IV Unasyn Dosing for Infected Sacral Ulcers and Aspiration Pneumonia
For a 70-year-old man with infected sacral ulcers with purulent drainage and aspiration pneumonia with normal renal function, administer IV Unasyn (ampicillin/sulbactam) 3 g every 6 hours (2 g ampicillin + 1 g sulbactam per dose). 1, 2
Dosing Rationale
The standard adult dose for moderate-to-severe infections is 1.5-3 g IV every 6 hours, with the higher end of this range (3 g every 6 hours) recommended for this patient given the dual serious infections involving both skin/soft tissue and respiratory tract. 1, 2
Why 3 g Every 6 Hours is Appropriate:
For aspiration pneumonia requiring hospitalization (moderate severity), the recommended dose is ampicillin/sulbactam 1.5-3 g IV every 6 hours to provide adequate anaerobic coverage. 1
For complicated skin and soft tissue infections (which infected sacral ulcers with purulent drainage represent), the recommended dose is 1.5-3 g IV every 6 hours. 3
The FDA label specifies that the total sulbactam dose should not exceed 4 grams per day, which is satisfied by 3 g every 6 hours (providing 4 g sulbactam daily). 2
Administration Details
Administer each dose as a slow IV infusion over 15-30 minutes, diluted in 50-100 mL of compatible diluent. 2
With normal renal function (creatinine clearance >30 mL/min), no dose adjustment is required and the standard every 6-hour interval should be maintained. 2
Treatment Duration
Continue therapy for 5-7 days if the patient becomes afebrile for 48 hours and reaches clinical stability. 1
For aspiration pneumonia, typical duration is 5-7 days for responding patients. 1
Daily assessment for clinical response at 48-72 hours is mandatory to determine if therapy should be continued, de-escalated, or changed. 4
Critical Considerations for This Patient
Elderly patients (≥65 years) may have altered pharmacokinetics with prolonged half-life and increased volume of distribution, but with normal renal function, standard dosing remains appropriate. 5
The combination provides coverage for:
- Anaerobic pathogens critical for aspiration pneumonia 1
- Mixed aerobic-anaerobic flora typical of infected pressure ulcers with purulent drainage 3
- Common respiratory pathogens including Streptococcus pneumoniae and Haemophilus influenzae 1
Monitoring Parameters
Assess clinical response at 48-72 hours; if no improvement, reassess diagnosis or consider alternative therapy. 6
Monitor renal function during therapy, as elderly patients may develop changes in creatinine clearance requiring dose adjustment. 2, 5
Evaluate for adequate source control of the sacral ulcers, as surgical debridement may be necessary if there is no clinical improvement. 3
Common Pitfalls to Avoid
Do not use ampicillin alone, as it lacks adequate H. influenzae coverage for pneumonia. 1
Do not underdose at 1.5 g every 6 hours when treating dual serious infections—use the higher 3 g dose. 1, 4
Do not extend the dosing interval to every 8 hours in this patient with normal renal function, as every 6-hour dosing is required for optimal pharmacodynamic targets. 2
Do not continue therapy beyond 7-10 days without reassessing for complications or alternative diagnoses if clinical response is inadequate. 4