Tag Archives: #PO

5 random facts about antimicrobials

Who doesn’t love to pick up random bits of information while they’re in line for their coffee or their morning signout? Here are 5 helpful pieces of information on antimicrobials to start off your day!

1.Cefepime vs. Piperacillin-tazobactam
Cefepime – cephalosporin
– DOES NOT cover gut anaerobes
– DOES NOT cover Enterococcus spp.
Piperacillin-tazobactam – penicillin derivative
– DOES cover gut anaerobes
– DOES cover penicillin-sensitive Enterococcus spp.

Antibiotic Cefepime Piperacillin/tazobactam
Class Cephalosporin Penicillin derivative
Gut anaerobic coverage? No Yes
Enterococcus coverage? No Yes (if susceptible)

 

2. Cephalosporins in general DO NOT cover Enterococcus spp.

3. Ertapenem vs. meropenem vs. imipenem vs. doripenem
Ertapenem – DOES NOT cover Pseudomonas spp.
Meropenem/Imipenem/Doripenem – DO cover Pseudomonas spp.
*None of the carbapenems cover MRSA

4. Ineffective antimicrobials
Daptomycin – inactivated by the surfactant in the lungs
– DO NOT use daptomycin to treat lung infections
*Remember: Linezolid, Lung (you can use Linezolid for lung infections)

Echinocandins (ex. micafungin, caspofungin, anidulafungin) – do not reach therapeutic levels in the urinary tract
– DO NOT use echinocandins to treat pyelonephritis or urinary tract infections

Tigecycline – accumulates in the tissues and has low concentration levels in the bloodstream
– DO NOT use tigecycline to treat bloodstream infections

5. Bone marrow toxicity due to linezolid increases after 2 weeks of exposure
– Avoid using linezolid for more than two weeks at a time when possible

 

Do you have any random facts of ID knowledge? Let me know in the comments section below!

 

References:

1. Mandell, Douglas, and Bennett. Principles and practice of infectious diseases. Philadelphia, PA: Churchill Livingstone/Elsevier, c2010. 7th edition.
2. Zhanel, G.G. et al. 2007. Comparative review of the carbapenems. Drugs. 67(7):1027-1052.
3. Gerson, S.L. et al. 2002. Hematologic effects of linezolid: summary of clinical experience. Antimicrobial Agents and Chemotherapy. 46(8): 2723-2726.
4. Malani, A.N. et al. 2014. Candida urinary tract infections: treatment options. 5(2): 277-284.
5. Jeu, L. et al. 2004. Daptomycin: a cyclic lipopeptide antimicrobial agent. Clinical Therapeutics. 26(11): 1728-1757.

Peer-reviewed by Jeff Pearson, PGY-2 pharmacy resident

Oral vs. IV antimicrobials

What’s the difference between oral (PO) and IV medications? When do you use PO vs. IV antimicrobials? When are they interchangeable? These are the questions we’ll address in this post.

info intravenously picture
by Dalya Ferguson, MD

Bioavailability is an important concept to understand when considering IV to PO interchange.

Bioavailability = the measure of the amount of an orally administered medication that reaches the bloodstream.

Antimicrobials with >90% bioavailability are the antimicrobials we can target for
IV to PO interchange.

Antimicrobials where bioavailability >90%:
(therefore, can be switched to PO)

  • Metronidazole
  • Fluoroquinolones (levofloxacin, moxifloxacin, *ciprofloxacin has ~70% bioavailability but still has enough to achieve adequate levels in the bloodstream)
  • Trimethoprim-Sulfamethoxazole
  • Tetracyclines (doxycycline, minocycline)
  • Linezolid
  • Rifampin
  • Fluconazole/Voriconazole
  • Clindamycin
  • Azithromycin (only ~40% bioavailable, but the concentration achieved by
    oral ingestion is just as effective as IV for treatment)

 

IV medication = medication given intravenously
– medication takes effect immediately after the infusion
– administers a bolus of the medication quickly (within 5 minutes)
– requires an IV line
– bypass first pass metabolism in the liver

PO medication = medication administered per oral route
– medication takes effect in ~30 minutes to 6 hours
– requires ability to swallow, absorb the medication, and also undergoes
first pass metabolism prior to reaching the circulatory system

Why is PO preferable to IV?

  • Cheaper3
  • Does not require IV access
  • Easier and faster to administer
  • No IV complications (i.e. phlebitis, thrombosis, bloodstream infection)
  • Avoidance of a long-term catheter such as a PICC line
  • Less unnecessary fluid administration

 

When to consider IV antimicrobials?

  • when patient is unable to take PO or unable to absorb the medication
  • when you want immediate effect of the medication
  • when the spectrum of activity desired is only available with IV antibiotics
  • when no PO option is available to treat the pathogen
  • when PO medications will not achieve high enough concentrations or penetrations to the location of the infection
    • Critically ill patients; sepsis/bacteremia
    • Endocarditis
    • CNS/ocular infection
    • Osteomyelitis/Septic arthritis (*a study is currently under way, looking at whether certain oral antibiotics are non-inferior to IV antibiotics in
      bone infections7)
      *You may occasionally see these syndromes treated with oral antibiotics, because each case is different. But in general, consider these syndromes as ones where IV antibiotics are preferred, especially as initial therapy.

 

TAKE HOME POINTS:

  • IV antimicrobials are NOT “stronger” or “better” than oral antimicrobials
    – it depends on each individual medication
  • PO antibiotics should be used unless there is a reason to use IV antibiotics (and not the other way around)
  • When PO and IV versions of an antimicrobial are similar, make every concerted effort to make sure your patients are not on IV medications unnecessarily

 

Questions? Comments? Suggestions for future posts? Leave a comment below.

 

 

References:

  1. Kwong, L.H et al. (2015). An unsupported preference for intravenous antibiotics. PLoS medicine, 12(5): e1001825. DOI: 10.1371/journal.pmed.1001825
  2. MacGregor, R.R. et al. (1997). Oral administration of antibiotics: a rational alternative to the parenteral route. 24: 457-467. PMID: 9114201
  3. Chan, R. et al. (1995). Oral versus intravenous antibiotics for community acquired lower respiratory tract infection in a general hospital: open, randomized, controlled trial. BMJ. 310: 1360-1362. PMID: 7787537
  4. Baddour et al. (2016). Infective Endocarditis in Adults: Diagnosis, Antimicrobial Therapy, and Management of Complications. Circulation. 132: 1435-1486.
    DOI: 10.1161/CIR.0000000000000296.
  5. Tunkel, A.R. et al. (2004). Practice Guidelines for the Management of Bacterial Meningitis. CID. 39: 1267-1284. DOI: 10.1086/425368
  6. World Health Organization, Occupational Health. (date published unknown). Comparison of pharmacokinetics and efficacy of oral and injectable medicine [Powerpoint slides]. Retrieved from http://www.who.int/occupational_health/activities/5injvsora.pdf
  7. Li, H.K et al. (2015). Oral versus intravenous antibiotic treatment for bone and joint infections (OVIVA): study protocol for a randomized controlled trial. BMC Trials. 16:583. DOI: https://doi.org/10.1186/s13063-015-1098-y
  8. Wisplinghoff, H. et al. (2004). Nosocomial bloodstream infections in US hospitals: analysis of 24,179 cases from a prospective nationwide surveillance study. Clin Infect Dis. 39(3): 309-317. DOI: 0.1086/421946

 

Peer-reviewed by Jeff Pearson, 2nd year PharmD resident