Imbac(500 mg+500 mg)/vial

Imbac is a broad-spectrum carbapenem antibiotic combination indicated for the treatment of serious bacterial infections caused by susceptible organisms, particularly when multi-drug-resistant or polymicrobial pathogens are suspected or confirmed. Because of its broad spectrum and role as a reserve/last-line agent, it is generally used for moderate to severe infections rather than as first-line therapy for mild infections.

Established / FDA-approved uses

• Lower respiratory tract infections (including pneumonia)
• Complicated and uncomplicated urinary tract infections
• Intra-abdominal infections
• Gynecologic infections (e.g., endometritis, pelvic inflammatory disease)
• Bacterial septicemia (bloodstream infections)
• Bone and joint infections
• Skin and skin-structure infections
• Endocarditis caused by susceptible organisms
• Polymicrobial infections involving both aerobic and anaerobic organisms

Guideline-supported / adjunct use

• Empiric therapy in febrile neutropenic patients, generally as part of an institutional protocol and sometimes combined with other antimicrobials depending on local resistance patterns.

Note: Imbac is not recommended for the treatment of meningitis because of an increased risk of seizures with poor central nervous system tolerability, and it should be reserved for infections where susceptibility testing supports its use whenever possible, consistent with antimicrobial stewardship principles.

Each vial of Imipenem + Cilastatin for injection contains imipenem (as imipenem monohydrate) and cilastatin (as cilastatin sodium) in a 1:1 ratio by weight, typically available in strengths such as 250 mg/250 mg and 500 mg/500 mg per vial for intravenous use. Cilastatin has no antibacterial activity of its own; it is included solely to inhibit renal metabolism of imipenem.

Imbac is a fixed-dose combination antibiotic product consisting of imipenem, a carbapenem-class beta-lactam antibiotic, and cilastatin, a renal dehydropeptidase-I inhibitor. Imipenem alone is rapidly broken down by an enzyme in the kidney (dehydropeptidase-I), which would otherwise limit its urinary concentration and clinical usefulness; cilastatin blocks this enzyme, allowing imipenem to remain active and reach therapeutic concentrations in blood and urine. Imbac is administered by intravenous infusion in a hospital or supervised clinical setting and is used against a wide range of gram-positive, gram-negative, and anaerobic bacteria.

Imbac belongs to the carbapenem class of beta-lactam antibiotics, combined with a renal dehydropeptidase inhibitor. It is classified as a broad-spectrum, reserve-line antibacterial agent.

Imipenem is a carbapenem antibiotic that exerts bactericidal activity by binding to penicillin-binding proteins (PBPs) on the bacterial cell wall, inhibiting cell wall synthesis and leading to bacterial cell lysis and death. It has activity against a broad range of gram-positive and gram-negative aerobic and anaerobic bacteria.

Cilastatin has no intrinsic antibacterial activity. It works by competitively inhibiting renal dehydropeptidase-I, the enzyme in the brush border of the renal tubules that would otherwise rapidly hydrolyze and inactivate imipenem. By blocking this metabolism, cilastatin increases the amount of active imipenem available in the urinary tract and systemic circulation, which is why the two are always combined in Imipenem + Cilastatin.

Imbac is reconstituted and further diluted according to the manufacturer's instructions and administered as an intravenous infusion, never as an intramuscular or rapid intravenous bolus injection for the intravenous formulation. Doses of 250 mg or 500 mg are typically infused over approximately 20-30 minutes, while doses of 1 g are infused over approximately 40-60 minutes, to reduce the risk of infusion-related nausea and vomiting. If nausea occurs during infusion, the infusion rate may be slowed.

The following are well-documented, clinically significant interactions with Imbac:

Valproic acid / divalproex sodium

Concomitant use of carbapenems, including Imbac, with valproic acid or divalproex sodium can cause a significant reduction in valproic acid serum concentrations, sometimes below the therapeutic range, resulting in loss of seizure control and breakthrough seizures. This combination should generally be avoided; if concurrent use cannot be avoided, valproic acid levels should be monitored closely and alternative anticonvulsant or antibacterial therapy considered.

Ganciclovir

Concurrent use of Imbac with ganciclovir has been associated with an increased risk of generalized seizures. This combination should be used only if the potential benefit outweighs the risk.

Probenecid

Probenecid competes with imipenem for renal tubular secretion, increasing plasma concentrations and prolonging the half-life of imipenem when co-administered with Imbac; this combination offers little clinical advantage and is generally not recommended.

Common and important adverse effects reported with Imbac include:

• Gastrointestinal: nausea, vomiting, diarrhea (including the possibility of Clostridioides difficile-associated diarrhea/colitis)
• Local reactions: pain, erythema, and phlebitis/thrombophlebitis at the injection site
• Skin: rash, pruritus, urticaria
• Hypersensitivity reactions, including rare anaphylaxis (see Contraindications)
• Central nervous system: seizures, myoclonic activity, confusion, dizziness, particularly at higher doses, in patients with CNS disorders, or with renal impairment and inadequate dose adjustment (see Precautions and Warnings)
• Laboratory abnormalities: elevated liver transaminases, eosinophilia, changes in blood counts
• Fever

Patients should seek prompt medical attention for signs of a severe allergic reaction, seizures, or severe/persistent diarrhea.

Data on the use of Imbac in human pregnancy are limited. It should be used during pregnancy only if clearly needed and if the potential benefit to the mother from treating a serious infection justifies the potential, though not well-established, risk to the fetus; a physician should be consulted before use in pregnancy.

Imbac is excreted in human breast milk in small amounts. Caution is advised when administering to a breastfeeding woman; a physician should weigh the benefit of treatment against the potential for effects on the breastfed infant, such as diarrhea or effects on infant gut flora.

Seizure risk: Imbac has been associated with central nervous system adverse effects, most notably seizures, more frequently than some other antibiotics. The risk is higher with higher doses, in patients with a history of seizure disorders or other CNS abnormalities, and in patients with renal impairment in whom the dose has not been appropriately reduced. Careful adherence to renal dosing recommendations is essential, and anticonvulsant therapy should be continued in patients with known seizure disorders.

Hypersensitivity and cross-reactivity: See Contraindications for details on beta-lactam cross-reactivity.

Clostridioides difficile-associated diarrhea: As with other broad-spectrum antibiotics, Imbac can cause overgrowth of C. difficile, resulting in diarrhea ranging from mild to life-threatening colitis; this should be considered in any patient who develops diarrhea during or after treatment.

Renal impairment: Dose adjustment is required based on creatinine clearance; use in severe renal impairment requires specialist guidance (see Dosage and Administration).

Not for meningitis: Imbac is not recommended for the treatment of meningitis due to an increased seizure risk and limited central nervous system penetration data.

Antibiotic stewardship: Take exactly as prescribed by your physician; do not stop, extend, skip doses, or share this medicine with others without medical advice.

There is no specific antidote for Imbac overdose. In the event of a suspected overdose, seek immediate medical attention or contact emergency services/a poison control center. Overdose may increase the risk of nausea, vomiting, and seizures, especially in patients with renal impairment. Management is supportive; hemodialysis can help remove imipenem and cilastatin from the circulation and may be considered in significant overdose, particularly in patients with renal failure, under medical supervision.

Store the unreconstituted powder for injection at room temperature (below 30°C), protected from light and moisture. Once reconstituted or further diluted for infusion, use promptly as directed by the pharmacist/manufacturer's instructions, or refrigerate and use within the specified time window; do not freeze reconstituted solutions unless specifically directed. Keep out of reach of children.

Renal impairment: Dose and dosing interval of Imbac must be adjusted based on creatinine clearance; use in patients with severe renal impairment who are not on hemodialysis is generally avoided due to increased seizure risk (see Dosage and Administration, and Precautions and Warnings).

Hepatic impairment: No specific dose adjustment is generally required, but liver function should be monitored, as elevated liver enzymes have been reported.

Elderly: No specific age-based dose adjustment beyond that required for age-related decline in renal function; renal function should be assessed and dosing adjusted accordingly.

Pediatric patients: Use in children 3 months of age and older is established for non-CNS infections at weight-based doses (see Dosage). Safety and efficacy in infants younger than 3 months, and use for CNS infections such as meningitis, have not been established, and use in these situations should be avoided or undertaken only under specialist supervision.

The duration of treatment with Imbac depends on the type, site, and severity of the infection, the causative organism, and the patient's clinical response, and is determined by the treating physician. Typical courses range from about 5 to 14 days; more complicated infections such as endocarditis or bone/joint infections may require longer courses. Treatment should not be stopped early even if symptoms improve, unless advised by a physician, to reduce the risk of relapse or resistance.

Imbac powder for injection must be reconstituted before use. For intravenous infusion, the contents of the vial are first reconstituted with a small volume of a compatible diluent (such as 0.9% sodium chloride injection) and shaken to form a suspension, which is then transferred into the appropriate volume of infusion fluid to achieve the required concentration, following the manufacturer's instructions and using proper aseptic technique. The reconstituted admixture should be inspected visually for particulate matter and discoloration prior to administration and used within the time period specified by the manufacturer, or refrigerated if administration is delayed.

Carbapenem antibiotic (imipenem) combined with a renal dehydropeptidase-I inhibitor (cilastatin).

Imipenem inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins, causing cell wall damage and bacterial death (bactericidal action) across a broad range of gram-positive, gram-negative, and anaerobic organisms. Cilastatin itself has no antibacterial activity; it works by inhibiting renal dehydropeptidase-I, the enzyme that would otherwise rapidly degrade imipenem in the kidney, thereby preserving imipenem's activity and allowing it to reach effective concentrations in the body. This is why imipenem is never used alone and is always paired with cilastatin, as in Imipenem + Cilastatin.

Imbac may be used in children 3 months of age and older for non-central nervous system infections, at weight-based doses adjusted for age and renal function (see Dosage). Safety and efficacy have not been established in infants younger than 3 months of age. Imbac is not recommended for the treatment of pediatric meningitis or other CNS infections because of an increased risk of seizures and inadequate data on CNS penetration and safety in this setting. Use in children should always be supervised by a pediatrician or specialist physician.