PharmPK Discussion - Gentamicin in endocarditis

• On 28 May 1996 at 12:30:27, Randy Trinkle (rtrinkle.at.pris.bc.ca) sent the message
  

  
  (1) What is the organism?
  
  (2) What are the other antibiotics being used?
  
  (3) Is ampicillin (or another beta-lactam) being used, and is it being
  given by continuous infusion?
  
  Randy Trinkle, BScPharm, BA
  Dept. of Pharmacy
  Dawson Creek & District Hospital
  Dawson Creek, BC
  rtrinkle.-a-.pris.bc.ca
  
  

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• On 28 May 1996 at 12:30:33, "Michael Burton" (michael.burton.-at-.DISPATCHER.NET.uokhsc.edu) sent the message
  

  
  Based on my past experience, high peaks are important to ensure penetration
  of gentamicin into the vegetation.  One previous patient that I was involved
  in the treatment received tobramycin at a dose to produce peaks of 15 mg/L
  and troughs of <1 mg/L. for a Pseudomonas aeruginosa endocarditis.  The
  patient was successfully treated, although 2 courses of therapy were required
  without nephrotoxicity.  With the elevated trough levels, it is unlikely that
  the patient will be able to complete the required 6-8 weeks of therapy with
  gentamicin due to nephrotoxicity.  Depending on the age of the patient,
  nephrotoxicity is likely to be seen starting at 5 days into the therapy.  The
  question is one of is it more important to complete the duration of therapy
  without nephrotoxicity or have a short course due to high troughs with
  resultant nephrotoxicity with limited penetration into the vegetation.  Since
  there is no blood flow to the valves except the surrounding blood in the
  heart, high peaks to facilitate diffusion into the vegetation seem more
  important to me.
  
  

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• On 29 May 1996 at 10:29:17, Steve Ebert (sebert.aaa.facstaff.wisc.edu) sent the message
  

  
  As Mike Burton has noted, the type of bacterium causing the endocarditis may
  influence the importance of serum concentration monitoring.  For Pseudomonas
  endocarditis, I agree that high concentrations (tobramycin peaks of 10-14
  mcg/mL) are best, with troughs <1 mcg/mL.  On the other hand, for
  staphylococcal, alpha-streptococcal, or enterococcal endocarditis, lower
  peaks (5 mcg/mL or less) with troughs <1 are probably sufficient.  SCE
  
  

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• On 31 May 1996 at 10:59:38, S.McLean.aaa.pharm.utas.edu.au (Stuart McLean) sent the message
  

  
  Thanks to those who replied to this question.
  
  In response to follow-up questions from Randy Trinkle:
  
  >(1) What is the organism?
  
  UNKNOWN UNTIL VALVE IS REMOVED AND CULTURED.
  
  >(2) What are the other antibiotics being used?
  
  VANCOMYCIN, INITIALLY I.V. 500 MG 12 HOURLY, NOW 1 G DAILY.
  
  >(3) Is ampicillin (or another beta-lactam) being used, and is it being
  >given by continuous infusion?
  
  NO.
  __________________________________________________
  Stuart McLean, MPharm, PhD
  School of Pharmacy
  University of Tasmania                International callers:
  GPO Box 252C, Hobart 7001
  Australia                             Email 
  WWW server: http://www.healthsci.utas.edu.au/pharmacy/pharm.html
  
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