Pediatric dosing of antimicrobials

Antibiotics

Penicillins

Drug	Indication	Age	Weight	Usual 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	Weight	Usual 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)