Antibiotics in Neonates

Brenda L. Tesini

, MD, University of Rochester School of Medicine and Dentistry

Last full review/revision Jul 2020| Content last modified Jul 2020

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Vancomycin Dosage for Neonates

In neonates, the extracellular fluid (ECF) constitutes up to 45% of total body weight, requiring relatively larger doses of certain antibiotics (eg, aminoglycosides) compared with adults. Lower serum albumin concentrations in premature infants may reduce antibiotic protein binding. Drugs that displace bilirubin from albumin (eg, sulfonamides, ceftriaxone) increase the risk of kernicterus.

Absence or deficiency of certain enzymes in neonates may prolong the half-life of certain antibiotics (eg, chloramphenicol) and increase the risk of toxicity. Changes in glomerular filtration rate and renal tubular secretion during the first month of life necessitate dosing changes for renally excreted drugs (eg, penicillins, aminoglycosides, vancomycin).

Recommended Dosages of Selected Parenteral Antibiotics for Neonates

			Intervals of Administration
Antibiotic	Route of Administration	Individual Dose	Body Weight ≤ 2000 g		Body Weight > 2000 g		Comments
			Age		Age
			≤ 7 days	8–28 days	≤ 7 days	8–28 days
Amikacin (see Table: Recommended Dosages of Select Aminoglycosides for Neonates)	—	—	—	—	—	—	—
Amphotericin B deoxycholate	IV	1 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	After dilution in 5% or 10% D/W (saline solution should not be used), infusion of a test dose of 0.1 mg/kg (maximum 1 mg) over 1 hour to assess patient’s febrile and hemodynamic response;* if no serious adverse effects are observed, infusion of a therapeutic dose (usually 0.25–1.5 mg/kg over 2–6 hours), which may be given the same day as the test dose After the patient improves, may give the dose every other day until therapy is complete Monitoring of potassium levels and hematologic and renal functions required
Amphotericin B lipid complex	IV	5 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	—
Amphotericin B liposomal	IV	5 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	—
Ampicillin	IV, IM	50–75 mg/kg	50 mg/kg every 12 hours	75 mg/kg every 12 hours	50 mg/kg every 8 hours	50 mg/kg every 8 hours	IV as 15- to 30-minute infusion (≤ 10 mg/kg/minute)
For GBS meningitis	IV	75–100 mg/kg	100 mg/kg every 8 hours	75 mg/kg every 6 hours	100 mg/kg every 8 hours	75 mg/kg every 6 hours
Azithromycin	IV	10 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	For chlamydial pneumonia, 20 mg/kg every 24 hours
Aztreonam	IV, IM	30 mg/kg	Every 12 hours	Every 8 hours†	Every 8 hours	Every 6 hours	Limited data For gram-negative bacilli only
Cefazolin‡	IV, IM	25 mg/kg	Every 12 hours	Every 8 hours†	Every 12 hours	Every 8 hours	Limited data No primary indication; not used as initial therapy for sepsis or meningitis
Cefepime	IV, IM	30–50 mg/kg	30 mg/kg every 12 hours	30 mg/kg every 12 hours	50 mg/kg every 12 hours	50 mg/kg every 12 hours	May be used for Pseudomonas aeruginosa infections (consider using 50 mg/kg every 8 hours for P. aeruginosa and other serious gram-negative pathogens) Sometimes used for meningitis, although usually as a 2nd-line drug and not always recommended
Cefotaxime	IV, IM	50 mg/kg	Every 12 hours	Every 8 hours†	Every 12 hours	Every 8 hours	Often a first-line therapy for neonatal meningitis
Cefoxitin	IV, IM	33–35 mg/kg	35 mg/kg every 12 hours	33 mg/kg every 8 hours†	33 mg/kg every 8 hours	33 mg/kg every 8 hours	—
Ceftazidime	IV, IM	50 mg/kg	Every 12 hours	Every 8 hours†	Every 12 hours	Every 8 hours	Penetrates well into inflamed meninges 70–90% of drug excreted unchanged in urine
Ceftriaxone	IV, IM	50 mg/kg	—	—	Every 24 hours	Every 24 hours	Limited data May cause biliary pseudolithiasis and, in jaundiced premature infants, may increase risk of bilirubin encephalopathy via displacement of bilirubin from albumin Contraindicated in neonates receiving or expected to receive infusions of calcium-containing solutions 2nd-line drug for meningitis, after the first week of life (40–50 mg/kg every 12 hours or 80–100 mg/kg every 24 hours)
Cefuroxime	IV, IM	50 mg/kg	Every 12 hours	Every 8 hours†	Every 12 hours	Every 8 hours	—
Chloramphenicol	IV, IM	25 mg/kg	Every 24 hours	Every 12 hours†	Every 24 hours	Every 12 hours	Doses adjusted by monitoring serum drug levels and hematologic parameters For meningitis, desired peak serum levels = 15–25 mcg/mL (46.4–77.4 micromol/L) and trough levels = 5–15 mcg/mL (15.5–46.4 micromol/L) For other infections, dose adjusted to attain a peak level of 10–20 mcg/mL (31–62 micromol/L) and a trough level of 5–10 mcg/mL (15.5–31 micromol/L) Large variability in serum levels and serum half life, especially in preterm neonates
Clindamycin	IV, IM	5–9 mg/kg	5 mg/kg every 8 hours	5 mg/kg every 8 hours	7 mg/kg every 8 hours	9 mg/kg every 8 hours	For anaerobes and gram-positive cocci (not enterococci)
Daptomycin	IV	6 mg/kg	Every 12 hours	Every 12 hours	Every 12 hours	Every 12 hours	Neurotoxicity potential; use with caution if no other options
Fluconazole							—
For treatment	IV	12 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	Loading dose of 25 mg/kg followed 24 hours later by maintenance dose listed
For prophylaxis	IV	6 mg/kg	Twice weekly	Twice weekly	Twice weekly	Twice weekly
Gentamicin, tobramycin (see Table: Recommended Dosages of Select Aminoglycosides for Neonates)	—	—	—	—	—	—	—
Linezolid	IV	10 mg/kg	Every 12 hours	Every 8 hours	Every 8 hours	Every 8 hours	—
Meropenem							—
For meningitis	IV	40 mg/kg	Every 12 hours	Every 8 hours§	Every 8 hours	Every 8 hours
For sepsis, intra-abdominal infection§	IV	20–30 mg/kg	20 mg/kg every 12 hours	20 mg/kg every 8 hours§	20 mg/kg every 8 hours	30 mg/kg every 8 hours
Metronidazole	IV	7.5–10 mg/kg	7.5 mg/kg every 12 hours	7.5 mg/kg every 12 hours	7.5 mg/kg every 8 hours	10 mg/kg every 8 hours	Limited data Loading dose of 15 mg/kg
Nafcillin, oxacillin							—
For meningitis	IV, IM	50 mg/kg	Every 12 hours	Every 8 hours†	Every 8 hours	Every 6 hours	Monitoring of CBC and liver tests required Excretion may be decreased due to renal and hepatic immaturity, leading to possible accumulation in serum, which may have adverse effects
For other diseases	IV, IM	25 mg/kg	Every 12 hours	Every 8 hours†	Every 8 hours	Every 6 hours
Oxacillin (see Nafcillin, oxacillin)	—	—	—	—	—	—	—
Penicillin G, benzathine	IM	50,000 units/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	—
Penicillin G, crystalline (aqueous)							—
For congenital syphilis, other indications	IV	50,000 units/kg	Every 12 hours	Every 8 hours	Every 12 hours	Every 8 hours
For GBS meningitis	IV	100,000 units/kg	Every 6 hours	Every 6 hours	Every 6 hours	Every 6 hours
Penicillin G, procaine	IM	50,000 units/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	CAUTION: Sterile abscess and procaine toxicity
Piperacillin/tazobactam	IV (dose based on piperacillin component)	80–100 mg/kg	100 mg/kg every 8 hours	80 mg/kg every 6 hours║	80 mg/kg every 6 hours	80 mg/kg every 6 hours	—
Rifampin	IV	10 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours
Tobramycin (see Table: Recommended Dosages of Select Aminoglycosides for Neonates)	—	—	—	—	—	—	—
Vancomycin (see Table: Vancomycin Dosage for Neonates)	—	—	—	—	—	—	Dosing based on gestational age and serum creatinine (see Table: Vancomycin Dosage for Neonates)
* The need to administer a test dose of amphotericin B is controversial.
† Use the dose for age ≤ 7 days until 14 days of age if the birth weight is < 1000 g.
‡ Cefazolin does not cross the blood-brain barrier.
§ Adjust dosage after 14 days of age instead of after 7 days of age.
║ When postmenstrual age reaches > 30 weeks.
CBC = complete blood count; GBS = group B streptococcus.
Adapted from Bradley JS, Nelson JD: Nelson's Pediatric Antimicrobial Therapy, ed. 24. Itasca, American Academy of Pediatrics, 2018.

Recommended Dosages of Select Aminoglycosides for Neonates

			Interval of Administration
Aminoglycoside	Route of Administration	Individual Dose	< 30 Week Gestation		30–34 Week Gestation		≥ 35 Week Gestation		Comments
			Postnatal Age		Postnatal Age		Postnatal Age
			0–14 days	> 14 days	0–10 days	> 10 days	0–7 days	> 7 days
Amikacin*	IV, IM	15–17 mg/kg	15 mg/kg every 48 hours	15 mg/kg every 24 hours	15 mg/kg every 24 hours	15 mg/kg every 24 hours	15 mg/kg every 24 hours	17.5 mg/kg every 24 hours	Monitoring of serum drug levels required Peak level target 20–35 mg/L (34.2–59.8 micromol/L) or 10 × MIC; trough < 7 mg/L (12 micromol/L) Dose reduction required for impaired renal function
Gentamicin*, tobramycin	IV, IM	4–5 mg/kg	5 mg/kg every 48 hours	5 mg/kg every 36 hours	5 mg/kg every 36 hours	5 mg/kg every 36 hours	4 mg/kg every 24 hours	5 mg/kg every 24 hours	Monitoring of serum drug levels required Peak level target 6–12 mg/L (12.5–25.1 micromol/L) or 10 × MIC; trough < 2 mg/L (4.2 micromol/L) Dose reduction required for impaired renal function
* Sample should be obtained 30 minutes after a 30-minute IV infusion.
MIC = minimum inhibitory concentration.
Adapted from Bradley JS, Nelson JD: Nelson's Pediatric Antimicrobial Therapy, ed. 24. Itasca, American Academy of Pediatrics, 2018.

Vancomycin Dosage for Neonates

Serum Creatinine (mg/dL)		Dose* (IV)	Interval of Administration
≤ 28 Week Gestation	> 28 Week Gestation	Dose* (IV)	Interval of Administration
< 0.5	< 0.7	15 mg/kg	Every 12 hours
0.5–0.7	0.7–0.9	20 mg/kg	Every 24 hours
0.8–1	1–1.2	15 mg/kg	Every 24 hours
1.1–1.4	1.3–1.6	10 mg/kg	Every 24 hours
> 1.4	> 1.6	15 mg/kg	Every 48 hours
* Dose is given by slow IV infusion, over at least 60 minutes. Begin with a 20 mg/kg loading dose. Ideally, adjust dosage to achieve 24 hours AUC:MIC of 400 mg • hours/L. If this calculation cannot be done, monitor serum trough level (target typically = 10–12 mcg/mL [6.9–8.3 micromol/L]).
AUC = area under the plasma concentration–time curve; MIC = minimum inhibitory concentration.
Adapted from Bradley JS, Nelson JD: Nelson's Pediatric Antimicrobial Therapy, ed. 24. Itasca, American Academy of Pediatrics, 2018.

Recommended Dosages of Selected Oral Antibiotics for Neonates*

		Interval of Administration
Antibiotic	Dose	Body Weight ≤ 2000 g†		Body Weight > 2000 g		Comments
		Postnatal Age		Postnatal Age
		≤ 7 days	8–28 days	≤ 7 days	8–28 days
Amoxicillin (may be combined with clavulanate)	15 mg/kg	—	—	Every 12 hours	Every 12 hours	Limited data for use in neonates < 2000 g Higher doses may be used for severe infections or anthrax Use only the 125 mg/5 mL suspension if combined with clavulanate
Azithromycin	10 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	Preferred drug for treatment or prevention of pertussis in neonates < 1 month; 10 mg/kg given once/day for 5 days May be used for treatment of chlamydial ophthalmia, most commonly 20 mg/kg every 24 hours for 3 days Associated with idiopathic hypertrophic pyloric stenosis, but less commonly than with erythromycin
Clindamycin	5–9 mg/kg	5 mg/kg every 8 hours	5 mg/kg every 8 hours	7 mg/kg every 8 hours	9 mg/kg every 8 hours	Limited data
Erythromycin	10 mg/kg	Every 6 hours	Every 6 hours	Every 6 hours	Every 6 hours	For chlamydial infections or pertussis in neonates > 1 month Associated with idiopathic hypertrophic pyloric stenosis
Fluconazole						Loading dose of 25 mg/kg followed 24 hours later by maintenance dose listed During the 1st 2 weeks of life, adjustment of dosing interval to every 48 hours may be necessary
For treatment	12 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	For minor candidal infections (eg, thrush), 6 mg/kg on day 1, then 3 mg/kg/dose every 24–72 hours
For prophylaxis	6 mg/kg	Twice/week	Twice/week	Twice/week	Twice/week
Flucytosine	25 mg/kg	Every 8 hours	Every 6 hours	Every 6 hours	Every 6 hours	Limited data Used only with amphotericin B to slow emergence of resistance Dosing interval may need to be increased with abnormal renal function Monitoring of levels recommended Desired serum concentrations: Peak 50–100 mg/L, trough 25–50 mg/L
Linezolid	10 mg/kg	Every 12 hours	Every 8 hours	Every 8 hours	Every 8 hours	Used for resistant gram-positive infections
Metronidazole	7.5–10 mg/kg	7.5 mg/kg every 12 hours	7.5 mg/kg every 12 hours	7.5 mg/kg every 8 hours	10 mg/kg every 8 hours	Loading dose 15 mg/kg Limited data
Rifampin	10 mg/kg	Every 24 hours	Every 24 hours	Every 24 hours	Every 24 hours	For treatment Additional dosing regimens may be used for Haemophilus influenzae type b and meningococcal disease prophylaxis
* Unless otherwise stated, doses are for neonates (≤ 28 days postnatal age).
† Use ≤ 7 days dosing until 14 days old if the birth weight is < 1000 g.
Adapted from Bradley JS, Nelson JD: Nelson's Pediatric Antimicrobial Therapy, ed. 24. Itasca, American Academy of Pediatrics, 2018.

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Antibiotics in Neonates

Recommended Dosages of Selected Parenteral Antibiotics for Neonates

Recommended Dosages of Select Aminoglycosides for Neonates

Vancomycin Dosage for Neonates

Recommended Dosages of Selected Oral Antibiotics for Neonates*

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Antibiotics in Neonates

Recommended Dosages of Selected Parenteral Antibiotics for Neonates

Recommended Dosages of Select Aminoglycosides for Neonates

Vancomycin Dosage for Neonates

Recommended Dosages of Selected Oral Antibiotics for Neonates*

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