What is the composition of the ampicillin‑sulbactam 1.5 g preparation?

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Last updated: September 2, 2026 • View editorial policy

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Ampicillin-Sulbactam 1.5 g Composition

The 1.5 g preparation of ampicillin-sulbactam contains 1 gram of ampicillin (as the sodium salt) combined with 0.5 grams of sulbactam (as the sodium salt), in a fixed 2:1 ratio 1.

Detailed Formulation

The combination is formulated as:

  • Ampicillin sodium: 1 gram (1000 mg)
  • Sulbactam sodium: 0.5 grams (500 mg)
  • Total weight: 1.5 grams per dose
  • Sodium content: Approximately 115 mg (5 mEq) of sodium per 1.5 g dose 1

Physical Characteristics

The preparation is supplied as a white to off-white dry powder that requires reconstitution 1. When reconstituted:

  • Forms pale yellow to yellow solutions
  • pH range: 8.0 to 10.0
  • Freely soluble in aqueous diluents
  • Standard concentration after reconstitution: 250 mg ampicillin per mL and 125 mg sulbactam per mL 1

Chemical Structure

Ampicillin sodium is chemically monosodium (2S, 5R, 6R)-6-[(R)-2-amino-2-phenylacetamido]-3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate, with molecular formula C₁₆H₁₈N₃NaO₄S and molecular weight of 371.39 1.

Sulbactam sodium is sodium penicillinate sulfone; sodium (2S, 5R)-3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4-dioxide, with molecular formula C₈H₁₀NNaO₅S and molecular weight of 255.22 1.

Clinical Dosing Context

This 1.5 g formulation represents the standard adult dose administered every 6 hours for most infections 1. The fixed 2:1 ratio (ampicillin:sulbactam) is maintained across all dose strengths, with higher doses (3 g) containing 2 g ampicillin plus 1 g sulbactam 1.

References

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