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

Aminoglycosides

Drug	Indication	Age and weight	Dose
Tobramycin IV	usual dose		5-7 mg/kg/dose q24h
	cystic fibrosis		10-12 mg/kg/dose q24h
Tobramycin INH	cystic fibrosis		80 mg bid to tid
Gentamicin IV	usual dose	≤7 days	4 mg/kg/dose q24h
		>7 days	5 mg/kg/dose q24h
		infants and children	5-7 mg/kg/dose q24h
	synergy for Gram-positive infections	1 mg/kg/dose q8h

• Extended-frequency dosing of aminoglycosides is preferred for all patients older than 1 month with the exception of endocarditis or extensive burns
• Monitor trough levels pre-second dose, with target of <1 mg/L

Fluoroquinolones

Drug	Indication	Age and weight	Dose
Ciprofloxacin IV/PO	usual dose		20-30 mg/kg/day split q12h (max 400 mg/dose IV or 750 mg/dose PO)
Levofloxacin PO/IV	usual dose	≤5 years	10 mg/kg q12h
		>5 years	10 mg/kg daily (max 750 mg/day)

Miscellaneous

Drug	Indication	Age and weight	Dose
Lincosamides
Clindamycin IV	usual dose		20-40 mg/kg/day split q6h (max 600 mg/dose)
	toxic shock syndrome or necrotizing fasciitis		600-900 mg q8h
Clindamycin PO	usual dose		10-30 mg/kg/day split q6-8h
Nitroimidazole
Metronidazole PO/IV	anaerobic infections		20-30 mg/kg/day split q8-12h (max 1500 mg/day IV or 2000 mg/day PO)
	severe infections		50 mg/kg/day split q8h
	C. difficile infection		30 mg/kg/day split q6-8h (max 1500 mg/day)
Sulfonamides
Co-trimoxazole PO/IV	usual dose		8-10 mg/kg/day TMP split q12h
	MRSA		8-12 mg/kg/day TMP split q12h
	Pneumocystis pneumonia (treatment)		15-20 mg/kg/day TMP split q6-8h
	Pneumocystis pneumonia (prophylaxis)		3-5 mg/kg/day TMP split q12h on Mon-Wed-Fri
Trimethoprim PO	UTI (prophylaxis)		2-3 mg/kg/day split q12h	Others
Nitrofurantoin PO	UTI (treatment)		5-7 mg/kg/day split q6h (max 400 mg/day)
	UTI (prophylaxis)		1-2 mg/kg/day daily
Macrobid PO	UTI (treatment)	>12 years	100 mg bid

Antifungals

Drug	Indication	Age and weight	Dose
Liposomal amphotericin B IV	usual dose		3-5 mg/kg daily
	severe infections		10 mg/kg daily
Caspofungin IV	usual dose		70 mg/m2 once (max 70 mg) followed by 50 mg/m2 daily (max 50 mg)
Nystatin PO	oral candidiasis	infants	100,000 U swish & swallow qid
		children	250,000 U swish & swallow qid
		adolescents	500,000 U swish & swallow qid

Antivirals

Drug	Indication	Age and weight	Dose
Acyclovir IV	HSV and VZV	1-3 month infants	20 mg/kg/dose q8h
	HSV encephalitis	3 months to 12 years	10-15 mg/kg/dose q8h
		>12 years	10 mg/kg/dose q8h
	HSV (severe or immunocompromised)		5-10 mg/kg/dose q8h
	VZV (severe or immunocompromised)		10 m/kg/dose q8h
Acyclovir PO	HSV (mild-moderate and immunocompetent)		30-50 mg/kg/day split 3-5 times daily
	HSV (severe or immunocompromised, step-down)		60-80 mg/kg/day split 3-5 times daily
	VZV (immunocompetent)		80 mg/kg/day split 3-5 times daily
	VZV (severe or immunocompromised, step-down)		80 mg/kg/day split 3-5 times daily