UNASYN

Indications

• Bacterial infections
• Respiratory tract infections
• Urinary tract infections
• Skin and soft tissue infections
• Intra-abdominal infections

Dosage

Children: Refer to the BNF for Children for appropriate dosing recommendations

Adults: Refer to the BNF for specific dosing guidelines based on the infection type and severity.

Mechanism of action

Sultamicillin works by inhibiting the synthesis of bacterial cell walls. Ampicillin, a penicillin derivative, binds to penicillin-binding proteins (PBPs) located inside the bacterial cell wall, disrupting the transpeptidation process necessary for cell wall structural integrity. Sulbactam, a beta-lactamase inhibitor, protects ampicillin from hydrolysis by certain bacteria that produce beta-lactamase enzymes, thus enhancing the efficacy of the ampicillin component.

Pharmacodynamics

The pharmacodynamics of sultamicillin involve its bactericidal action against susceptible bacteria. It achieves this by interfering with bacterial cell wall synthesis, leading to cell lysis and death. The addition of sulbactam broadens the spectrum of activity against organisms that would otherwise be resistant to ampicillin alone. The combination therapy increases the likelihood of therapeutic success in polymicrobial infections.

Pharmacokinetics

Sultamicillin is administered intravenously or intramuscularly, leading to rapid absorption. Once in circulation, it is distributed throughout body tissues and fluids. The bioavailability is high, with peak plasma concentrations reached shortly after administration. Sultamicillin is metabolized in the liver, and its metabolites, along with some unchanged drug, are excreted primarily through the kidneys. The half-life of sultamicillin is approximately 1 to 2 hours, necessitating multiple doses for sustained therapeutic effects.

Contra-indications

• Hypersensitivity to sultamicillin, penicillins or any of the excipients
• History of severe allergic reactions to beta-lactam antibiotics

Adverse effects

• Gastrointestinal disturbances such as nausea, vomiting, and diarrhea
• Allergic reactions including rash and urticaria
• Hematological reactions such as eosinophilia and thrombocytopenia
• Liver enzyme elevations
• Superinfection due to prolonged use

Interactions

• Anticoagulants - sultamicillin may enhance the effects of anticoagulants
• Probenecid - may increase sultamicillin levels by decreasing renal excretion
• Other antibiotics - may have additive or antagonistic effects

Precautions

• Renal impairment - dosage adjustments may be necessary
• History of gastrointestinal disease, particularly colitis
• Use with caution in patients with liver impairment
• Monitor for signs of superinfection during prolonged therapy

Pregnancy

Sultamicillin should be used in pregnancy only if the potential benefit justifies the potential risk to the fetus. Consult relevant guidelines and clinical judgment.

Breast-feeding

Sultamicillin is excreted in breast milk, and caution should be exercised when administering to nursing mothers. Monitor infant for possible side effects.

Storage

Store below 25°C. Protect from moisture and light. Keep out of reach of children.

Formulations

• Oral tablets
• Injectable solution