Aim In April 2017 the Trust updated the Neonatal Infection Guideline due to increasing resistance to gentamicin. Subsequently, the first line aminoglycoside to treat early onset sepsis (EOS) on neonatal units (NNU) for patients ≤32 weeks gestation changed from gentamicin to amikacin.
Updated guidance recommends prescribing amikacin 15 mg/kg 24 hourly, aiming for trough levels<5 mg/L; however anecdotal reports suggest this results in frequently high trough levels at 24 hours.
Adherence to current guidelines was audited, to gain insight into the most appropriate dosing interval to use, particularly in extremely low birth weight (<1 kg) and extremely premature neonates (<28 weeks gestation at birth).
100% of patients prescribed amikacin for EOS adhere to criteria in Neonatal Infection Guideline
100% of patients prescribed amikacin dose of 15 mg/kg
100% of patients prescribed amikacin have a blood level taken at 24 hours (prior to giving second dose)
100% of patients receive further doses of amikacin only when blood levels are <5 mg/L, or under the advice of a pharmacist
Method Audit standards were derived from hospital policy. All eligible neonates receiving amikacin were included. Neonates on postnatal wards were excluded; they should receive gentamicin for treatment of EOS.
Prospective data collection was completed across both NNUs at the Trust, which included all neonates that received doses of amikacin from 1st April to 1st August 2017. Data were collected from drug charts and medical records. Data were also collected to account for factors that could contribute to or highlight that the patient suffered from poor renal output; degree of prematurity (gestational age), urine output, urea and electrolytes, any inotropic support, or a significant patent ductus arteriosus. Data were entered onto an Excel spread sheet and were summarised descriptively. The audit was approved locally.
Results A total of 50 neonates received amikacin. 100% adhered to criteria in Neonatal Infection Guideline and 100% prescribed doses of 15 mg/kg. 12 patients (24%) did not have an amikacin level taken at 24 hours, of which 5 (42%) had stopped antibiotics and 7 (58%) had levels taken between 27–36 hours. Of the remaining 38 patients, only 6 (16%) had levels<5 mg/L at 24 hours. Nine (24%) patients then stopped antibiotics at 36 hours. 23 patients had levels taken at 36 hours, of which 17 (74%) could be classed as ‘in range’ at ≤5 mg/L. Two patients received doses despite levels of >5 mg/L. Final results are yet to be fully analysed, however it appears as though there is no direct correlation between gestational age, severity of illness and amikacin level results.
Conclusion Findings suggest it is difficult to pre-determine how a patient will excrete amikacin, even when taking into account gestational age and birth weight; which would support the literature.¹ However, the majority of levels were high at 24 hours and within range by 36 hours, so change in practice from 24 hourly to 36 hourly dosing is recommended. Following implementation of the recommendations, further audit is necessary in one year.
Allegaert K, Anderson BJ, Cossey V, et al. Limited predictability of amikacin clearance in extreme premature neonates at birth. British Journal of Clinical Pharmacology2005;61:39–48.
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