Neonatal Drug Therapy Manual


Disclaimer: Official controlled document is the CHEO and Ottawa Hospital online copy. It is the responsibility of user to ensure that any paper copy version is the same as the online version before use.

Antibiotic (semi-synthetic penicillin)
Original Date: 
March 1993
Revised Date: 
Nov 2023
  • Infections due to most Gram (+) and Gram (-) aerobic cocci
  • Infections due to some Gram (+) aerobic and anaerobic bacilli and some spirochetes
  • IV direct: over 5 minutes.  Do not exceed infusion rate of 10 mg/kg/minute.
  • IV intermittent infusion: over 15 - 30 minutes.
  • Usual IV dilution: 125 mg/mL (CHEO) , 100 mg/mL (TOH)
  • IM



Group B Streptococcal Meningitis

0-7 days:   2 kg

                   > 2 kg

100 mg/kg/day divided Q12H

150 mg/kg/day divided Q8H

Regardless of weight:
200 - 300 mg/kg/day divided Q8H

>7 days:   < 1.2 kg

                   1.2-2 kg

                     > 2 kg

100 mg/kg/day divided Q12H 

150 mg/kg/day divided Q8H

200 mg/kg/day divided Q6H

Regardless of weight:
300 mg/kg/day divided 4-6H*

* Doses up to 400 mg/kg/day have been used

Dosage adjustment required in renal impairment.  Refer to available references or clinical pharmacist for dosage adjustment.

Side Effects: 
  • CNS: excitation/seizure with very high doses
  • GI: diarrhea
  • Hematologic: thrombocytopenia, leukopenia, neutropenia, agranulocytosis
  • Local: may be irritating to veins
Parameters to Monitor: 
  • CBC with differential
  • Temperature
  • Injection site
Reconstitution and Stability: 


Reconstituted vials: use within 1 hour; 4 hr stability in fridge 

Ampicillin 500 mg

  • Add 4 mL SWFI
  • Final concentration: 125 mg/mL



Reconstituted vials: use within 1 hour

Ampicillin 250 mg

  • Add 2.5 mL SWFI
  • Final concentration: 100 mg/mL

Ampicillin 500 mg

  • Add 5 mL SWFI
  • Final concentration: 100 mg/mL


Ampicillin 250 mg

  • Add 0.9 mL SWFI
  • Final concentration: 250 mg/mL

 Ampicillin 500 mg

  • Add 1.8 mL SWFI
  • Final concentration: 250 mg/mL

- Solutions Compatible:  0.9% NaCl

- Y-site Compatible: heparin, morphine, potassium chloride, SMOF

- Incompatible: dopamine, epinephrine, gentamicin, midazolam, TPN, vancomycin. Dextrose IV fluids are generally considered incompatible with ampicillin; D5W has been used, but for a maximum of 1 hour contact with ampicillin if necessary. 


Contains 2.6 - 3.1 mmol Na/g (according to the brand).  May interfere with results of Clinitest (false positive result).


-Taketomo CK, Hodding JH, Kraus DM. Pediatric Dosage Handbook 22nd Edition. Hudson: Lexi-Comp Inc.; 2015

-Trissel LA. Handbook on Injectable Drugs. 16th Edition. Bethesda: American Society of Health-System Pharmacists; 2011

- Lau E, Chen Jennifer. (Editors). Drug Handbook and Formulary - The Hospital for Sick Children. Toronto: Lexi-Comp Inc.; 2015

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