GENTAMICIN SULPHATE

Gentamicin DBL

Reviewed by Clinical Guidelines Committee
April 2012
 
Administration Newborn Drug Protocol Index Newborn Services Home Page

 

Dose and Administration

  1. Intravenous infusion over 20 to 30 minutes, or IM injection.
  2. There is no loading dose to be administered.
  3. Obtain trough level and serum creatinine level prior to the second dose and withhold the dose while result is awaited (unless gentamicin is due to be stopped at 48 hours). See Special Considerations below.
Postmenstrual Age
(weeks)
Postnatal Age
(days)
Dose
(mg/kg/dose)
Interval
(hours)
≤29
(or significant asphyxia)
0 to 7 5 mg/kg 48 hourly
8 - 30 5 mg/kg 36 hourly
> 30 5 mg/kg 24 hourly
30 to 36 0 to 7 5 mg/kg 36 hourly
> 7 4 mg/kg 24 hourly
≥37 Any 4 mg/kg 24 hourly

Indications

  1. Empirical therapy for those VLBW infants with risk factors for perinatal sepsis in the first week of life.
  2. Proven neonatal sepsis (pneumonia, septicaemia, urinary tract infections, CNS infections, skin, bone and soft tissue infection), with bacteria known to be sensitive (note: Staph epidermidis is resistant).

Contraindications and Precautions

  1. Known hypersensitivity to gentamicin/other aminoglycosides.
  2. Use in treatment of minor infections.
  3. Extreme caution in neonates with renal dysfunction.
  4. Caution in concurrent therapy with cephalosporins, potent diuretics such as furosemide, and neuromuscular blocking agents.
  5. Concurrent administration with other ototoxic and/or nephrotoxic drugs.

Clinical Pharmacology

Bacteriocidal aminoglycoside antibiotic which inhibits bacterial protein synthesis. Active against a wide variety of pathogenic gram negative and gram positive bacteria, including Escherichia coli, Enterbacter spp, Pseudomonas aeruginosa, Proteus spp, Serratia spp, Staphylococcus spp (including penicillin and methicillin resistant strains).

Poorly absorbed by the oral route, variable absorption from intramuscular injection sites. Diffuses through the plasma and interstitial fluid volumes. Does not penetrate the CSF to any significant extent. Low binding (25-30%) to human plasma protein. Thought to be excreted unchanged, eliminated mainly by the kidney. Renal clearance of gentamicin appears to be slightly less than that of endogenous creatinine. Reduction in serum concentrations can be achieved by peritoneal dialysis or haemodialysis.

Possible Adverse Effects

  1. Nephrotoxicity (transient and reversible renal tubular dysfunction).
  2. Ototoxicity (vestibular injury irreversible. More likely to occur if Gentamicin used concomitantly with other nephrotoxic medications).
  3. Neurotoxicity (neuromuscular weakness and respiratory failure potentiated with concomitant treatment with neuromuscular blocking agents or in patients with hypermagnesaemia).
  4. Venous irritation, soft tissue injury at IV injection site.
  5. Pain, soft tissue injury at IM injection site.
  6. Gastrointestinal (elevated liver enzymes).
  7. Blood dyscrasias (rare).
  8. Hypersensitivity (rash, urticaria, fever, laryngeal oedema).

Special Considerations

  1. May be used in combination with other antibiotics if infused separately.
  2. Adjust dose and/or dose interval in infants with suspected/proven renal impairment, or reduced renal clearance due to extreme immaturity.
  3. Monitoring:
  4. Ototoxicity risk is difficult to predict and can occur despite target serum trough levels especially in infants with other risk factors. All infants treated with Gentamicin for longer than 48 hours should have audiology testing.

 

References

1 Neonatal Formulary BMJ Books 6th Edition 2011 p 120
2 Young TE, Magnum B. Neofax 16th Edition 2003 A Manual of Drugs Used in Neonatal Care.
3 Begg EJ, Barclay ML, Kirkpatrick CMJ. The therapeutic monitoring of antimicrobial agents. Br J Clin Pharmacol. 2001:52; 35S-43S
4 Hoff D S, Wilcox RA, Tollefson LM, Lipnik PG, Commers AR, Liu M. Pharmacokinetic Outcomes of a Simplified, Weight-Based, Extended-Interval Gentamicin Dosing Protocol in Critically Ill Neonates. Pharmacotherapy. 2009.29: 1; 1297-1305
5 Best EJ, Gazarian M, Cohn R, Wilkinson M, Palasanthiran P. One-daily Gentamicin in infants and children. A prospective cohort study evaluating safety and the role of therapeutic drug monitoring in minimizing toxicity.  Pediatr Infect Dis J. 2011. 30:10;827-32