1. Clinical Overview
Meropenem (1000mg) + Sulbactam (500mg) is a fixed-dose combination injectable antibiotic. Meropenem is a broad-spectrum carbapenem beta-lactam antibiotic with potent bactericidal activity against a wide range of Gram-positive, Gram-negative, and anaerobic bacteria. Sulbactam is a beta-lactamase inhibitor that irreversibly binds to and inactivates many beta-lactamase enzymes (including Ambler Class A, C, and some D enzymes), thereby protecting meropenem from degradation and extending its spectrum to include many resistant pathogens. This combination is particularly valuable in the Indian context for treating severe hospital-acquired infections, including those caused by multi-drug resistant (MDR) and extended-spectrum beta-lactamase (ESBL)-producing organisms.
| Onset | Duration | Bioavailability |
|---|---|---|
| Rapid; bactericidal action begins within 1-2 hours of administration. | Dose-dependent; requires administration every 6-8 hours to maintain therapeutic plasma concentrations above the MIC for target pathogens. | 100% via intravenous (IV) administration; not absorbed orally. |
2. Mechanism of Action
Meropenem exerts its bactericidal effect by binding to penicillin-binding proteins (PBPs), particularly PBP-2, on the bacterial cell wall. This inhibits the final transpeptidation step of peptidoglycan synthesis, leading to cell lysis and death. Sulbactam has weak intrinsic antibacterial activity against some Acinetobacter species but primarily functions as an irreversible, competitive inhibitor of a wide range of beta-lactamase enzymes (including TEM-1, SHV-1, and many ESBLs). By binding covalently to these enzymes, it prevents them from hydrolyzing and inactivating meropenem, thereby restoring meropenem's activity against beta-lactamase-producing bacteria.
3. Indications & Uses
- Complicated Intra-abdominal Infections (cIAI)
- Complicated Skin and Skin Structure Infections (cSSSI)
- Complicated Urinary Tract Infections (cUTI) including Pyelonephritis
- Hospital-Acquired Pneumonia (HAP) and Ventilator-Associated Pneumonia (VAP)
- Bacterial Meningitis (in pediatric patients >3 months)
- Septicemia and Bacteremia
4. Dosage & Administration
Adult Dosage: 1.5 g (Meropenem 1000mg + Sulbactam 500mg) administered by intravenous (IV) infusion over 15-30 minutes, every 6 to 8 hours. Duration: 5-14 days depending on infection site and severity.
Administration: Reconstitute the vial with sterile Water for Injection. Shake well. Further dilute the reconstituted solution in 100-250 mL of a compatible IV fluid (0.9% Sodium Chloride or 5% Dextrose). Administer as an IV infusion over 15-30 minutes. DO NOT administer as an IV bolus push. Do not mix with other medications in the same IV line/syringe. The solution is colorless to light yellow; discard if discolored or contains particulate matter.
5. Side Effects
Common side effects may include:
- Injection site reactions (pain, phlebitis, inflammation)
- Diarrhea (may be non-C. difficile related)
- Nausea, vomiting
- Headache
- Rash, pruritus
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Probenecid | Competitively inhibits renal tubular secretion of meropenem, leading to increased and prolonged plasma concentrations of meropenem. Not recommended for concomitant use. | Major |
| Valproic Acid / Valproate Sodium | Meropenem significantly reduces serum valproic acid levels by inhibiting its glucuronidation and possibly increasing its renal clearance. This can lead to loss of seizure control. Avoid concomitant use; use alternative antibiotics or monitor valproate levels closely. | Major |
| Other seizure threshold lowering drugs (e.g., Theophylline, Fluoroquinolones) | Increased risk of seizures. Use with extreme caution. | Moderate |
| Warfarin | Potential for increased INR and risk of bleeding due to effects on gut flora and possible protein binding displacement. Monitor INR closely. | Moderate |
| Other nephrotoxic drugs (e.g., Aminoglycosides, Vancomycin, Loop Diuretics) | Increased risk of nephrotoxicity. Monitor renal function. | Moderate |
7. Patient Counselling
- DO complete the full course of treatment as prescribed, even if you feel better.
- DO inform all your healthcare providers (doctors, dentists) that you are on this injection.
- DON'T skip doses.
- DON'T take any other medication (including OTC, herbal) without consulting your doctor, especially probenecid or valproic acid.
- DON'T stop the medication abruptly without doctor's advice.
8. Toxicology & Storage
Overdose: Symptoms of overdose would be an extension of the known adverse effects, most notably: Central nervous system effects including convulsions, encephalopathy, myoclonus, and tremor. Exacerbation of gastrointestinal side effects like severe diarrhea. In case of accidental overdose, renal excretion may be increased.
Storage: Unreconstituted vials: Store below 25°C, protected from light and moisture. Keep in the original package. Reconstituted Solution: The solution in the vial is stable for up to 2-3 hours at room temperature (25°C) or up to 12-18 hours if refrigerated (2-8°C), depending on the diluent and manufacturer's instructions. Infusion Solution: Once diluted in IV fluid, use immediately. Stability ranges from 1-4 hours at room temperature and up to 24 hours if refrigerated, depending on the diluent. DO NOT FREEZE. Always inspect for particulate matter and discoloration before administration.