Cilastatin

證據等級: L5

預測適應症: 10 個

Cilastatin: From Carbapenem Adjunct to Staphylococcus Aureus Infection

One-Sentence Summary

Cilastatin is a renal dehydropeptidase-1 (DHP-1) inhibitor with no independent antimicrobial activity; it is always co-administered with imipenem as the fixed combination imipenem/cilastatin to prevent renal tubular degradation of imipenem and maintain effective systemic drug concentrations. The TxGNN model predicts that the imipenem/cilastatin combination may be effective for Staphylococcus aureus infection, with 3 clinical trials and 20 publications currently providing supporting context. Evidence quality, however, is predominantly observational and historically dated, placing this prediction at the research-question stage rather than ready for direct clinical deployment.

Quick Overview

Item	Content
Original Indication	No standalone approved indication; cilastatin functions solely as a DHP-1 inhibitor co-drug within the imipenem/cilastatin combination
Predicted New Indication	Staphylococcus aureus infection
TxGNN Prediction Score	99.94%
Evidence Level	L3
Saudi Arabia Market Status	Not marketed
Number of Authorizations	0
Recommended Decision	Hold

Why is This Prediction Reasonable?

Cilastatin itself has no antimicrobial mechanism — it competitively inhibits renal DHP-1, the enzyme responsible for degrading imipenem in proximal renal tubules. Without cilastatin, imipenem would be rapidly hydrolysed in the kidney, producing nephrotoxic metabolites and failing to achieve therapeutic systemic concentrations. All clinical evidence for "cilastatin" therefore belongs entirely to the imipenem/cilastatin combination, and this repurposing assessment must be understood in that context.

Imipenem, the active partner, binds penicillin-binding proteins (PBPs) and inhibits bacterial cell wall synthesis. It has documented in vitro and in vivo activity against methicillin-susceptible Staphylococcus aureus (MSSA), and early clinical studies (1986–1994) confirmed clinical cure in soft tissue, bacteraemic, and skeletal MSSA infections. The mechanistic bridge is thus well-founded for MSSA. For methicillin-resistant S. aureus (MRSA), however, the picture is considerably more complex: MRSA expresses PBP2a (encoded by mecA), which confers intrinsic resistance to all β-lactams including carbapenems. Imipenem is bacteriostatic rather than bactericidal against MRSA at clinically achievable concentrations, substantially limiting monotherapy utility.

The residual interest in imipenem/cilastatin for MRSA stems from observed in vitro and in vivo synergy with partner agents — particularly arbekacin, fosfomycin, cefotiam, and vancomycin — where adding imipenem reduces MICs and improves killing kinetics. A 2020 case commentary in Antimicrobial Agents and Chemotherapy described successful salvage therapy with imipenem/cilastatin + fosfomycin for a refractory MRSA bacteraemic case where both vancomycin and daptomycin had failed, illustrating the niche role of this combination in individualised rescue situations. TxGNN likely captures this relationship through knowledge-graph edges linking imipenem/cilastatin to S. aureus-associated infection nodes, but the underlying evidence does not yet support a defined, registrable indication.

Clinical Trial Evidence

Trial Number	Phase	Status	Enrollment	Key Findings
NCT03583333	Phase 3	Completed	274	IMI/cilastatin/relebactam vs piperacillin/tazobactam in HABP/VABP adults; imipenem/cilastatin serves as backbone active comparator, confirming its gold-standard role in serious Gram-positive and Gram-negative infections — indirect support for SA pneumonia coverage
NCT00707239	Phase 2	Terminated	108	Two tigecycline doses vs imipenem/cilastatin for hospital-acquired pneumonia (≥70% VAP); terminated early and results are limited, but trial design validates imipenem/cilastatin as comparator for serious bacterial pneumonia including SA aetiology
NCT01356472	Phase 4	Unknown	60	Linezolid alone vs linezolid + carbapenem in MRSA VAP patients; most directly relevant to SA — investigates whether adding a carbapenem to linezolid improves outcomes in MRSA pneumonia; status unknown reduces confidence

Literature Evidence

PMID	Year	Type	Journal	Key Findings
3460521	1986	Clinical Study (non-RCT)	Antimicrob Agents Chemother	Imipenem-cilastatin in 23 patients (11 MRSA, 12 MSSA); soft tissue, endovascular, and skeletal infections; MIC90 6.25 μg/mL for MSSA — foundational clinical evidence, now decades old
33020155	2020	Case Report	Antimicrob Agents Chemother	Commentary on imipenem/cilastatin + fosfomycin for refractory MRSA bacteraemia after vancomycin and daptomycin failure; argues for individualised combination salvage strategies
8072190	1994	Clinical Study (non-RCT)	Jpn J Antibiotics	Arbekacin + imipenem/cilastatin combination against clinical MRSA isolates; MICs in combination significantly lower than either agent alone; clinical benefit in MRSA infections documented
10588305	1999	Preclinical	J Antimicrob Chemother	Vancomycin + imipenem synergy against MRSA in vitro (34/36 isolates showed synergy or additivity) and in neutropenic mouse thigh model; supports dual-agent rationale
3378959	1988	Animal Study	J Antimicrob Chemother	Imipenem-cilastatin vs vancomycin in rabbit MRSA aortic valve endocarditis; imipenem bacteriostatic in vitro (MBC90 32 mg/L) but showed favourable in vivo efficacy by certain criteria — important nuance for MRSA endocarditis
8514648	1993	Preclinical	J Antimicrob Chemother	Imipenem/cilastatin + cefotiam synergy in mouse MRSA bacteraemia model (ratios 1:5–1:160); effective against both β-lactamase-producing and non-producing MRSA; mechanism explored via in vitro PK system
22196394	2012	Review	Int J Antimicrob Agents	Comprehensive review of MRSA virulence, key clinical trials, and resistance implications; places carbapenem-based combinations as investigational options for severe refractory MRSA
36804370	2023	Review	Int J Antimicrob Agents	Off-label antibiotic use vs formal recommendations for MDR bacteria including MRSA; discusses carbapenem combinations as an option when licensed anti-MRSA agents are unavailable or have failed
18649613	2008	Review	Am Fam Physician	Diabetic foot infection review; identifies S. aureus and β-haemolytic streptococci as dominant pathogens in mild-moderate untreated infections; severe polymicrobial cases may require broad-spectrum coverage including carbapenems
1771308	1991	Review	Semin Respir Infect	Antibiotic therapy of pleural empyema; notes SA as a relevant nosocomial pathogen; polymicrobial aetiology supports broad-spectrum carbapenem coverage in severe cases

Saudi Arabia Market Information

Cilastatin (as imipenem/cilastatin combination) is not currently marketed in Saudi Arabia. There are no SFDA-registered products and no recorded licenses. Any future use would require a full regulatory submission pathway.

Safety Considerations

Formal safety data (key warnings, contraindications, drug–drug interactions) is not available in this evidence pack.

Please refer to the package insert for safety information.

Notable adverse events identified in the literature:

Leukocytoclastic vasculitis (PMID 9158321, 1997): First reported case of imipenem/cilastatin-induced vasculitic skin reaction presenting as maculopapular rash progressing to leukocytoclastic pattern.

Acute eosinophilic pneumonia (PMID 26944380, 2016): Drug-induced eosinophilic pneumonia one day after initiation, presenting with fever, acute hypoxic respiratory distress, and diffuse ground-glass opacities on CT; resolved on drug withdrawal.

Conclusion and Next Steps

Decision: Hold

Rationale: Evidence for imipenem/cilastatin in Staphylococcus aureus infection is confined to small non-RCT clinical studies from 1986–1994, animal models, in vitro synergy experiments, and isolated case reports — none of which constitute a contemporary controlled trial targeting SA as the primary indication. Critically, MRSA's intrinsic PBP2a-mediated resistance limits monotherapy applicability, and combination synergy data, while intriguing, has not been validated in prospective trials.

To proceed, the following is needed:

MSSA vs. MRSA stratification: Clearly separate the two scenarios — MSSA infections represent a mechanistically sound target; MRSA requires combination strategy and should be evaluated as a distinct research question
Modern PK/PD analysis: Confirm that imipenem achieves >40–50% T>MIC for MSSA isolates at approved dosing regimens in the target patient populations
Phase 2 RCT for MSSA bacteraemia: Compare imipenem/cilastatin to anti-staphylococcal penicillins (nafcillin/flucloxacillin) or cefazolin, the current first-line agents for MSSA bacteraemia
MRSA combination validation: A prospective pilot study (Phase 2) testing imipenem/cilastatin + fosfomycin in documented MRSA bacteraemia refractory to vancomycin/daptomycin
SFDA regulatory pathway: Assess registration requirements for imipenem/cilastatin in Saudi Arabia before any clinical programme is initiated
Full safety profile: Obtain complete package insert data including contraindications, black-box warnings, and drug interaction profile (currently all are data gaps)
Disclaimer

This content is for research purposes only and does not constitute medical advice. Clinical validation is required before any clinical application.