UMEM Educational Pearls - Pharmacology & Therapeutics

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)
Click here to contact Bryan Hayes, PharmD

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:

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

Moderate-to-severe disease:

Primaquine 15-30 mg PO PLUS Clindamycin 600 mg IV or 300-450 mg PO
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

Show References

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
Click here to contact Bryan Hayes, PharmD

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.