Ampicillin and sulbactam are both hydrophilic antibiotics and have a volume of distribution (Vd) similar to the volume of extra-cellular body water. The volume that the drug distributes throughout in healthy patients is approximately 0.2 liters per kilogram of body weight. Patients on hemodialysis, elderly patients, and pediatric patients have shown a slightly increased volume of distribution. Using typical doses, ampicillin/sulbactam has been shown to reach desired levels to treat infections in the brain, lungs, and abdominal tissues. Both agents have moderate protein binding, reported at 38% for sulbactam and 28% for ampicillin.15,16  The half-life of ampicillin is approximately 1 hour, when used alone or in combination with sulbactam; therefore it will be eliminated from a healthy person in around 5 hours. It is eliminated primarily by the urinary system, with 75% excreted unchanged in the urine. Only small amounts of each drug were found to be excreted in the bile. Ampicillin/sulbactam should be given with caution in infants less than a week old and premature neonates. This is due to the underdeveloped urinary system in these patients, which can cause a significantly increased half-life for both drugs.16   Based on its elimination, ampicillin/sulbactam is typically given every 6 to 8 hours. Slowed clearance of both drugs has been seen in the elderly, renal disease patients, and critically ill patients on renal replacement therapy. Reduced clearance has been seen in both pediatric and post-operative patients. Adjustments in dosing frequency may be required in these patients due to these changes.
Anaerobes: Clostridium species, Peptococcus species, Peptostreptococcus species, Bacteroides species including B. fragilis.Gynecological Infections
Ampicillin/sulbactam can be used to treat gynecological infections caused by beta-lactamase producing strains of Escherichia coli, and Bacteroides (including B. fragilis).Bone and joint infections
Ampicillin/sulbactam can be used in the treatment of bone and joint infections caused by susceptible beta-lactamase producing bacteria.Intra-abdominal infections
Ampicillin/sulbactam can be used to treat intra-abdominal infections caused by beta-lactamase producing strains of Escherichia coli, Klebsiella (including K. pneumonia), Bacteroides fragilis, and Enterobacter.Skin and skin structure Infections
This medication can be used to treat skin and skin structure infections caused from beta-lactamase-producing strains of Staphylococcus aureus, Enterobacter, Escherichia coli, Klebsiella (including K. pneumoniae), Proteus mirabilis, Bacteroides fragilis, and Acinetobacter calcoaceticus. Examples of skin conditions treated with ampicillin-sulbactam are moderate to severe diabetic foot infections and type 1 Necrotizing fasciitis, commonly referred to as "flesh-eating bacteria". Contraindications
Ampicillin/sulbactam is contraindicated in individuals who have a history of a penicillin allergy. Symptoms of allergic reactions may range from rash to potentially life-threatening conditions, such as anaphylaxis. Patients who have asthma, eczema, hives, or hay fever are more likely to develop undesirable reactions to any of the penicillins. Adverse effects
Reported adverse events include both local and systemic reactions. Local adverse reactions are characterized by redness, tenderness, and soreness of the skin at the injection site. The most common local reaction is injection site pain. It has been reported to occur in 16% of patients receiving intramuscular injections, and 3% of patients receiving intravenous injections.