Neonatal Drug Therapy Manual

Gentamicin

Disclaimer: Official controlled document is the CHEO and Ottawa Hospital online copy. It is the responsibility of user to ensure that any paper copy version is the same as the online version before use.

Alternate Name(s): 
Garamycin
Classification: 
Antibiotic (Aminoglycoside)
Original Date: 
March 1993
Revised Date: 
Sept 2022
Indications: 
  • Treatment of infections due to Gram (-) organisms (e.g E. coli, Klebsiella, Proteus, Enterobacter and Serratia)
Administration: 
  • IV intermittent infusion: over 30 minutes
Dosage: 
EXTENDED INTERVAL DOSING: preferred method

Gestational Age and Post-Natal

Age

 

Dose

Therapeutic Drug Levels1

Preterm

<30 weeks GA

0-14 days

5 mg/kg/dose

Q48h

 

 

 

 

Target for Extended-Interval trough concentrations:

  • <2mg/L for pre-third dose (pre-second if applicable)1

 

If renal dysfunction is present,  longer dosing intervals and/or lower doses may be required if the aminoglycoside is to be continued.2 A trough value of ≤1mg/L may be considered as the goal in these certain cases; consult clinical pharmacist. 

>14 days

5 mg/kg/dose

Q36h

Preterm

30-34 weeks

GA

0-10 days

5 mg/kg/dose 

Q36h

> 10 days

5 mg/kg/dose

Q24h

Preterm & Term

>35 weeks

 

0-7 days

4 mg/kg/dose

Q24h

>7 days

5 mg/kg/dose

Q24h

1 TDM may not be necessary if therapy is anticipated to stop at 36-48 hours. A trough level can be obtained prior to the anticipated second dose but may be postponed to pre-third dose if there is no concern for renal dysfunction. Trough levels are obtained 0-60 minutes prior to the next anticipated dose and are a safety measure.

2 This would include neonates with suspected, possible or confirmed hypoxic ischemic events, undergoing therapeutic cooling, fluid imbalance, possible or suspected renal thrombosis, congenital renal anomalies or any other conditions that may be associated with transient or prolonged renal dysfunction.

 

 

TRADITIONAL DOSING
Gestational Age and Post-Natal Age  Dose Therapeutic Drug Levels3
Preterm (< 36 weeks GA) 0-14 days < 28 weeks GA 3 mg/kg/dose Q24H

Traditional Dosing (Pre and Post levels obtained after 48 hours if renal function remains normal)

 

Pre (0 - 30 minutes before dose): 0.5 - 2 mg/L

                                        AND

Post (30 minutes after end of a 30 minutes infusion): 5 - 10 mg/L

 

If renal dysfunction is present, consult clinical pharmacist as longer dosing intervals and/or lower doses may be required if the aminoglycoside is to be continued2

 

29-36 weeks GA 3.5 mg/kg/dose Q24H
> 14 days  < 28 weeks corrected GA 3-3.5 mg/kg/dose Q18h
> 29 weeks corrected GA 3-3.5 mg/kg/dose Q12h 
Term (> 37 weeks GA) 0-7 days  37 weeks GA 3-3.5 mg/kg/dose Q18H
> 7 days 2.5 mg/kg/dose Q8h4

Traditional Dosing

Pre and Post levels obtained on Day 3.  For dosage adjustment and timing of levels in renal impairment, consult pharmacist

2 This would include neonates with suspected, possible or confirmed hypoxic ischemic events, fluid imbalance, possible or suspected renal thrombosis, congenital renal anomalies or any other conditions that may be associated with transient or prolonged renal dysfunction.

3TDM may not be necessary if therapy is anticipated to stop at 36-48 hours. Trough (pre) AND peak (post) levels are recommended for traditional dosing. 

4 Typically, we would start extended interval dosing here (see Extended Interval Dosing Chart above), which is the preferred method in normal renal function 

Side Effects: 
  • Hematologic: anemia, granulocytopenia, thrombocytopenia
  • Local: thrombophlebitis
  • Neuromuscular and skeletal: neuromuscular blockade
  • Otic: vestibular/auditory toxicity
  • Renal: nephrotoxicity, increase risk with concurrent use of nephrotoxic drugs (eg. furosemide, indomethacin)
Parameters to Monitor: 
  • Renal: serum creatinine, urea, urine output
  • Therapeutic drug levels: see tables

** When checking level, administer next dose as scheduled. Do not wait for levels to be reported unless otherwise advised

Reconstitution and Stability: 

CHEO:

  • Gentamicin 40 mg/mL (doses < 10 mg)
    • Take 1 mL (40 mg) and add to 39 mL D5W
    • Final concentration: 1 mg/mL
  • Gentamicin 40 mg/mL (doses > 10 mg)
    • Take 1 mL (40 mg) and add to 7 mL D5W or 0.9% NaCl
    • Final concentration: 5 mg/mL

TOH:

  • Gentamicin 40 mg/mL
  • Take 1 mL (40 mg) and add to 39 mL D5W
  • Final concentration: 1 mg/mL
Compatibility: 

- Solutions Compatible: D5W, D10W, 0.9% NaCl, dextrose-saline combinations

- Y-site Compatible:  dexmedetomidine, famotidine, fentanyl, fluconazole, KCl, heparin (low concentrations of 0.5 to 1 unit/mL that are used to maintain IV line patency), insulin, meropenem, midazolam, morphine, penicillin G, ranitidine, TPN (amino acids- dextrose)

Incompatible: acyclovir, ampicillin, azithromycin, cloxacillin,  furosemide, heparin (concentrations greater than 1 unit/mL), indomethacin, pantoprazole, piperacillin/tazobactam, SMOF

Notes: 
  • Extended interval dosing is being introduced to help optimize efficacy and minimize aminoglycoside toxicity in this patient population

  • A trough level can be obtained prior to the anticipated second dose but may be postponed to pre-third dose if there is no concern for renal dysfunction and if it is anticipated that the duration will be > 48 hours. 
  • Peak concentrations 6-12 mg/L are generally obtained to see if targets for efficacy are being attained or for pharmacokinetic modeling purposes.
References: 

- Taketomo CK, Hodding JH, Kraus DM. Pediatric & Neonatal Dosage Handbook 22nd Editions. Hudson: Lexi-Comp Inc.; 2015

- American Society of Health-System Pharmacists (ASHP). Handbook on Injectable Drugs. 19th Edition. Bethesda: ASHP 2017

- Low YS, Tan SL, Wan A. Extended-Interval Gentamicin Dosing in Achieving Therapeutic Concentrations in Malaysian Neonates. J Pediatr Pharmacol Ther. 2015. Mar-Apr, 20 (2): 119-127.

- Bergenwall M, Walker SAN, Elligsen M, Iaboni DC, Findlater C, Seto W, Ng E. Optimizing gentamicin conventional and extended interval dosing in neonates using Monte Carlo simulation - a retrospective study. BMC Pediatr. 2019 Sep 6;19(1):318. 

- König K, Lim A, Miller A, Saker S, Guy KJ, Barfield CP. Gentamicin trough levels using a simplified extended-interval dosing regimen in preterm and term newborns. Eur J Pediatr. 2015 May;174(5):669-73. doi: 10.1007/s00431-014-2450-z. 

- van Maarseveen EM, Sprij A, Touw DJ. Extended-Interval Dosing of Gentamicin Aiming for a Drug-Free Period in Neonates: A Prospective Cohort Study. Ther Drug Monit. 2016 Jun;38(3):402-6. 

- Red Book (Committee on Infectious Diseases, American Academy of Pediatrics); David W. Kimberlin, MD, FAAP, Elizabeth D. Barnett, MD, FAAP, Ruth Lynfield, MD, FAAP, Mark H. Sawyer, MD, FAAP. American Academy of Pediatrics. Publication date: January 2021.

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