Meropenem Vaborbactam

Meropenem vaborbactam combines meropenem with a boronic acid beta-lactamase inhibitor. It is a reserve agent for carbapenem-resistant Enterobacterales that produce KPC, and for ESBL and AmpC producers in complicated urinary infection.

Classification. Beta-lactam, carbapenem plus cyclic boronate inhibitor. Doses are written as the combined weight: 2 g contains 1 g meropenem and 1 g vaborbactam.

Mechanism. Meropenem blocks penicillin-binding proteins; vaborbactam inactivates class A (including KPC) and class C enzymes and does not restore activity against metallo-beta-lactamases or most OXA enzymes.

Spectrum. KPC-producing Enterobacterales, ESBL and AmpC producers. Not reliable against Pseudomonas aeruginosa, Acinetobacter, Stenotrophomonas, NDM, VIM or OXA-48 producers, or Gram-positive carbapenem-resistant organisms.

Pharmacokinetics. IV only. Half-life about 1.5 hours for both components. Protein binding 2% for meropenem and 33% for vaborbactam. Over 75% excreted unchanged in urine.

Reserve agent; specialist use. No loading dose.

Adults, creatinine clearance 50 mL/min or more. 4 g (2 g/2 g) IV over 3 hours every 8 hours. - Complicated urinary tract infection including pyelonephritis: up to 14 days. - Off-label (specialist): bacteraemia, pneumonia and intra-abdominal infection with KPC-producing Enterobacterales, at the same dose, with duration set by site.

Children. Not established in most labels.

Alternatives. Ceftazidime avibactam, imipenem cilastatin relebactam, cefiderocol.

Contraindications. Hypersensitivity to carbapenems or any component; severe hypersensitivity to other beta-lactams.

Adverse effects. Headache, infusion-site reactions, diarrhoea, nausea, hypersensitivity, raised liver enzymes. Serious: seizures, anaphylaxis, Clostridioides difficile infection, positive direct Coombs test.

Interactions. Valproate: carbapenems lower valproate levels by 60 to 100% within 24 hours; avoid the combination. Probenecid raises meropenem levels.

Common prescribing errors. Using it for Pseudomonas or metallo-beta-lactamase producers, shortening the 3-hour infusion, and giving with valproate.

Special groups.

• Pregnancy and breastfeeding: limited data; use only if the benefit outweighs unknown risk.
• Older adults: adjust by kidney function.
• Kidney impairment, creatinine clearance 30 to 49 mL/min: 2 g (1 g/1 g) every 8 hours.
• 15 to 29 mL/min: 1 g (0.5 g/0.5 g) every 12 hours.
• Under 15 mL/min or haemodialysis: 1 g (0.5 g/0.5 g) every 12 hours, given after dialysis on dialysis days.
• Liver impairment: no adjustment.
• Region: availability in East Africa is very limited.

Preparation. Reconstitute each 2 g (1 g/1 g) vial with 20 mL of 0.9% sodium chloride; two vials are needed for a 4 g dose. Dilute in 250 mL of 0.9% sodium chloride and infuse over 3 hours.

Baseline and monitoring. - Baseline: allergy history, medication review (valproate), cultures with carbapenemase testing, creatinine. - During treatment: creatinine twice weekly; liver tests weekly; neurological status. - No therapeutic drug monitoring.

Stop rules. Stop for seizures, anaphylaxis or severe skin reaction.

Referral and escalation. Infectious diseases consultation is needed before use.