UMEM Educational Pearls - By Ellen Lemkin

Category: Toxicology

Title: Carbon Monoxide (CO) Poisoning

Keywords: carbon monoxide, CO, hyperbarics, HBO (PubMed Search)

Posted: 12/4/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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CO is formed from the incomplete combustion of carbon materials, eg. fires, stoves, portable heaters CO reversibly binds hemoglobin, producing carboxyhemoglobin (HbCO). This causes oxygen to bind more tightly to hemoglobin, releasing less in the tissues. Because of this, it affects the organs with the highest oxygen requirements most profoundly (eg. brain and heart).

Symptoms are mainly neurological and cardiovascular, but may include a wide variety of non-specific symptoms. The initial symptoms of CO poisoning may include headache and flu-like illness progressing to confusion, agitation, lethargy, seizures and coma.

Place patients on 100% oxygen to decrease the half-life of HbCO. Though controversial, HBO therapy is thought to decrease the incidence of neurologic sequelae. HBO therapy should be considered for patients with a HbCO level above 20%, severely symptomatic patients with lower levels, and pregnant patients. Remember that pulse oximetry will not be accurate.

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Category: Toxicology

Title: Salvia Divinorum

Keywords: Drugs of abuse, salvia, sage (PubMed Search)

Posted: 11/6/2008 by Ellen Lemkin, MD, PharmD (Emailed: 11/7/2008) (Updated: 4/13/2024)
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This is a psychoactive herb which can induce strong dissociative effects by stimulation of the kappa receptor. It has become increasingly well known and available in modern culture, and popularized by YouTube Salvia (also known as Sage, Diviner's Sage, Magic Mint, or Sally D) is usually smoked, but can be chewed or ingested.

The high it produces is very intense, but lasts only approximately 10 minutes. Currently many states have enacted legislation against it, including Fla, IL, KA, MI, MO, ND, OK and VA, but it is available over the internet.


The following video demonstrates clinical effects of drug.
Although it is amusing, this is not meant to condone use.

(if you can not view the embeded video here is the link)

Category: Toxicology


Keywords: ICP, intracranial pressure, antihypertensive, nitroprusside, nitroglycerin, hydralazine (PubMed Search)

Posted: 10/2/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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Several antihypertensive agents raise intracranial pressure. Normal cerebral blood flow (CBF) is constant within normal cerebral perfusion pressure (CPP) ranges, recalling that CPP=MAP-ICP.

If CPP is outside the range in which autoregulation occurs, e.g. due to a structural lesion, ischemic stroke, or head trauma, CBF decreases and can adversely affect the patient.

  • Nitroprusside
    • Vasodilates both cerebral arteries and veins, increasing ICP
    • Inhibits the normal vasoconstrictive response to hypocapnia
  • Nitroglycerin
    • Causes cerebral venodilation, increasing ICP
    • Impairs vasodilatory response to hypercapnia
  • Hydralazine (varying effects)
    • Vasodilates cerebral arteries > cerebral veins
    • Impairs cerebral autoregulation
  • Nicardipine
    • Other calcium channel blockers increase ICP by vasodilating arteries
    • Has been used to treat vasospasm in SAH
    • Increases cerebral blood flow in patients with SAH and acute stroke

In patients with ischemic stroke or intracerebral pathology, labetalol or esmolol may be used to lower blood pressure without raising ICP. Nicardipine is recommended for use in patients with ischemic stroke or SAH but not in patients with brain injury

If the patient has NO structural abnormalities, but has hypertensive encephalopathy, nitroglycerin, nitroprusside, labetalol, esmolol, or nicardipine may be used.

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Category: Toxicology

Title: Topical Lidocaine for Local Anesthesia

Keywords: Lidocaine, pediatrics, anesthesia (PubMed Search)

Posted: 9/4/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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Topical Lidocaine for local anesthesia

  • Zingo® (lidocaine 0.5 mg powder) is a new product designed to reduce pain with IV access
  • Onset of action 1-3 minutes (compared with 30 minutes with lidocaine/prilocaine creams (EMLA®), liposomal lidocaine 4% (LMX®), or lidocaine/tetracaine patches (Synera®)
  • Duration of action is only 10 minutes (procedure must be done in 10 minutes)
  • Uses helium to forcefully deliver drug into the skin
  • Looks like a marker that you press down and you hear a loud pop
  • Cost $20 per dose
  • Approved for children 3-18 years of age


Disclosure: I have no financial or invested interest in the product or the company.

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Category: Toxicology

Title: Disulfiram-like reactions

Keywords: drug interactions, disulfiram, bactrim, tinidazole, metronidazole (PubMed Search)

Posted: 8/7/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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Alcohol-Drug Interactions

  • There are a number of medications that produce the disulfiram-like reaction when ingested with alcohol.
  • The disulfiram reaction is a very uncomfortable reaction characterized by severe flushing, and may be accompanied by tachycardia and hypotension.
  • Although we always think of metronidazole, there have been well described cases of bactrim causing this reaction.
  • Tinidazole, a new antiprotozoal used in the treatment of trichomonas, causes this as well.
  • Patients should be advised to avoid alcohol for 24 hours after metronidazole, and 72 hours after bactrim and tinidazole.

Other common medications that produce this reaction:

1. Sulfonylureas: chlorpropamide, tolbutamide, glyburide

2. Cardiovascular medications: Isosorbide dinitrate, nitroglycerin

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Category: Toxicology

Title: Trends in Drug Abuse

Keywords: drugs of abuse, heroin (PubMed Search)

Posted: 7/3/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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  • "Pharming" is prescription drug abuse
  • Teens will take medications from their home medicine cabinets, mix them in bags together indiscriminately and make "trail mix" to pass around parties
  • "Cheese" is a combination of heroin with cough and cold preparations. The heroin concentration in cheese is typically between 2-8% compared to 30% found in black tar heroin, and is considered "starter heroin"

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Category: Toxicology

Title: Ketofol

Keywords: sedation, propofol, ketamine (PubMed Search)

Posted: 6/5/2008 by Ellen Lemkin, MD, PharmD (Emailed: 6/9/2008) (Updated: 4/13/2024)
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"Ketofol" (Ketamine plus propofol)

  • Given for conscious sedation, for all age groups
  • Takes advantage of properties of both agents
  • Ketamine generally produces hypertension, does NOT produce respiratory depression, has an emergence phenomena, and has analgesic properties
  • Propofol causes hypotension and respiratory depression, has NO analgesic properties, and may blunt both nausea and emergence phenomena seen with ketamine
  • Given as a 1:1 ratio of ketamine and propofol, both 10 mg/ml
  • Dose is usually 1-3 ml aliquots; median dose in a recent study was 0.75 mg/kg
  • Median recovery 15 minutes (5-45 minutes; 80% recovered in less than 20 minutes)

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Category: Toxicology

Title: Drug-induced long QT

Keywords: prolonged QT, arrhythmia, adverse effect, antiarrhythmics, antibiotics, antipsychotics (PubMed Search)

Posted: 5/1/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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  • Many meds cause a prolonged QT; this is due to a mutation of a gene that codes for the rapid component of the K+ rectifying current. This leads to problems with repolarization.
  • Drugs  causing prolonged QT with THERAPEUTIC doses include: antiarrhythmics (quinidine, procainamide, amiodarone, sotalol, and dofetilide)
  • Other agents that cause prolonged QT with ELEVATED serum concentrations include: antihistamines, some antibiotics and psychiatric meds (amitriptyline, cisapride, erythromycin, pimozide, thioridazine, SSRIs, trazodone, and moxifloxacin)
  • Use caution when combining medications from either, or both groups!

Other factors that are associated with prolonged QT include: bradycardia, female sex, genetics, and electrolyte abnormalities.

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Category: Toxicology


Keywords: antiepileptics, suicide, carbamezepine, felbamate, gabapentin, lamotrigine, levetiracetam, valproate, pregabalin (PubMed Search)

Posted: 4/3/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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  • On January 31st, the FDA released a warning about an increased risk of suicidality in patients recently started on antiepileptics
  • They analyzed data across 199 placebo controlled trials, looking at 11 agents in a total of 43,892 patients
  • Patients taking antiepileptics were found to have twice the suicide ideations and attempts as those on placebo.
  • Although the overall risk was very small (0.43% vs 0.22%), it is consistent across the board, and particularly evident in those with epilepsy.

Drugs in the analysis included:
Carbamazepine (Carbatrol, Equetro, Tegretol, Tegretol XR)
Felbamate (Felbatol)
Gabapentin (Neurontin)
Lamotrigine (Lamictal)
Levetiracetam (Keppra)
Oxcarbazepine (Trileptal)
Pregabalin (Lyrica)
Tiagabine (Gabitril)
Topiramate (Topamax)
Valproate (Depakote, Depakote ER, Depakene, Depacon)
Zonisamide (Zonegran)

Interestingly, other agents including varenicline (a partial nicotinic antagonist, for smoking cessation), levetiracetam (Keppra), zolpidem (Ambien), oseltamivir (Tamiflu), isotretinoin (Accutane), and other agents have been noted to have an increased rate of bizarre and aggressive behavior.  

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Category: Toxicology


Keywords: amiodarone, torsades, hypothyroidism, toxicity, adverse effects, medication induced (PubMed Search)

Posted: 3/6/2008 by Ellen Lemkin, MD, PharmD (Updated: 4/13/2024)
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 Did you know how many toxicities and adverse effects amiodarone has? Many are severe, and many VERY common.

1. CARDIAC: hypotension with rapid infusion, prolonged QT, torsades

2. NEUROLOGIC problems occur in 20-40%, including malaise, ataxia, and peripheral neuropathies

3. ENDOCRINE: hypothyroidism and hyperthyroidism

4. GI problems occur in 25%

5. OPHTHALMOLOGIC disturbances include optic neuropathy, papilledema, and photosensitivity

6. SKIN: blue grey pigmentation

7. PULMONARY: pulmonary fibrosis