C. diff Risk


Oral Bioavailability


Approximate Cost

$11.64/day (IV)


1-2g IV q4-6h

2g IV q4h for meningitis or endocarditis

General Information

Common Usage

Pathogen directed therapy for CNS, intravascular, intraabdominal, urinary and other infections especially Enterococcus and Listeria

Adverse Effects

Allergy and rash as for all beta-lactams.

EBV related rash (not allergy).

Rare: cytopenias, +ve Coombs.

Major Interactions

Increased risk of rash with allopurinol.

Tablet/Capsule Strengths

No prescribing restrictions

Additional Information

IV Administration

  • Dilute in 50-100 mL NS and administer over 30 min.

  • Max concentration 30 mg/mL.

Prescribing Restrictions (IV)

  • None

  • Ampicillin PO orders are automatically substituted with Amoxicillin PO at Eastern Health

Community IV Formulary (St. John’s Metro)

  • NO

  • Limited Stability of IV ampicillin precludes use in Community IV program.


Antimicrobial class: Aminopenicillin

Pregnancy category: B

Average serum half life: 1 hour

Biliary penetration: Therapeutic

CSF penetration: Therapeutic

Lung penetration: Therapeutic

Urine penetration: Therapeutic