While ampicillin for injection, USP, 1 g and 2 g, are primarily for intravenous use, they may be administered
intramusculary when the 250 mg or 500 mg vials are unavailable. In such instances, dissolve in 3.5 or
6.8 mL Sterile Water for Injection, USP, or Bacteriostatic Water for Injection, USP, respectively. The resulting
solution will provide a concentration of 250 mg per mL.
Ampicillin for injection, USP, 125 mg, is intended primarily for pediatric use. It also serves as a convenient
dosage form when small parenteral doses of the antibiotic are required.