhea, flushing, palpitations and orthostatic hypotension. So if you prescribe a patient with any of these medications you must make certain to tell them NOT to drink any ethanol - that includes cough/cold preparations that have ethanol:

Antibiotics: Metronidazole(Flagyl), Trimethoprim-sulfamethoxazole (Bactrim)

Sulfonylureas: Chlorpropamide and tolbutamide

These have possible reactions: griseofulvin, quinacrine, procarbazine, phentolamine, nitrofurantoin


Bonus Question: $10 Starbuck's Gift Card for  first person that emails me with the answer to this question

What treatment could you give to someone suffering from a life threatening disulfiram reaction that biochemically should cure him? 

Category: Toxicology

Title: Toxin-Induced Causes of a Normal Anion Gap Metabolic Acidosis

Keywords: anion gap, metabolic acidosis (PubMed Search)

Posted: 12/8/2010 by Bryan Hayes, PharmD (Emailed: 12/9/2010) (Updated: 12/9/2010)
Click here to contact Bryan Hayes, PharmD

Most cases of normal anion gap metabolic acidosis result from either urinary (RTA) or gastrointestinal HCO3- losses (diarrhea).  A number of xenobiotics can also cause this disorder:

  1. Acetazolamide
  2. Acidifying Agents: Ammonium chloride, arginine hydrochloride, hydrochloric acid, lysine hydrochloride
  3. Cholestyramine
  4. Toluene
  5. Topiramate (Topamax)

Category: Toxicology

Title: Toxic Holiday Plants

Keywords: holly, berry, poinsettia, mistletoe, berries (PubMed Search)

Posted: 12/2/2010 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD

Toxic Holiday Plants

Of the three plants listed, which is NOT poisonous?

1.     Holly plant

2.     Poinsettia

3.     Mistletoe


Poinsettia plants were once thought to be very poisonous. Contrary to popular belief, poinsettias are safe to have in the home during the holidays.

Although there are reported cases of death with ingestion of Holly plants in older literature, recent experience shows gastrointestinal effects in small doses, and serious toxicity such as CNS depression in large ingestions.

Mistletoe ingestion of few of the berries would, at most, produce mild gastroenteritis; however, ingesting concentrated extracts of the plant, including the berries, may produce serious effects such as seizures, mental confusion, drowsiness, and hallucinations.

Happy holidays!

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As we eat our turkey today and the myth that we are tired because of the tryptophan content is propagated further - nothing to do with the 2000kcals that we just ate - I would like to share an interesting and controversial study. 

Use of stimulants and and sedatives by EM residents. Incidence is as follows:

In a study of 485 residents with 47% response rate:

Prescription Stimulants: 3.1%

Sleep Aids (all):  89%

Use of Nonbenzodiazepines (zolpidem): 14%

Use of Melatonin: 10%

Benzodiazepines: 9%

Difficult job with difficult hours. What is the appropriate medication or is there a medication that truly assists with performance? Are they doing harm to themselves? to patients?

Disrupted circadian rhythm, addiction tendencies and the hardship of a stressful nightshifts are the price we pay for this specialty. Awareness and education are needed for the residents as well as the attendings.

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Category: Toxicology

Title: How to Give Physostigmine

Keywords: anticholinergic, physostigmine (PubMed Search)

Posted: 11/18/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
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In the setting of a patient suffering from an anticholinergic overdose with hallucinations/agitation, it may be beneficial to administer the antidote: Physostigmine. Many hesitate simply because they have never administered before or there may be doubt in the diagnosis. Here is the skinny:

1) Anticholinergic OD seen in following meds: diphenhydramine (Benadryl), dimenhydrinate (Dramamine), scopolamine, benztropine (Cogentin), some plants like datura stromonium (thorn apple)

2) Physostigmine 1mg IV slowly over a REAL 5 min. Administer to fast and patient may seize. Maximum dose of 2mg IV.

3) Contraindications: suspicion of TCA OD (anectdotal and from old case report) - screening EKG should be done prior to administration of physostigmine. Also glaucoma, closed angle, obstructive uropathy.

Remember your clinical endpoint needs to be measurable, thus hallucinations and agitation should be reversed. No indication if the patient is only experiencing dry mouth or other more mild anticholinergic symptoms.

Category: Toxicology

Title: Hyperbaric Therapy for Hydrogen Peroxide Poisoning

Keywords: hydrogen peroxide, embolism, hyperbaric (PubMed Search)

Posted: 11/11/2010 by Bryan Hayes, PharmD (Updated: 6/16/2024)
Click here to contact Bryan Hayes, PharmD

  • Ingestion of concentrated hydrogen peroxide (H2O2) has been associated with venous and arterial gas embolic events, hemorrhagic gastritis, gastrointestinal bleeding, shock, and death.
  • Although H2O2 is generally considered a benign ingestion in low concentrations (OTC is 3%), case reports have described serious toxicity following high concentration exposures.
  • Hyperbaric oxygen (HBO) has been used with success in managing patients suffering from gas embolism with and without manifestations of ischemia.
  • A recent poison center case record review confirmed previous findings.
    • It identified 11 cases of portal gas embolism. In 10 cases 35% H2O2 was ingested and in 1 case 12% H2O2 was ingested. All abdominal CT scans demonstrated portal venous gas embolism in all cases. Hyperbaric treatment was successful in completely resolving all portal venous gas bubbles in nine patients (80%) and nearly resolving them in two others. Ten patients were able to be discharged home within 1 day, and one patient had a 3.5-day length of stay.
  • Bottom Line: In a patient with a history of hydrogen peroxide ingestion, have a low threshold for CT scan.  HBO therapy is an effective treatment modality.

French LK, et al. Hydrogen peroxide ingestion associated with portal venous gas and treatment with hyperbaric oxygen: a case series and review of the literature. Clinical Toxicology 2010;48:533–38.

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Category: Toxicology

Title: New anticoagulant: Dabigatran

Keywords: Dabigatran, warfarin, anticoagulant, thrombin inhibitor (PubMed Search)

Posted: 11/4/2010 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD


  • the first new ORAL anticoagulant in over 50 years
  • is a direct thrombin inhibitor
  • Indicated for reducing strokes and systemic embolism in patients with a fib
  • DOES NOT need monitoring and frequent dose adjustments
  • Has fewer drug and food interactions than warfarin
  • Costs about $8/day (more than the cost of warfarin PLUS monitoring)
  • Both warfarin and dabigatran have a similar OVERALL bleeding risk, but warfarin causes more intracranial bleeding and dabigatran more GI bleeding

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Category: Toxicology

Title: Mushroom Toxicity - Clinical Approach

Keywords: amanita, mushroom, poisoning (PubMed Search)

Posted: 10/28/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
Click here to contact Fermin Barrueto, MD

When a patient presents to the ED with a recent ingestion of a wild mushroom there are three very specific questions you must ask:

1) Exactly what time did you eat the mushroom?

2) Exactly what time did you begin vomiting/diarrhea/GI Sx in general?

3) Are there are more mushrooms that can be brought to ED for identification?

The reason the first two questions are critically important is it determines the total time of onset of toxicity. As a very general rule of thumb, delayed GI symptoms >6hrs is predictive of a possible lethal ingestion of a cyclopeptide containing mushroom like Amanita Phalloides. Immediate symptoms < 6hrs and even more so if within 2 hrs usually indicates ingestion of a nonlethal mushroom that causes GI distress (many mushrooms like Clitocybe nebularis)

Website with pics of the most poisonous mushrooms:

There is a saying:

"There are old mushroom pickers and wise mushroom pickers but no old and wise mushroom pickers"

Category: Toxicology

Title: Intralipid - It Works Video

Keywords: intralipid (PubMed Search)

Posted: 10/21/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
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Take a look at this link - an incredible video of how effective Intralipid can be:

Category: Toxicology

Title: Intralipid for Drug Overdose

Keywords: Intralipid, fat emulsion (PubMed Search)

Posted: 10/14/2010 by Bryan Hayes, PharmD (Updated: 6/16/2024)
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Emerging evidence supports using intravenous fat emulsion (Intralipid) therapy for various drug overdoses, particularly those that are lipophilic.  Within seconds to minutes of administration, toxic cardiovascular effects are reversed, including return of spontaneous circulation in cardiac arrest patients.  Central nervous system effects also tend to improve.

Lipophilic agents for which there has been success include:

  • Calcium channel blockers (verapamil, diltiazem, amlodipine)
  • Beta blockers
  • Bupropion
  • Quetiapine
  • Lamotrigine
  • Sertraline
  • TCA's
  • Diphenhydramine

Bottom line: Consider intralipid therapy early in the course of a hemodynamically unstable patient with suspected overdose.  Give a bolus of 1.5 mL/kg of 20% lipid emulsion over 1-2 minutes.

Category: Toxicology

Title: Shellfish Poisoning

Keywords: amnestic, neurotoxic, paralytic, shellfish (PubMed Search)

Posted: 9/30/2010 by Fermin Barrueto, MD
Click here to contact Fermin Barrueto, MD

Although we may not be able to eat as much shellfish after the oil spill, there are still some left that can cause some interesting toxicity here in the USA. Shellfish act as vectors for the bacteria, virus etc that produces toxin thus not specific to one species of shellfish. There is a map attached that shows where shellfish poisoning occurs most. In the picture CFP=ciguatera, PSP=Paralytic and ASP=AmnesticC. Surprising the distribution and it will be interesting how the oil spill affects the distribution. Treatment for all of these is supportive with no known antidote and incidence increases during Red Tide months:

Tox Fish Map

  • Paralytic Shellfish Poisoning
    • Saxitoxin, potent, heat-stable, blocks fast sodium channels
    • Symptoms: Paresthesias, weakness, bulbar symptoms, blindness and paralysis (30m-2hrs after meal)
  • Amnestic Shellfish Poisoning (my favorite excuse for why I forget my anniversary)
    • Domoic acid build up created from Nitzchia spp (a marine diatom). This causes release of gluatamate thus causing excitotoxic nerve damage.
    • 1987 outbreak in Canada saw GI Sx in 24 hrs followed by HA, SZ, memory loss - has been fatal


1009302022_US-toxinmap-circles-2009-web_86265.jpg (86 Kb)

Category: Toxicology

Title: Fentanyl Patch Abuse

Keywords: fentanyl (PubMed Search)

Posted: 9/16/2010 by Fermin Barrueto, MD (Updated: 9/18/2010)
Click here to contact Fermin Barrueto, MD

A fentanyl patch contains 100-fold more fentanyl in the reservoir than what is posted on the patch. For instance, 100mcg/hr patch will have over 10mg - thats milligrams - of fentanyl. This provides a rather large source for potential abuse. Overdose and deaths have occurred by patients in the following ways:

  1. Ingesting
  2. Placing in a cigarette and inhaling
  3. Inadvertent overdose by sleeping with an electric heating blanket and increasing absorption through the skin
  4. Steeping the patch in hot water
  5. Actually stealing the patches off of dead bodies in the morgue


It is the many

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Category: Toxicology

Title: Diagnosing Cyanide Poisoning with Lab Tests

Keywords: cyanide, lactate (PubMed Search)

Posted: 9/9/2010 by Bryan Hayes, PharmD (Updated: 6/16/2024)
Click here to contact Bryan Hayes, PharmD

In the setting of acute cyanide poisoning, it is virtually impossible to obtain a timely cyanide level to help assess toxicity.  However, there are two diagnostic tests that can help confirm your diagnosis.

  1. Anion gap metabolic acidosis with elevated lactate
  2. Narrowing of the venous-arterial PO2 gradient

Remember cyanide halts cellular respiration meaning the cells cannot utilize oxygen.  Therefore, the venous PO2 should be about the same as the arterial PO2.  The cells then switch to anaerobic metabolism, thereby producing lactate.

Category: Toxicology

Title: Epinephrine Digital Injections

Keywords: Epinephrine, epi-pen, digital block, finger, ischemia (PubMed Search)

Posted: 9/2/2010 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD

A recent study examined the effects of accidental digital epinephrine injection from auto-injectors. 127 cases with complete follow-up had the following effects:

  • no effects were reported in 10%
  • minor effects in 77%
  • moderate effects in 13%
  • major effects in 1 case

Pharmacologic vasodilators were used in 23%. Four patients had possible digital ischemia. All patients had complete resolution of symptoms, most within 2 hours. No patient was admitted, received hand surgery consultation, or had surgical care. 

Although this speaks for the safety of digital anesthesia using epinephrine, it underscores the importance of providing education to patients who are prescribed epinephrine auto-injectors.



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Category: Toxicology

Title: Caustic Exposures - Continued

Keywords: caustic (PubMed Search)

Posted: 8/26/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
Click here to contact Fermin Barrueto, MD

In a previous pearl we were discussing the need to perform EGD for any suicidal patient with a history of ingestion of a caustic to grade injury and assess chance of perforation and/or stricture formation. Suicidal patients are intentionally ingesting the caustic and can thus justify the risk/benefit ratio more easily than the pediatric unintentional ingestion. The concerned parent will bring the child in with a possible ingestion of a caustic. The container could be simply in the same room, spilled on the child and never be ingested. Even if ingested, the amount is less if the child tastes the caustic and will reflexively cause spitting. The literature is scant in regards to this type of patient but seems to point to this general algorithm:

Child displays 2 or more of the following symptoms there is enough evidence from case series that there will be a clinically signficant lesion found on EGD.

Vomiting, Drooling, Stridor, Presence of Oropharyngeal Burns

That being said, many clinicians would elect for EGD and assessment of airway with stridor alone. Do not be fooled into thinking if you see no oral lesions that there is no way the child ingested the caustic. Each case series showed a lack of correlation of physical exam findings to EGD findings.







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Category: Toxicology

Title: Sulfonylureas

Keywords: sulfonylureas,hypoglycemia (PubMed Search)

Posted: 8/19/2010 by Fermin Barrueto, MD (Updated: 6/16/2024)
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We will all get the patient presenting with low blood glucose on a regular basis. In general, barring any underlying infection, those who are insulin dependent can be corrected with IV dextrose and/or food and be discharged. Those on a sulfonylurea may experience repeated hypoglycemic episodes and require admission - perhaps even treatment with the antidote: octreotide.

Below is the duration of action and half-life of the sulfonylureas which illustrates the need for admission:

  • Chlorpropamide (Diabinase): Duration: 24-27hrs; t 1/2: 36hrs
  • Glipizide (Glucatrol): Duration 16-24hrs; t 1/2: 7hrs
  • Glipizide XL (Glucatrol XL): Duration 24hrs
  • Glyburide (Micronase others): Duration <24hrs; t 1/2 10hrs
  • Glimepride (Amaryl): Duration 16-24hrs; t1/2: 5-9hrs

Duration of action is the physiologic effect whereas the half-life is the pharmacokinetics of elimination of the drug. Often these two numbers are different for drugs. Do not let the half-life fool you into thinking it is safe to discharge a hypoglycemic patient on a sulfonylurea.

Category: Toxicology

Title: Cyproheptadine for Serotonin Syndrome

Keywords: serotonin syndrome, cyproheptadine (PubMed Search)

Posted: 8/12/2010 by Bryan Hayes, PharmD (Updated: 6/16/2024)
Click here to contact Bryan Hayes, PharmD

If benzodiazepines and supportive care fail to improve agitation and correct vital signs, several case reports indicate the successful use of cyproheptadine, an antihistamine with nonspecific antagonist effects at 5-HT1A and 5-HT2A receptors.

Cyproheptadine is available in 4 mg tablets or 2 mg/5 mL syrup. When administered as an antidote for serotonin syndrome, an initial dose of 8-12 mg is recommended, followed by 2 mg every two hours until clinical response is seen. Cyproheptadine is only available in an oral form, but it may be crushed and given through a nasogastric tube.

Cyproheptadine may lead to sedation, but this effect is consistent with the goals of management. It may also produce transient hypotension due to the reversal of serotonin-mediated increases in vascular tone. Such hypotension usually responds to IV fluids. Cyproheptadine is rated category B for safety in pregnancy by the FDA.