Imipenem/Cilastatin Kabi (Cilastatin Sodium, Imipenem Monohydrate)

Imipenem/cilastatin is used for severe bacterial infections across several organ systems.

• Complicated intra-abdominal infections: effective in treating polymicrobial infections following surgery or perforated viscus.
• Complicated urinary tract infections: clears resistant Gram‑negative pathogens in the urinary tract.
• Hospital‑acquired pneumonia: provides coverage for typical and atypical organisms in nosocomial lung infections.
• Ventilator‑associated pneumonia: used in intubated patients with ventilator‑related lung infection.
• Severe sepsis: administered as part of broad‑spectrum therapy for systemic infection.
• Skin and soft tissue infections: treats deep or necrotizing infections caused by susceptible bacteria.

• Imipenem binds to penicillin‑binding proteins, inhibiting the final stages of bacterial cell‑wall peptidoglycan synthesis, which leads to cell lysis. Cilastatin, co‑administered, inhibits renal dehydropeptidase I, preventing enzymatic degradation of imipenem and thereby maintaining therapeutic concentrations in the bloodstream. The combined effect results in a broad‑spectrum bactericidal activity against Gram‑positive, Gram‑negative and anaerobic organisms, including many resistant strains.

Imipenem/cilastatin may cause a range of adverse reactions, which are categorized by frequency and severity.

Common Side Effects

• Nausea: mild to moderate gastrointestinal upset.
• Vomiting: occasional emesis.
• Diarrhea: may be watery and self‑limiting.
• Rash: mild skin erythema.
• Headache: transient cranial discomfort.
• Elevated liver enzymes: mild transaminase increase.

Serious or Rare Side Effects

• Seizures: risk increased in patients with renal impairment or CNS disorders.
• Anaphylaxis: severe allergic reaction requiring immediate treatment.
• Clostridioides difficile‑associated diarrhea: potentially life‑threatening colitis.
• Stevens‑Johnson syndrome or toxic epidermal necrolysis: severe skin reactions.
• Neutropenia: marked reduction in white blood cells.
• Renal toxicity: acute kidney injury in susceptible individuals.

Before initiating Imipenem/cilastatin therapy, clinicians should consider several safety precautions to minimize risks.

• Renal function: assess creatinine clearance and adjust dose in renal impairment.
• Seizure risk: monitor patients with a history of seizures or CNS disorders.
• Allergy: avoid use in individuals with known hypersensitivity to carbapenems or β‑lactam antibiotics.
• Pregnancy and lactation: prescribe only if potential benefits outweigh potential risks to the fetus or infant.
• Drug interactions: review concomitant medications for possible interactions affecting efficacy or safety.
• Store at 2-8°C: keep refrigerated, protect from light, do not freeze or shake.

Imipenem/cilastatin can interact with other medicines, altering its effectiveness or increasing toxicity.

Major Interactions (Avoid)

• Valproic acid: co‑administration can markedly lower serum valproate concentrations, potentially precipitating breakthrough seizures.
• Probenecid: may decrease renal tubular secretion of imipenem, leading to higher plasma levels and increased toxicity risk.

Moderate Interactions (Monitor Closely)

• Aminoglycosides: concurrent use may increase nephrotoxic risk; monitor renal function and drug levels.
• Loop diuretics: combined therapy can potentiate renal impairment; assess kidney function regularly.
• Anticoagulants (e.g., warfarin): imipenem may affect vitamin K‑dependent clotting factor synthesis; monitor INR and adjust dose as needed.