UMEM Educational Pearls - Toxicology

Category: Toxicology

Title: Dexmedetomidine (Precedex)

Keywords: sedation, dexmedetomidine (PubMed Search)

Posted: 4/26/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Dexmedetomidine is an alpha2-agonist that has a similiar mechanism of action to clonidine. Short half-life and no respiratory depression make it possibly more effective than propofol in procedural sedation. Cost/Availability are the biggest barriers. Transient bradycardia is also possible but the actual incidence  of clinically significant bradycardia is not yet elucidated.

I am still awaiting the first emergency department study looking at dexmedetomidine for procedural sedation.

A recent article actually brought up the possibility of utilizing it intranasally which could have some tantalizing pediatric applications.

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Category: Toxicology

Title: Maternal Opioid Use and Breast-Fed Infants

Keywords: Opioid, breastfeeding, breast milk, newborn, infant (PubMed Search)

Posted: 4/5/2012 by Bryan Hayes, PharmD (Emailed: 4/12/2012) (Updated: 4/12/2012)
Click here to contact Bryan Hayes, PharmD

Over the last few decades, the rate of breastfeeding has increased steadily in the developed countries of the world. During this time, opioid  use in the general population has steadily increased as well. Despite this, clinicians remain unclear whether opioid use is safe during breastfeeding.

A recent article reviewed the production of breast milk, the transfer of xenobiotics from blood to milk, the characteristics that alter xenobiotic breast-milk concentrations, and the evidence of specific common opioids and infant toxicity.
 
Conclusion: The short-term maternal use of prescription opioids is usually safe and infrequently presents a hazard to the newborn.
 
 
Bonus app suggestion:
Continuing with the theme of the week, here is a nifty, free tox app for the iPhone called Emergency Toxicology. It is rudimentary and pretty basic, but it is a good starting tool.
http://itunes.apple.com/us/app/emergency-toxicology/id504893108?mt=8
iPhone Screenshot 1

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Protamine for enoxaparin overdose

  • Protamine may be used to treat severe cases of hemorrhage in enoxaparin overdose
  • Protamine reverses the prolonged aPTT, but fails to completely reverse the anti-Xa effect (reverses about 60%)
  • Administer protamine by slow IV to equal the dose of enoxaparin injected: (1:1 ratio) 
  • if < 8 hours after last dose enoxaparin, give 1 mg protamine per 1 mg enoxaparin;
  • if 8-12 hours after last dose enoxaparin, give 0.5 mg protamine per 1 mg enoxaparin;
  • if >12 hours after last dose of enoxaparin,  protamine is not required

Category: Toxicology

Title: Nebulized epinephrine for Smoke Inhalation

Keywords: epinephrine, carbon monoxide, smoke inhalation (PubMed Search)

Posted: 3/29/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Animal studies can pave the way for new clinical treatment modalities. In the setting of lung injury due to smoke inhalation, one of the problems (if you can get the ET tube in) are the elevated ventilatory pressures due to the massive edema. In this sheep model of smoke inhalation, nebulized epinephrine improved ventilatory pressures, PaO2/FiO2 ratio and pulmonary shunting.

We may have these sheep to thank for this new treatment.

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Category: Toxicology

Title: Had enough of coumadin and clopidogrel wannabe's?

Keywords: ticagrelor, brillinta, xarelto, pradaxa (PubMed Search)

Posted: 3/15/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Coumadin Wannabe's - have indication non-valvular atrial fibrillation

1) Dabigatran (Pradaxa) 

2) Rivaroxaban (Xarelto)

Clopidogrel Wannabe's - both are antiplatelets

1) Ticagrelor (Brilinta)

2) Prasugrel (Effient)

If you were looking for the first case reports of lethal hemorrhage due to pradaxa that could not be reversed - look no further. One patient fall from standing dies from ICH and another death in a spine trauma patient on pradaxa. I am waiting for the first epidural hematoma due to pradaxa, xarelto, etc in ED. Watch out! :

 

  1: Garber ST, Sivakumar W, Schmidt RH. Neurosurgical complications of direct  thrombin inhibitors-catastrophic hemorrhage after mild traumatic brain injury in  a patient receiving dabigatran. J Neurosurg. 2012 Mar 6.       2: Truumees E, Gaudu T, Dieterichs C, Geck M, Stokes J. Epidural Hematoma &  Intra-operative Hemorrhage in a Spine Trauma Patient on Pradaxa® [Dabigatran].  Spine (Phila Pa 1976). 2012 Feb 16. 

 


Category: Toxicology

Title: Pressure Immobilization for Crotalid snake envenomation

Keywords: crotalinae, snake, pressure immobilization, envenomation (PubMed Search)

Posted: 3/4/2012 by Bryan Hayes, PharmD (Emailed: 3/8/2012) (Updated: 3/8/2012)
Click here to contact Bryan Hayes, PharmD

Pressure immobilization involves wrapping the entire extremity with a bandage and then immobilizing the extremity with a splint. It is a technique routinely employed in the pre-hospital management of neurotoxic snakes in Australia.

A position statement was recently published by several international toxicology societies regarding the utility of pressure immobilization after North American Crotalinae snake envenomation (e.g., Copperheads, Timber rattlesnakes, Cottonmouths).

"Available evidence fails to establish the efficacy of pressure immobilization in humans, but indicates the possibility of serious adverse events arising from its use. The use of pressure immobilization for the pre-hospital treatment of North American Crotalinae envenomation is NOT recommended."

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Category: Toxicology

Title: Octreotide for sulfonylurea overdose- updated

Keywords: Octreotide, sulfonylurea, glucose, insulin (PubMed Search)

Posted: 3/1/2012 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD

 

  • Sulfonyurea overdose is associated with hypoglycemia, which may be delayed and prolonged.
  • Treatment with dextrose results in hyperglycemia, which potentiates insulin release from the pancreas, resulting in recurrent hypoglycemia.
  • Octreotide mimics somatostatin, which suppresses the secretion of glucagon and insulin, among others.
  • Octreotide binds with somatostatin receptors, closing calcium channels, preventing the influx of calcium and subsequent insulin release.
  • The dose is 100 mcg SUBCUTANEOUSLY, repeated every 8 hours as needed.

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Category: Toxicology

Title: IM Midazolam vs IV Lorazepam for Seizure Pre-Hospital

Keywords: midazolam, lorazepam (PubMed Search)

Posted: 2/23/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

You have seen the study comparing diazepam to lorazepam IV for the cessation of seizures. Lorazepam one that one. Now, for prehospital status epilepticus midazolam IM went head to head with IV lorazepam to see which would stop seizure more quickly.

This study was more about the practicality of starting an IV than it was of the pharmacokinetics or onset of action of a particular benzodiazepine. It was a large enough study to warrant publication in New Engl J Med last month and is worth noting.

Subjects whose seizures ceased before ED arrival (median):

Time to active treatment: 1.2 min IM Midazolam group;  4.8 min IV Lorazepam group

Median times active treatment to cessation of SZ:  3.3 min IM Midazolam and 1.6 min IV Lorazepam

Safety was equal in both groups. This study validates EMS initiating therapy with IM midazolam for the cessation of seizures while intravenous access is being attempted. 

 

 

 

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Category: Toxicology

Title: Drug Rash with Eosinophilia and Systemic Symptoms (DRESS)

Keywords: DRESS, anticonvulsant, eosinophilia, phenytoin, carbamazepine (PubMed Search)

Posted: 2/7/2012 by Bryan Hayes, PharmD (Emailed: 2/9/2012) (Updated: 2/19/2012)
Click here to contact Bryan Hayes, PharmD

  • Drug rash with eosinophilia and systemic symptoms (DRESS) syndrome, previously named “anticonvulsant hypersensitivity syndrome,” is a severe adverse drug reaction which occurs in approximately 1 of every 1,000–10,000 uses of anticonvulsants.

  • Characterized by triad of fever, rash, and internal organ involvement.

  • Usually involves aromatic anticonvulsants such as phenytoin, carbamazepine, phenobarbital, primidone, lamotrigine, and possibly oxcarbazepine.

  • DRESS occurs most frequently within the first 2 months of therapy and is not related to dose or serum concentration.

  • Treatment includes prompt discontinuation of the offending agent. Patients should be admitted to the hospital and receive methylprednisolone 0.5–1 mg/kg/d divided in four doses. Other promising therapies include use of IVIG.

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Category: Toxicology

Title: Succinylcholine

Keywords: paralytic, hyperkalemia, succinylcholine (PubMed Search)

Posted: 1/26/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

As we go through the problems of national drug shortages it is important to remember the old drugs but to also remember why they became old and seldom used drugs. Prime example is many hospitals are beginning to develop shortages of rocuronium - the nondepolarizing paralytic that has a fast onset. This shortage has caused many to switch back to succinylcholine. The following case report should serve as reminder of how succinylcholine - due to its depolarizing nature and fasciculations - can cause a transient but significant hyperkalemia.

 

 

Succinylcholine-induced Hyperkalemia in a Patient with Multiple Sclerosis 
The Journal of Emergency Medicine, 12/13/2011

Levine M et al. – This case report describes a 38–year–old woman with multiple sclerosis who developed life–threatening hyperkalemia after the administration of succinylcholine during rapid sequence intubation. This case highlights the potential for iatrogenic hyperkalemia after succinylcholine in patients with neurologic diseases, including multiple sclerosis.





Category: Toxicology

Title: Pradaxa - Watch out

Keywords: pradaxa, myocardial infarction (PubMed Search)

Posted: 1/19/2012 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Never be the first or last person to use a drug 

Vioxx was once touted to be the drug that would be the new standard for anti-inflammatories until it was found to increase your chance of MI by 33% and cause hypertension.

Dabigatran was recently pulled from Japan markets and now is dealing with an impressive meta-analysis by Uchino et al. It showed that dabigatran was significantly associated with higher risk of MI or ACS than other agents.

Control arms (included warfarin, enoxaparin or placebo): MI rate 83 per 10,514

Dabigatran arms: MI rate 237 per 20,000

OR 1.33; 95% CI, 1.03-1.71; p=0.03

The rush for what is perceived as a panaceae for all that is wrong with coumadin could actually cause an MI while it tries to prevent a stroke in nonvalvular a-fib.

Look at the study and decide for yourself and remember Vioxx:

http://archinte.ama-assn.org/cgi/content/full/archinternmed.2011.1666v1


Category: Toxicology

Title: Buprenorphine Poisoning in Children (submitted by Ashley Strobel, MD)

Keywords: buprenorphine, Suboxone, overdose, children (PubMed Search)

Posted: 1/10/2012 by Bryan Hayes, PharmD (Emailed: 1/12/2012) (Updated: 1/12/2012)
Click here to contact Bryan Hayes, PharmD

  • Suboxone = buprenorphine and naloxone in a 4:1 ratio, respectively. Formulated in 2 mg or 8mg tablets and film.

  • Buprenorphine acts as a partial agonist on the mu receptor and an antagonist at the kappa receptor.

  • If > 2 mg are ingested or age < 2 years old, these patients should be evaluated in an ED as ALL children with > 4 mg ingestion had symptoms.

  • There is a ceiling effect with respiratory depression however no ceiling with analgesia. This gives buprenorphine a better safety profile compared to methadone.

  • Onset of symptoms is about an hour and onset of respiratory depression is about 2-3 hours.

  • Increased doses of naloxone starting at 0.1 mg/kg may be needed to overcome high receptor affinity of buprenorphine. Remember, most children are opioid-naive and will not experience withdrawal symptoms. Repeat doses of naloxone and even infusions may be needed.

  • In the ED, a minimum of 6 hours observation is necessary. If no clinical effects are noted at 6 hours the patient can safely be discharged, although one small case series recommended 24 hours observation.

  • Unintentional overdose is common in toddlers, so advise family to keep prescriptions including family pet prescriptions locked (buprenorphine in the IV form is used for veterinary pain control).

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Category: Toxicology

Title: Rivaroxaban (Xarelto) - Another Pradaxa?

Keywords: pradaxa, xarelto (PubMed Search)

Posted: 12/29/2011 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Another great example of the generic drug name being so difficult to pronounce you have no choice but to say - Xarelto. The drug touts ease of use and no need for hematologic monitoring like Pradaxa. This drug has the same indication for stroke prevention in nonvalvular atrial fibrillation. It also is being used in DVT prophylaxis in hip and knee surgeries.

Differences:

- Selective Factor Xa inhibitor unlike Pradaxa which is a competetive direct thrombin inhibitor

- Once a day dosing instead of twice a day for Pradaxa

Same concerns:

- No real reversal but can use FFP in a pinch

- Recommend waiting 24 hrs DC med to perform surgical procedure - this includes LP. I am personally waiting for the first case report of LP performed in ED on a patient taking either Xarelto or Pradaxa with subsequent epidural hematoma. Someone is bound to miss this on the med list. Be careful.

Even if your hospital has not added it to its formulary, you will see patients on this drug in the ED.


Category: Toxicology

Title: Hydrogen Peroxide

Keywords: hydrogen peroxide (PubMed Search)

Posted: 12/22/2011 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Generally H2O2 is available OTC at a concentration of 3-9% and used as an antiseptic. Toxicity is by two methods: local irritation like a caustic and gas formation - both directly correlating with the % concentration. Some interesting findings have occurred with this ingestion including:

1) Portal vein gas seen on CT

2) Arterialization of O2 resulting in CVA

3) Encephalopathy with cortical visual impairment

4) MRI showing b/l hemispheric CVAs

Even use of 3% H2O2 for wound irrgation has caused subcutaneous emphysema and O2 emboli.

Treatment: XR/CT/MRI may detect gas, if present in RV should be placed in Tredelenburg and carefully aspirated through a central venous catheter. Anectdotal case reports have used HBO therapy when patients were critically ill.(1)

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Category: Toxicology

Title: Warfarin management of ED patients

Keywords: warfarin, INR (PubMed Search)

Posted: 11/29/2011 by Bryan Hayes, PharmD (Emailed: 12/8/2011) (Updated: 12/8/2011)
Click here to contact Bryan Hayes, PharmD

A recent study highlighted the challenges we face managing ED patients on warfarin therapy. Some key observations about how we're doing: 

  • Only 71% of patients on warfarin had an INR checked
  • Nontherapeutic INRs were recorded for 49%; ED providers intervened to address these results in 21% of cases
  • 71% of patients with a supratherapeutic INR received an intervention compared with 9% of patients with a subtherapeutic INR
  • 30% of patients received or were prescribed potentially interacting medications
  • Recommendations for specific anticoagulation follow-up were documented for only 19% of all patients

Literature continues to show warfarin is the most dangerous medication for our patients. Meticulous monitoring and follow up will help us potentially avoid serious interactions and adverse events.

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Category: Toxicology

Title: High dose insulin in cardiogenic shock

Keywords: Insulin,beta blockers,calcium channel blockers (PubMed Search)

Posted: 12/1/2011 by Ellen Lemkin, MD, PharmD
Click here to contact Ellen Lemkin, MD, PharmD

High dose insulin is recommended in treatment of beta-blocker and calcium channel blocker overdose. In a recent observational case series of cardiogenic shock, high dose insulin was evaluated for efficacy and safety.

 
The overdoses were primarily calcium channel and beta blockers, but included other agents
like tricyclic antidepressants.
  • Insulin doses were given at a maximum of 10 units/kg/hour.
  • Seven patients who were on vasopressors when enrolled were tapered off when placed on high dose insulin.
  • 11/12 patients lived and were discharged from the hospital.
  • Adverse effects included hypoglycemia (19 events) and hypokalemia (8).
Bottom line: High dose insulin, when used in doses up to 10 units/kg/hr allows avoidance of vasopressors, and appears to be effective in the treatment of toxin induced shock in this small case series.

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Category: Toxicology

Title: Toxic Epidermal Necrolysis

Keywords: Toxic, epidermal, necrolysis (PubMed Search)

Posted: 11/17/2011 by Fermin Barrueto, MD
Click here to contact Fermin Barrueto, MD

TEN is a rare, life-threatening dermatologic emergency characterized initially by erythema and tenderness. It is followed by a severe exfoliation that resembles a severe burn patient. Classically occurs within days of the exposure of the drug. Nikolsky's sign may be present - not pathognomonic.

The following is a short list of medications that can cause this lethal reaction:

allopurinol, bactrim, nitrofurantoin, NSAIDs, penicillin, phenytoin, lamotrigine, sulfasalazine

Treatment: transfer to a burn center may be needed, steroids are not generally recommended however immunomodulators are beginning to show promise - IVIG, cyclosporine and cyclophosphamide

 

See pic that is attached for example of the sloughing


Attachments

TENPic.jpg (95 Kb)


Category: Toxicology

Title: Medication Causes of Idiopathic Intracranial Hypertension

Keywords: idiopathic intracranial hypertension, pseudotumor cerebri, tetracycline, vitamin a (PubMed Search)

Posted: 10/11/2011 by Bryan Hayes, PharmD (Emailed: 11/10/2011) (Updated: 11/10/2011)
Click here to contact Bryan Hayes, PharmD

Several medications have been linked to causing idiopathic intracranial hypertension (pseudotumor cerebri). Be sure to record an accurate medication history in patients you suspect of having this diagnosis.

  • Excessive doses of vitamin A
    • Other retinoids too: retinol, isotretinoin, and tretinoin
  • Tetracyclines (tetracycline, doxycycline, minocycline)
  • Growth hormone

Withdrawal of the offending agent will generally resolve the symptoms.


Category: Toxicology

Title: Salicylate Toxicity- Mechanism

Keywords: salicylate, aspirin, alkalosis, acidosis (PubMed Search)

Posted: 11/3/2011 by Ellen Lemkin, MD, PharmD (Updated: 1/18/2022)
Click here to contact Ellen Lemkin, MD, PharmD

Salicylates:

  • stimulate the respiratory center in the brainstem, causing respiratory alkalosis
  • interfere with the Krebs cycle, limiting ATP production, leading to an anaerobic metabolism
  • uncouple oxidative phosphorylation, causing accumulation of pyruvic and lactic acid and heat production, resulting in acidosis and hyperthermia
  • increase fatty acid metabolism, generating ketone bodies

Overall, this results in a mixed respiratory alkalosis and metabolic acidosis. 

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Category: Toxicology

Title: Methotrexate

Keywords: overdose, methotrexate (PubMed Search)

Posted: 10/27/2011 by Fermin Barrueto, MD (Updated: 1/18/2022)
Click here to contact Fermin Barrueto, MD

Methotrexate is a chemotherapeutic that is utilized in non-Hodgkin lymphoma and breast CA. It is also used as an immunosuppressant for rheumatoid arthritis and psoriasis. Finally, we see it used in the ED for the treatment of ectopic pregnancy. Overdose, often unintentional, can have a lethal outcome.

Toxicity: LFTs rise, N/V, stomatitis, mucositis, leukopenia, thrombocytopenia, renal failure

Antidote: Leukovorin (Folinic Acid)

Other Tx: Carboxypeptidase G2, Charcoal Hemoperfusion, HD (possible)