Pediatric dosing of antimicrobials

Antibiotics

Penicillins

Drug	Indication	Age and weight	Dose
Penicillin G IV/IM	moderate to severe infections		100,000 to 400,000 U/kg/day split q4-6h (max 24 MU/day)
	meningitis		400,000 U/kg/day split q4h (max 24 MU/day)
Penicillin VK PO	mild to moderate infections		25-50 mg/kg/day split q8-12h
	rheumatic fever (treatment)	≤ 27 kg	300 mg PO bid x10 days
		> 27 kg	600 mg PO bid x 10 days
	rheumatic fever (prophylaxis)	> 5 years	300 mg PO bid
	asplenia (prophylaxis)	6 months to 5 years	150 mg PO bid
		> 5 years	300 mg PO bid
Cloxacillin IV	methicillin-susceptible Staphylococcus aureus		100-200 mg/kg/day split q4-6h (max 2g/dose and 12 g/day)
Cloxacillin PO			use cephalexin instead
Ampicillin IV	usual dose	neonates	100-200 mg/kg/day split q6-8h
		infants and children	100-200 mg/kg/day split q6h (max 2 g/dose)
	meningitis	neonates	300 mg/kg/day split q6-8h
		infants and children	300-400 mg/kg/day split q4-6h (max 2 g/dose)
Amoxicillin PO	usual dose		40-50 mg/kg/day split q8h
	Streptococcus pneumoniae		80-90 mg/kg/day split q8h
	Group A Streptococcus pharyngitis		50 mg/kg once daily x10 days (max 1 g/dose)
Amoxicillin-clavulanic acid PO	usual dose		30-50 mg/kg/day (amox component) split q8-12h (max 875 mg/dose)
	Streptococcus pneumoniae		80-90 mg/kg/day (amox component) split q8-12h (max 875 mg/dose)
Piperacillin-tazobactam IV	usual dose		240-300 mg/kg/day (pip component) split q6-8h
	Pseudomonas aeruginosa or cystic fibrosis		400 mg/kg/day split q6h

Cephalosporins

Drug	Indication	Age and weight	Dose
First generation
Cefazolin IV/IM	usual dose		75-150 mg/kg/day split q8h (max 2 g/dose and 6 g/day)
Cephalexin PO	usual dose		25-100 mg/kg/day split qid
	osteomyelitis (oral step-down)		100-150 mg/kg/day split qid
Second generation
Cefuroxime IV/IM	usual dose		100-150 mg/kg/day split q8h (max 2 g/dose)
Cefuroxime azetil PO			poor bioavailability; not recommended
Cefprozil PO	usual dose		15-30 mg/kg/day split bid (max 1 g/day)
Third generation
Cefotaxime IV/IM	usual dose	0-7 days	50 mg/kg/dose q8h
		>7 days	50 mg/kg/dose q8h
		infants and children	100-200 mg/kg/day split q6-8h (max 6 g/day)
	meningitis	0-7 days	50 mg/kg/dose q8h
		>7 days	50 mg/kg/dose q6h
		infants and children	200-300 mg/kg/day split q6h (max 4 g/dose and 12 g/day)
Ceftriaxone IM/IV	usual dose	>1 month	50-75 mg/kg q24h (max 2 g/day)
	meningitis	>1 month	100 mg/kg/day split q12-24h (max 2 g/dose and 4 g/day)
	gonorrhea	≥9 years	250 mg IM once
		<9 years	50 mg/kg IM once (max 250 mg)
Ceftazidime IM/IV	usual dose		75-150 mg/kg/day split q8h (max 2 g/dose and 6 g/day)
	meningitis or cystic fibrosis		200 mg/kg/day split q6-8h (max 6 g/day)
Cefixime PO	usual dose		8 mg/kg/day split q12-24h (max 400 mg/day)

Carbapenems

Drug	Indication	Age and weight	Dose
Meropenem	usual dose		20 mg/kg/dose q8h (max 1 g/dose)
	meningitis		40 mg/kg/dose q8h (max 2 g/dose)
Ertapenem	usual dose	3 months to 12 years	15 mg/kg/dose q12h (max 500 mg/dose)
		≥13 years	1 g daily

Glycopeptides

Drug	Indication	Age and weight	Dose
Vancomycin IV	usual dose		40-60 mg/kg/day split q6-12h (max 2+ g/day)
	meningitis or MRSA		60 mg/kg/day split q6-8h (max 4 g/day)
Vancomycin PO	Clostridium difficile		10 mg/kg/dose q6h (max 125 mg/dose)

Macrolides

Drug	Indication	Age and weight	Dose
Clarithromycin PO	usual dose		7.5 mg/kg/dose bid
Azithromycin PO/IV	usual dose		10 mg/kg (max 500 mg) once, then 5 mg/kg (max 250 mg) daily for 4 days
	pertussis	<6 months	10 mg/kg q24h for 5 days
		≥6 months	10 mg/kg once (max 500 mg) then 5 mg/kg dailys (max 250 mg)
	chlamydia	<9 years	20 mg/kg (max 1 g) once
		≥9 years	1 g once
	chlamydial conjunctivitis	infants	20 mg/kg once daily for 3 days