UMEM Educational Pearls - Pharmacology & Therapeutics

Category: Pharmacology & Therapeutics

Title: IV acetaminophen

Keywords: acetaminophen,pain,narcotic,Ofirmev,intravenous (PubMed Search)

Posted: 5/5/2011 by Ellen Lemkin, MD, PharmD
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IV acetaminophen has been approved for use since November 2010

It is indicated for the:

  • Treatment of mild to moderate pain
  • Combination therapy with opioids for treatment of moderate to severe pain
  • Fever reduction

The results of studies demonstrating opoid sparing effects have been mixed; some studies have not demonstrated either a reduction in opioid dose or opioid side effects.

The dose is the same for acetaminophen administered by other routes.

It must be administered over 15 minutes, and onset of activity is 15 minutes. Peak effect occurs at one hour.

The MAJOR drawback is the cost, which is $13 dollars per vial. This is compared to oral acetaminophen and ibuprofen, which are pennies.

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Category: Pharmacology & Therapeutics

Title: Enoxaparin Dosing in Obese Patients

Keywords: enoxaparin, VTE, obese, low molecular weight heparin (PubMed Search)

Posted: 4/1/2011 by Bryan Hayes, PharmD (Emailed: 4/2/2011) (Updated: 4/2/2011)
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For patients with normal renal function, enoxaparin dosing for treatment of VTE is 1 mg/kg subcut every 12 hours OR 1.5 mg/kg subcut every 24 hours.

Studies have evaluated dosing for patients weighing up to 190 kg and found the 1 mg/kg q 12 hours dose to be safe and effective.  It can even be used for patients heavier than 190 kg, but anti-Xa monitoring is recommended.

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Category: Pharmacology & Therapeutics

Title: Antimicrobial Treatment Algorithm for PCP Pneumonia in the ED

Keywords: PCP, clindamycin, primaquine, pentamidine, dapsone, atovaquone (PubMed Search)

Posted: 2/22/2011 by Bryan Hayes, PharmD (Emailed: 3/5/2011) (Updated: 3/5/2011)
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Sulfamethoxazole (SMX)/trimethoprim (TMP) is the treatment of choice for PCP pneumonia. The IV formulation has been unavailable for almost a year due to shortage. It is contraindicated in patients with sulfa allergy. Here are the alternatives with adverse effects. You'll quickly see why pentamidine should generally be reserved for those with sulfa allergy and G6PD deficiency.

Mild-to-moderate disease:

  1. Primaquine 15-30 mg PO PLUS Clindamycin 600 mg IV or 300-450 mg PO
  2. Dapsone 100 mg PO PLUS TMP 5 mg/kg PO
  3. Atovaquone suspension 750 mg PO

Moderate-to-severe disease:

  1. Primaquine 15-30 mg PO PLUS Clindamycin 600 mg IV or 300-450 mg PO
  2. Pentamidine 4 mg/kg IV

Adverse Effects:

  • Primaquine: Rash, fever, methemoglobinemia, hemolytic anemia (check for G6PD deficiency)
  • Clindamycin: Rash, diarrhea, Clostridium difficile colitis, abdominal pain
  • Dapsone: Rash, fever, gastrointestinal upset, methemoglobinemia, hemolytic anemia (check for G6PD deficiency)
  • TMP: Rash, gastrointestinal distress, transaminase elevation, neutropenia
  • Atovaquone: Rash, fever, transaminase elevation
  • Pentamidine: Nephrotoxicity, hyperkalemia, hypoglycemia, hypotension, pancreatitis, dysrhythmias, transaminase elevation

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Category: Pharmacology & Therapeutics

Title: Immediate Hypersensitivity Reactions (IHR) to Radio Contrast Media (RCM)

Keywords: iohexol, iodixanol, radio contrast media, immediate hypersensitivity reactions (PubMed Search)

Posted: 2/5/2011 by Bryan Hayes, PharmD
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Many patients report an allergy to iodinated RCM, sometimes adding to the complexity of diagnostic decision making.  Here are a few pearls to help:

  • Seafood or shellfish allergy is NOT a risk factor for IHR to RCM
  • Iodine and iodide are small molecules that do NOT cause anaphylactic or anaphylactoid reactions
  • Life-threatening reactions occur in only 0.004 to 0.04 percent of nonionic low osmolality RCM infusions
    • Our radiology department uses primarily iohexol (Omnipaque) for IV contrast with a low osmolality of 844
    • Iodixanol (Visipaque) is the iso-osmotic alternative with an osmolality of 290

Bottom line: Despite the lack of cross reactivity with shellfish/iodine allergies AND the very low risk associated with today’s low osmolality agents, premedication is still indicated in patient’s with a history of IHR to RCM.

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