What is the proper way to write an order for ampicillin (Ampicillin)-sulbactam (Sulbactam)?

How to Write an Order for Ampicillin-Sulbactam

For most infections, order ampicillin-sulbactam 1.5-3 g IV every 6 hours (administered over 15-30 minutes), with the specific dose and interval adjusted based on infection severity and renal function. 1

Standard Dosing Format

The order should specify the total combined dose (ampicillin + sulbactam together), not individual components: 1

• 1.5 g IV every 6 hours = 1 g ampicillin + 0.5 g sulbactam 1
• 3 g IV every 6 hours = 2 g ampicillin + 1 g sulbactam 1

Administration Instructions

Route and timing: 1

• IV administration over 15-30 minutes as an infusion (preferred) 1
• Alternative: slow IV push over 10-15 minutes minimum 1
• IM injection is possible but requires different reconstitution 1

Dosing by Clinical Scenario

Severe Infections (Culture-Negative Endocarditis, MDR Organisms)

Order: Ampicillin-sulbactam 3 g IV every 6 hours (total 12 g/day) 2

• This represents the maximum standard dose for severe infections 2, 3
• For endocarditis, combine with gentamicin 3 mg/kg/day IV/IM divided every 8 hours 2
• Duration: 4-6 weeks for endocarditis 2

Multidrug-Resistant Acinetobacter (High-Dose Sulbactam)

Order: Ampicillin-sulbactam 4.5-6 g IV every 8 hours (9-12 g sulbactam/day) as 4-hour extended infusion 4, 5

• This exceeds FDA-labeled dosing but is guideline-recommended for resistant organisms 4
• The 4-hour infusion optimizes pharmacokinetics for MIC ≤4 mg/L 4
• Maximum sulbactam: 12 g/day (not to exceed) 4

Moderate Infections

Order: Ampicillin-sulbactam 1.5 g IV every 6 hours 1

• Appropriate for community-acquired pneumonia, skin/soft tissue infections 1
• Can increase to 3 g every 6 hours if inadequate response 1

Pediatric Dosing (≥1 Year Old)

Order: Ampicillin-sulbactam 300 mg/kg/day IV divided every 6 hours 1

• This equals 200 mg/kg/day ampicillin + 100 mg/kg/day sulbactam 1
• For endocarditis: same 300 mg/kg/day divided every 4-6 hours 2, 3
• Maximum: do not exceed adult dosing in children ≥40 kg 1

Renal Dose Adjustments

Critical pitfall: Both ampicillin and sulbactam are renally eliminated; failure to adjust causes toxicity 1, 6

Dosing by Creatinine Clearance

CrCl (mL/min)	Half-Life	Recommended Dosing
≥30	1 hour	1.5-3 g every 6-8 hours [1]
15-29	5 hours	1.5-3 g every 12 hours [1]
5-14	9 hours	1.5-3 g every 24 hours [1]

Hemodialysis Patients

Order: Ampicillin-sulbactam 1.5-3 g IV every 24 hours, given AFTER dialysis 6

• Hemodialysis removes 35% of ampicillin and 45% of sulbactam over 4 hours 6
• Post-dialysis dosing prevents underdosing 6
• Half-life: 17.4 hours (ampicillin) and 13.4 hours (sulbactam) off dialysis 6

Extended Daily Dialysis (EDD)

Order: Ampicillin-sulbactam 2 g/1 g IV every 12 hours (higher than standard HD dosing) 7

• EDD dramatically increases clearance (half-life only 1.5 hours) 7
• Standard HD dosing causes significant underdosing in EDD patients 7

Anuric Patients (Not on Dialysis)

Order: Ampicillin-sulbactam 1 g/0.5 g IV every 12 hours 8

• Maintains free ampicillin >12 μg/mL (adequate for MSSA prophylaxis) 8
• Half-life extends to 4.2 hours in anuria 8

Common Ordering Pitfalls to Avoid

Pitfall 1: Ordering Individual Components Separately

• Wrong: "Ampicillin 2 g IV + sulbactam 1 g IV" 1
• Correct: "Ampicillin-sulbactam 3 g IV" 1
• The combination is fixed-ratio and should be ordered as a single entity 1

Pitfall 2: Exceeding Maximum Sulbactam Dose

• Maximum sulbactam: 4 g/day for standard dosing 1
• For high-dose regimens (MDR organisms): maximum 12 g/day sulbactam 4
• Exceeding these limits increases seizure risk without added benefit 1

Pitfall 3: Inadequate Infusion Time

• Never give as rapid IV push 1
• Minimum 10-15 minutes for slow injection, preferably 15-30 minutes as infusion 1
• For high-dose regimens: 4-hour extended infusion required 4

Pitfall 4: Not Adjusting for Renal Function

• Failure to reduce frequency in CrCl <30 mL/min causes accumulation 1, 6
• Use Cockcroft-Gault equation if only serum creatinine available 1
• Adjust before second dose in acute kidney injury 7

Pitfall 5: Wrong Timing in Dialysis Patients

• Always dose AFTER hemodialysis, not before 6
• Dosing before dialysis wastes 35-45% of the dose 6

Sample Order Sets

Standard Infection Order

Ampicillin-sulbactam 1.5 g IV every 6 hours
Infuse over 30 minutes
Adjust for renal function per protocol

1

Severe Infection/Endocarditis Order

Ampicillin-sulbactam 3 g IV every 6 hours
Infuse over 30 minutes
PLUS
Gentamicin 3 mg/kg/day IV divided every 8 hours
Duration: 4-6 weeks

2

MDR Acinetobacter Order

Ampicillin-sulbactam 6 g IV every 8 hours
Infuse over 4 hours (extended infusion)
Maximum daily sulbactam: 12 g

4, 5

Hemodialysis Patient Order

Ampicillin-sulbactam 1.5 g IV every 24 hours
Give AFTER dialysis on dialysis days
Infuse over 30 minutes

6