Description and indication for use

Gentamicin is an aminoglycoside antibiotic active against a wide range of gram –ve bacteria. It is bactericidal and acts by inhibiting protein synthesis in susceptible bacteria. Its use requires therapeutic drug monitoring to prevent nephrotoxicity. When used in combination with a penicillin antibiotic, gentamicin has a synergistic effect.

Dose

Dosing interval varies with weight and postnatal age. ALWAYS check the dose and frequency of the previously administered dose. Consider using an alternative antibiotic in patients with renal failure. 

IV AND IM:

5 mg/kg/dose.^1,6,7

Interval^1,7:

Method of Administration

Ampoule = 80 mg/2 mL = 40 mg/mL.

IV:

Withdraw 2 mL of 40 mg/mL solution and dilute with 6 mL of sodium chloride 0.9% to make a solution of 10 mg/mL.

Babies < 1200 g: Withdraw required dose from the 10 mg/mL solution and add to 0.5 mL of sodium chloride 0.9% in a 3 mL syringe.

Babies ≥ 1200 g: Withdraw required dose from the 10 mg/mL solution and give undiluted.

Infuse over 30 minutes where possible¹ or give undiluted over at least 3 minutes.

IM:

Withdraw required dose and administer undiluted.³

Not for Subcutaneous use.³ 

Compatibility Information

Administer alone or contact pharmacy for drugs not appearing in the table below:

Aminoglycoside antibiotics (Amikacin, Gentamicin, Tobramycin) are inactivated by Penicillins and Cephalosporins – separate doses by one hour or flush the line well with NaCl 0.9% before and after giving doses.²

Adverse Effects

Ototoxicity.

Nephrotoxicity.

Rash.

Contraindications and Precautions

CAUTION in patients with renal impairment; monitor levels as below and adjust the dosing interval as necessary.

Contraindicated in myasthenia gravis.

Concurrent treatment with other nephrotoxic drugs (e.g. Vancomycin, Amphotericin, Ibuprofen).

Concurrent treatment with other ototoxic drugs (e.g. Frusemide).

Gentamicin can prolong the action of Pancuronium.  

Medical/Nursing responsibilities

Monitor urine output, creatinine and urea.

If a patient has received a dose of Gentamicin prior to admission to NNU, record the dose given and time of administration on the medication chart.

Therapeutic Drug Monitoring:

Trough level to be taken immediately prior to the 3^rd dose* and if the level is <2 mg/L^1,6, repeat a trough level every 3 days.**

     *  immediately prior to the 2^nd dose and HOLD the dose until the result is available in patients with renal impairment (elevated serum creatinine and/or poor urine output) or if a dose/interval has been adjusted due to an elevated Gentamicin level.

     **  check doses more frequently in patients with renal impairment to prevent accumulation.

There is no need to withhold the dose until the level is available (“level and hold”) in patients with normal renal function unless they have had high gentamicin levels previously.

References:

1.   RWH Neonatal Pharmacopoeia 2^nd ed. 2005.
2.   RCH Paediatric Injectable Guidelines 4^th ed. 2011.
3.   Australian Injectables Handbook, SHPA, 5th ed. 2011.
4.   Lawrence Trissel, Handbook on Injectable Drugs, 17th ed. 2013.
5.   Thomson Young et al.  Neofax 22nd ed. 2009.
6.   British National Formulary for Children 2013 – 2014.
7.   Taketomo, C.K., Hodding, J.H. and Kraus, D.M. (2011) Pediatric and Neonatal Dosage Handbook, 18^th edition, Lexi-Comp, Ohio.