This page shows what was measured, who it was measured in, and what that does not settle.
What Meropenem Anhydrous does in the body
Severe hospital infections, including infections in the abdomen, skin and the lining of the brain
Meropenem jams the machinery bacteria use to build their cell wall, and it is shaped so that almost none of the enzymes bacteria use to destroy antibiotics can get a grip on it. An earlier drug of the same type was destroyed by an enzyme in the human kidney; meropenem carries an extra methyl group in exactly the place that stops that happening, so it can be given on its own.
What happened in people
30-day mortality 3.7% on meropenem against 12.3% on piperacillin-tazobactam in 379 randomised patients with ceftriaxone-resistant bloodstream infection
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The recorded finding that sits closest to something a person would notice. Written into the record, not signed off, and it carries no population or interval.
Available at about US$4.67 a vial: what restricts its use is policy, not price
Where it acts
The bacterial periplasm and cell envelope, reached through outer-membrane porins that admit meropenem where other beta-lactams are excluded
Kind of result
The kind of result is not recorded
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · FV9J3JU8B1 · read 2026-08-29
Its recorded molecular formula is C17H25N3O5S•3H2O, weighing 437.52.
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
Where each sentence above came from
No recorded sentence describes the change this makes in a way that stands on its own. The page opens with what it is taken for instead, and the recorded explanation follows below.
Shown as the opening line on this page.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 107 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
All-cause mortality 30 days after randomisation
✓ The study showed what it set out to show
Who was studied
MERINO (NCT02176122, ACTRN12613000532707)
How many people
379
Study design
Phase 4, randomised, parallel-group, non-inferiority, 26 sites in 9 countries
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
3.7% (7 of 191) on meropenem against 12.3% (23 of 187) on piperacillin-tazobactam; risk difference 8.6%, one-sided 97.5% CI upper bound 14.5%, non-inferiority margin 5%, P=.90 for non-inferiority
Repeated elsewhere
Unreplicated
What this does not prove. Meeting one endpoint in one population does not carry to other goals or other people.
The limits of this study, and where it came from
Main limit. A post-hoc central laboratory reanalysis found piperacillin-tazobactam susceptibility testing unreliable: excluding isolates with MIC above 16 mg/L reduced the absolute risk increase from 9% to 5% with an interval crossing zero. The trial answered a clinical question and exposed a diagnostic one.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Intravenous infusion or bolus injection; no oral formulation exists
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
MERINO: piperacillin-tazobactam against meropenem in ceftriaxone-resistant bacteraemia (NCT02176122) · a recorded source, not a stored snapshot
Composite of all-cause mortality and emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28
✗ The study did not show it
Who was studied
MERCY (NCT03452839)
How many people
607
Study design
Phase 4, double-blind, randomised, 31 intensive care units in 4 countries
Compared against
Not recorded for this study
Kind of result
Living longer, or avoiding a major event
What was found
47% against 49%, relative risk 0.96 (95% CI 0.81 to 1.13), P=.60; 90-day mortality 42% in both groups
Repeated elsewhere
Partially Replicated
What this does not prove. A study that did not show an effect does not show that no effect exists anywhere.
The limits of this study, and where it came from
Main limit. None of the four secondary outcomes was significant either. The trial randomised the administration schedule, not the drug, so it says nothing about whether meropenem was the right agent — only that the pharmacokinetic argument for infusing it continuously did not translate into outcome.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Intravenous infusion or bolus injection; no oral formulation exists
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
MERINO: piperacillin-tazobactam against meropenem in ceftriaxone-resistant bacteraemia (NCT02176122) · a recorded source, not a stored snapshot
What we know
RNAWiki holds 2 written-up human studies for this substance, each with the question it asked.
How we know it
Each card names the study, the number of people and what the study set out to measure.
What this does not prove
These summaries were written by a person and have not been signed off as reviewed claims.
Why it matters
A study that failed is as informative as one that worked, and both are here.
What we still do not know
No reviewed claim exists, so no exact population, effect size or interval is published yet.
What it changes in the body◇Read from sources, not yet reviewed
The path through the body
From what a person takes to what changes. A solid line is a step measured in people. A dashed line is a step nobody has measured that way.
Start
Meropenem Anhydrous
What a person takes: Intravenous infusion or bolus injection; no oral formulation exists.
The measurement behind this step
Parenteral only. Unlike imipenem it requires no co-administered dehydropeptidase inhibitor, because the 1-beta-methyl group blocks the renal enzyme that would otherwise degrade it. Predominantly renally cleared. Reconstituted solutions are less stable than most beta-lactams, which constrains how it can be given.
Getting in
Given into a vein, with nothing added to protect it
The first drug of this type was destroyed by an enzyme in the human kidney and had to be given with a second drug to block that enzyme. Meropenem carries one extra methyl group in exactly the right place, and needs no companion.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The 1-beta-methyl substituent sterically blocks hydrolysis by renal dehydropeptidase-1, the brush-border enzyme that degrades imipenem. Imipenem is therefore co-formulated with cilastatin, a dehydropeptidase inhibitor; meropenem is given alone. The same substituent reduces the central nervous system liability that gave the class its seizure reputation.
It enters through a doorway most antibiotics cannot use
Gram-negative bacteria control what gets in through specific protein channels. Meropenem is small and compact enough to use them. Losing one of those doorways is how Pseudomonas becomes resistant without needing any enzyme at all.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Entry into Pseudomonas aeruginosa is largely through the OprD porin. Loss or downregulation of OprD is the commonest mechanism of carbapenem resistance in that organism and confers resistance without any beta-lactamase, which is why a resistant isolate can still test susceptible to every other class.
The side arm on meropenem’s ring points the wrong way for the usual bacterial scissors. Enzymes that shred penicillins and cephalosporins simply cannot complete the reaction on it.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The trans-orientated 6-alpha-hydroxyethyl side chain leaves the acyl-enzyme intermediate in a conformation that resists deacylation by serine beta-lactamases, including extended-spectrum and AmpC enzymes. Only the dedicated carbapenemases — KPC, NDM, VIM, IMP and OXA-48 — hydrolyse it efficiently, and those are the enzymes whose global spread defines the current resistance emergency.
Most beta-lactams block one wall-building enzyme. Meropenem blocks two of the essential ones, which is part of why bacteria find it so hard to escape by a single mutation.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
High affinity for both PBP2, which maintains rod shape, and PBP3, which builds the division septum, produces rapid killing with characteristic morphological change. Binding two independently essential targets means a single point mutation in either does not confer resistance.
Wall repair stops, wall demolition does not, and the bacterium bursts.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
Killing is time-dependent on the fraction of the dosing interval during which free concentration exceeds the minimum inhibitory concentration — the pharmacodynamic rationale that predicted continuous infusion would be superior, and that MERCY tested and did not confirm.
Meropenem works partly because it is used sparingly. Every course adds pressure toward the enzymes that destroy it, and those enzymes are spreading. That cost falls on future patients, and no trial has measured it.
──Measured in people. Written by a person from the study named beside the step. Not signed off as a reviewed claim.
The measurement behind this step
Carbapenemase genes — blaKPC, blaNDM, blaVIM, blaIMP and blaOXA-48 — are carried on mobile genetic elements and spread horizontally between species. MERCY included emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28 in its composite primary outcome and found no difference between infusion strategies; no trial in this file randomised patients to different stewardship policies with resistance as the primary endpoint.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Hospitalised adults and children with severe infection, including infections caused by extended-spectrum beta-lactamase-producing Enterobacterales and by Pseudomonas aeruginosa.
Who is missing from the studies
Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What the label states about particular groups
On pediatric, the label states: “The safety and effectiveness of Meropenem for Injection have been established for pediatric patients 3 months of age and older with complicated skin and skin structure infections and bacterial meningitis, and for pediatric patients of all ages with complicated intra-abdominal infections.”
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
On older people, the label states: “Of the total number of subjects in clinical studies of Meropenem for Injection, approximately 1,100 (30%) were 65 years of age and older, while 400 (11%) were 75 years and older.”
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary There are insufficient human data to establish whether there is a drug-associated risk of major birth defects or miscarriages with meropenem in pregnant women.”
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary Meropenem has been reported to be excreted in human milk.”
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
Where the result stopped carrying
The carbapenem-sparing strategy failed its own definitive trial: piperacillin-tazobactam missed a 5% non-inferiority margin with a mortality difference of 8.6 percentage points
Continuous infusion produced no benefit on any outcome in the 607-patient MERCY trial, and the 7,031-patient BLING III trial missed significance on mortality at P=.08
Routine susceptibility testing for the comparator was shown to be unreliable enough to distort a multinational randomised trial
Carbapenemases that hydrolyse meropenem are carried on mobile elements and have spread globally, which is the ceiling on everything above
This is a scope explorer, not a diagnosis engine.
It shows who was studied so you can see whether people similar to you were included.
RNAWiki cannot tell whether a study fits you. It can show who was in it.
What it would be like to take◇Read from sources, not yet reviewed
Why it might seem to do nothing
A real effect and a noticed effect are different things. These are the recorded reasons the two come apart.
It was studied in different people
The people in the studies were not much like the reader.
On this record: Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
The evidence may simply be wrong
Small early studies often do not hold up.
On this record: RNAWiki has not yet published a reviewed conclusion for this use.
Other reasons RNAWiki checked and found nothing for (11)
It was studied for a different goal
The studies measured something else entirely. Nothing in this record points to this reason.
A different form was studied
The studied form is not the form on the shelf. Nothing in this record points to this reason.
There was nothing to correct
Where a level is already normal, topping it up may change nothing. Nothing in this record points to this reason.
Something else had to happen too
In the studies it was paired with training, a diet or another treatment. Nothing in this record points to this reason.
The change is too small to feel
A real change can still sit below what a person notices. Nothing in this record points to this reason.
Day-to-day swing hides it
Sleep, food, stress and time of day move most numbers more than this would. Nothing in this record points to this reason.
Not enough time yet
The studies ran longer than the person has waited. Nothing in this record points to this reason.
It was not taken as studied
Missed days change the result, and studies count them. Nothing in this record points to this reason.
Something else changed at the same time
Two changes at once cannot be told apart afterwards. Nothing in this record points to this reason.
The product may not be what it says
Contents of a sold product are not always what the label states. Nothing in this record points to this reason.
No recorded reason
RNAWiki has nothing stored that would explain it. Nothing in this record points to this reason.
None of these is a reason to take more. Taking more is not a step this page ever suggests.
What it would be like to take◇Read from sources, not yet reviewed
What taking it involves
The recorded facts about getting hold of it and using it. Nothing here is a suggestion about what you should do.
How it is supplied
Given by a clinician
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Read from the recorded approval status.
No source is stored against this line.
Form and route
Intravenous infusion or bolus injection; no oral formulation exists
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
Parenteral only. Unlike imipenem it requires no co-administered dehydropeptidase inhibitor, because the 1-beta-methyl group blocks the renal enzyme that would otherwise degrade it. Predominantly renally cleared. Reconstituted solutions are less stable than most beta-lactams, which constrains how it can be given.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on how this is sold and what that means for what is in the pack.
No source is stored against this line.
Where it is registered
Regulatory records are listed in the technical disclosure at the foot of this page.
# Counted from records
Where this came from
A count of rows RNAWiki holds. It describes our records, not your body.
Register entries are stored per jurisdiction and shown with their dates.
No source is stored against this line.
Why people stop
Not recorded.
∅ Nothing recorded
Where this came from
RNAWiki holds nothing here and says so rather than guessing.
No record of why people stopped taking it is stored for this substance.
No source is stored against this line.
What it would be like to take◇Read from sources, not yet reviewed
What can go wrong
Sorted by where each line came from. A regulator's label and a report somebody sent in are not the same kind of fact.
·Worth asking a clinician aboutWritten into the record from the studies named on this page
Better tolerated than its class reputation suggests: in 607 critically ill patients treated for a median 11 days, no seizures or allergic reactions were attributed to the drug. The label nonetheless warns of seizures and other central nervous system events, of serious and occasionally fatal anaphylaxis, and of severe cutaneous adverse reactions including Stevens-Johnson syndrome, toxic epidermal necrolysis, DRESS, erythema multiforme and acute generalised exanthematous pustulosis. Thrombocytopenia has been observed in renal dysfunction. The interaction that most often matters is with valproic acid or divalproex: meropenem lowers valproate concentrations, potentially below the range that controls seizures, and the label advises considering a non-carbapenem alternative in patients whose epilepsy is controlled on valproate.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
Over a long time. No completed tested study window is recorded, so long-term effects are not established by the registry record.
Groups the studies covered thinly. Which groups were under-represented in the studies has not been recorded for this substance. Pregnancy, breastfeeding, children, older adults, and people with liver or kidney conditions are commonly excluded from trials; nothing here says whether they were.
What is missing or unclear◇Read from sources, not yet reviewed
Does the exact form matter?
Evidence belongs to the exact thing that was tested. A different salt, a different mixture or a different preparation is a different question.
The form that was studied
Intravenous infusion or bolus injection; no oral formulation exists
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form used in the studies cited on this page.
No source is stored against this line.
What is sold
Unlike imipenem it requires no co-administered dehydropeptidase inhibitor, because the 1-beta-methyl group blocks the renal enzyme that would otherwise degrade it. Predominantly renally cleared. Reconstituted solutions are less stable than most beta-lactams, which constrains how it can be given.
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
Recorded notes on which forms are sold and how they compare.
No source is stored against this line.
What is recorded as being sold
54 products list this as an active ingredient in the United States drug directory. 53 of them contain it and nothing else.
FDA National Drug Code directory · 72572-415 · read 2026-08-29
They are sold as injection, injection, powder, for solution, injection, solution and powder, taken intravenous.
FDA National Drug Code directory · 72572-415 · read 2026-08-29
The regulator's established pharmacologic class for it is carbapenems [cs] and penem antibacterial [epc].
FDA National Drug Code directory · 72572-415 · read 2026-08-29
26 published labels name it as an active ingredient. 25 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-29
Meropenem is intravenous at 3 DOSAGE FORMS AND STRENGTHS Single dose clear glass vials of Meropenem for Injection, USP containing 500 mg or 1 gram (as the trihydrate blended with anhydrous sodium carbonate for re-constitution) of sterile meropenem…, recorded as fda label in effect 2025-07-16 in the United States.
US prescribing information · bf1d3433-9e3f-40a0-8bff-c8ceaa8bab7c · read 2026-08-30
Evidence carries across two names for one substance. It does not carry across a salt, a mirror form or a mixture.
What it would be like to take◇Read from sources, not yet reviewed
What you could measure
This one is decided with a clinician, so this section holds questions to ask rather than a plan to run.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Meropenem Anhydrous studied people like me?
What was measured, and for how long?
Was the result a laboratory value or a health outcome?
What would we watch for, and when would we stop?
Tracking can show whether something changed for you. It cannot show what caused it.
RNAWiki records evidence. It does not say whether this substance is right for you.
What is missing or unclear◇Read from sources, not yet reviewed
Claims that go past the evidence
Things said about this substance that sound reasonable, and the exact step that is missing between the evidence and the claim.
✗Goes past the evidence
That restricting meropenem preserves its effectiveness — the premise of stewardship, never tested with resistance as a randomised primary endpoint
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That keeping free drug concentrations continuously above the minimum inhibitory concentration improves outcome — null in MERCY, P=.08 in the 7,031-patient BLING III trial, and supported at high certainty only by Bayesian pooling of 18 trials
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That MERINO measured a clean drug-versus-drug difference, when a substantial part of it was comparator given to organisms that were not truly susceptible
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
✗Goes past the evidence
That a single 391-patient trial settles definitive therapy for all ESBL bloodstream infections; MERINO has not been independently replicated
Why it sounds right. It follows from something real on this page: a body step, an animal result or a related finding.
The missing step. Nobody measured this in people for this use, or the study that did measure it did not show it.
What would change this
A study in people, for this exact use, measuring this exact thing, that a reviewer signs off.
RNAWiki has not yet published a reviewed conclusion for this use.
What is missing or unclear◇Read from sources, not yet reviewed
What nobody knows yet
Open questions, each with why it is open and what would close it.
Missing populations
Which groups were under-represented in the studies has not been recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing long-term data
No completed tested study window is recorded.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
No reviewed conclusion
RNAWiki has not yet published a reviewed conclusion for this use.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Missing interaction studies
No interaction was found in the registers checked. Not finding one is not the same as showing there is none.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Formulation uncertainty
Several salts, forms or products of Meropenem Anhydrous are recorded. Results from one form may not transfer to another.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
Mechanism not reviewed
No reviewed mechanism story exists for this substance.
Why it matters. Recorded by the evidence model as a gap on this record.
What would answer it
A study that measures it, and a reviewer to sign it off.
Last checked 2026-09-04. Searched: The sources listed in the receipts at the foot of this page.
What happened in people◇Read from sources, not yet reviewed
Check any of this yourself
Every line above traced back to the study it came from. This is the technical layer, and the vocabulary changes here.
Every line above can be traced to the study named beside it. Follow the link and read it.
MERINO: 3.7% mortality on meropenem against 12.3% on the carbapenem-sparing option
In plain words
A trial across nine countries set out to show that a cheaper, older antibiotic could replace meropenem in serious bloodstream infections, so that meropenem could be saved for later. It found that three times as many patients died on the alternative.
What was measured
All-cause mortality 30 days after randomisation, non-inferiority design with a 5% margin
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
MERINO enrolled at 26 sites in 9 countries. Of 1,646 patients screened, 391 were randomised: adults with at least one blood culture growing Escherichia coli or Klebsiella non-susceptible to ceftriaxone but susceptible to piperacillin-tazobactam. In the primary analysis population of 379 patients (mean age 66.5, 47.8% women), 30-day all-cause mortality was 23 of 187 (12.3%) with piperacillin-tazobactam against 7 of 191 (3.7%) with meropenem — a risk difference of 8.6% with a one-sided 97.5% confidence bound of 14.5%, against a pre-specified non-inferiority margin of 5%. P for non-inferiority was .90. The effect was consistent in the per-protocol population. Non-fatal serious adverse events were 2.7% and 1.6%.
Written into the record, not signed off as a reviewed claim
Half the MERINO effect was a susceptibility-testing artefact — and the answer held
In plain words
When the blood isolates were retested in a single central laboratory, some had been wrongly called susceptible to the comparator drug. Correcting that cut the mortality gap roughly in half. It did not close it, and the conclusion did not change.
What was measured
That MERINO measured a pure drug-versus-drug difference — a substantial part of it was the comparator being given to patients whose organism was not actually susceptible, which is a finding about diagnostic reliability as much as about pharmacology
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Central broth microdilution and whole genome sequencing were performed on 320 of 379 isolates. Piperacillin-tazobactam susceptibility was 94% and meropenem susceptibility 100%. The piperacillin-tazobactam non-susceptible breakpoint of MIC above 16 mg/L best predicted 30-day mortality after adjustment for confounders (odds ratio 14.9, 95% CI 2.8 to 87.2). The absolute risk increase for piperacillin-tazobactam against meropenem was 9% (95% CI 3 to 15%) in the original primary analysis population and 8% (95% CI 2 to 15%) in the microbiologically assessable population, falling to 5% (95% CI -1 to 10%) once strains with MIC above 16 mg/L were excluded. Isolates co-harbouring an extended-spectrum beta-lactamase and OXA-1 had elevated MICs and the highest risk increase at 14% (95% CI 2 to 28%). The authors concluded that poor reliability of piperacillin-tazobactam susceptibility testing, and the high prevalence of OXA-1 alongside ESBLs, mean meropenem remains the preferred choice.
Written into the record, not signed off as a reviewed claim
Continuous infusion: the strongest pharmacological prediction in the field, and null
In plain words
Beta-lactams kill best when the drug level stays above a threshold, so giving meropenem as a slow continuous drip rather than short doses should work better. In 607 critically ill patients it made no difference to anything. Two larger studies since have pulled in the other direction without settling it.
What was measured
Composite of 28-day all-cause mortality and emergence of pandrug-resistant or extensively drug-resistant bacteria
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
MERCY was a double-blind randomised trial in 607 critically ill patients with sepsis or septic shock across 31 intensive care units in Croatia, Italy, Kazakhstan and Russia, receiving an equal daily dose of meropenem by continuous (n=303) or intermittent (n=304) administration. Sixty-one percent had septic shock; median time from admission to randomisation was 9 days and median therapy duration 11 days. The composite primary outcome of all-cause mortality plus emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28 occurred in 142 (47%) against 149 (49%), relative risk 0.96 (95% CI 0.81 to 1.13), P=.60. None of the four secondary outcomes was statistically significant. Mortality at 90 days was 42% in both groups — 127 of 303 against 127 of 304. The question did not end there: BLING III later randomised 7,031 critically ill adults to continuous or intermittent piperacillin-tazobactam or meropenem and found 90-day mortality of 24.9% against 26.8%, odds ratio 0.91 (95% CI 0.81 to 1.01), P=.08, with higher clinical cure on continuous infusion; a Bayesian pooling of 18 trials in 9,108 patients then estimated a mortality risk ratio of 0.86 (95% credible interval 0.72 to 0.98) at high certainty. MERCY is null, the largest trial missed significance, and the pooled estimate favours prolonged infusion.
Written into the record, not signed off as a reviewed claim
No seizures attributed to the drug in 607 critically ill patients over a median 11 days
In plain words
Carbapenems have a reputation for causing seizures, earned by the first drug in the class. In a trial giving meropenem to six hundred severely ill patients for a median of eleven days, no seizures or allergic reactions were attributed to it.
What was measured
Protocol-recorded seizures and allergic reactions attributed to study drug in a 607-patient randomised trial
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
MERCY recorded seizures, allergic reactions and mortality as adverse events by protocol. In 607 patients with sepsis or septic shock, median meropenem duration 11 days (IQR 6 to 17), no adverse events of seizures or allergic reactions related to the study drug were reported. This is consistent with the structural difference: the 1-beta-methyl group that confers dehydropeptidase-1 stability also reduces the central nervous system liability that characterised imipenem. The label nonetheless carries a seizure warning, records severe cutaneous adverse reactions including Stevens-Johnson syndrome and toxic epidermal necrolysis, and warns that meropenem lowers valproic acid concentrations enough to cause breakthrough seizures.
Written into the record, not signed off as a reviewed claim
Every trial measures this patient; none measures the next one
In plain words
The entire reason meropenem is rationed is that using it breeds bacteria that resist it. Not one of the trials on this page measured that. The case for restraint rests on mechanism and on population surveillance, not on any randomised comparison.
What was measured
That restricting meropenem preserves its future effectiveness — the entire premise of carbapenem stewardship, mechanistically compelling, ecologically supported, and not measured as a randomised endpoint by any trial on this page
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
MERINO’s stated purpose was to identify a carbapenem-sparing option, precisely because treating ESBL producers with carbapenems is expected to select for carbapenem resistance. The trial measured 30-day mortality and did not measure subsequent carbapenem-resistant colonisation or infection in either arm, in participants or in their units. MERCY came closest of any trial in this file: it made emergence of pandrug-resistant or extensively drug-resistant bacteria at day 28 part of its composite primary outcome — and found no difference between infusion strategies, which answers a question about how to give the drug rather than whether to. The proposition that restricting meropenem preserves its usefulness is supported by mechanism, by ecological surveillance and by the observed spread of KPC, NDM, VIM and OXA-48 enzymes, and it has never been tested by randomising patients or units to different stewardship policies with resistance as the primary endpoint.
This order is fixed in code and does not count clicks or time on the page.
What is not here
7 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A carbapenem with a methyl group that blocks the human kidney enzyme which destroyed its predecessor, and a ring that resists almost every bacterial beta-lactamase — in the MERINO trial, 30-day mortality was 3.7% on meropenem against 12.3% on piperacillin-tazobactam in ceftriaxone-resistant bloodstream infection, and in MERCY, the continuous infusion that pharmacology predicted would work better made no difference at all in 607 patients with sepsis.
Recorded evidence blocks (10)
Q1
On the Meropenem Anhydrous label: indicated for what?
"Meropenem for Injection is a penem antibacterial indicated for the treatment of: • Complicated skin and skin structure infections (adult patients and pediatric patients 3 months of age and older only). ( 1.1 ) • Complicated intra-abdominal infections (adult and pediatric patients).": indications and usage on Meropenem Anhydrous's label. DailyMed label · 8a2a545e-b336-416a-be73-9e0a7ccf6177 · 2026-08-26
Q2
126 registered trials of Meropenem Anhydrous — at which phases?
Registered studies posting no result
100 of 126
126 registered studies of Meropenem Anhydrous: 36 phase4, 33 phase3, 24 phase2, 17 na or unstated, 16 phase1, 8 na, 2 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
346 with a PubMed record
Show the evidence
phase4
36
phase3
33
phase2
24
na or unstated
17
phase1
16
na
8
8 more recorded rows
early phase1
2
completed
70
unknown
25
recruiting
10
terminated
10
withdrawn
6
not yet recruiting
4
suspended
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
16 of Meropenem Anhydrous's trials stopped: safety, accrual/recruitment, funding/business, other?
safety (1), accrual/recruitment (4), funding/business (4) and other (7): Meropenem Anhydrous's stop wording, clustered. CLINICALTRIALS_SNAPSHOT · 2026-09-01
"difficulties by enrolling patients fundings consumed, no staff could be recruited and payed to continue enrolling patients,"; 16 of 126 registered studies
Show the evidence
Trial
NCT00435305
terminated; "difficulties by enrolling patients fundings consumed, no staff could be recruited and payed to continue enrolling patients,"
NCT01110382
terminated; "Trial terminated early per business decision"
NCT01381562
terminated; "Microbiological findings of resistance on therapy in patients with complicated urinary tract infection"
NCT02099240
terminated; "Not enough patient enrollment and lack of staffing"
NCT02168816
terminated; "The study was stopped for feasibility (i.e., low recruitment)"
NCT02176122
terminated; "Secondary to third interim analysis by the study DSMB."
10 further recorded trials
NCT02732327
terminated; "No longer aligned with the revised clinical development plan and commercial strategy"
NCT02840136
terminated; "Lack of staff"
NCT03036826
withdrawn; "due to organisational changes"
NCT03108690
withdrawn; "Logistics"
NCT03891433
suspended; "Low admission of patients with the condition to the hospital because it is a reference center for care of the SARS-CoV-2 pandemic"
NCT04238390
withdrawn; "The decision to withdraw the study was made due to delayed logistics of the supply chain of ceftolozane-tazobactam along with the immense complexities of conducting clinical research felt because of the COVID-19 pandemic."
NCT04876430
terminated; "Very low frequency of recruitment"
NCT05355350
withdrawn; "No eligible patients"
NCT05784844
withdrawn; "Study was never initiated or activated - Reason was lack of funding"
NCT06168734
withdrawn; "Study suspended"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Meropenem Anhydrous used MEROPENEM 2 grams TID — over how long?
Human studies of Meropenem Anhydrous used "MEROPENEM 2 grams TID". ClinicalTrials.gov · 2026-09-01
5 recorded entries; human; also "MEROPENEM 1 gram TID", "MEROPENEM 3 grams QD", "Meropenem 1000 mg"
Show the evidence
human
NCT03174184
MEROPENEM 2 grams TID
NCT03174184
MEROPENEM 1 gram TID
NCT03174184
MEROPENEM 3 grams QD
NCT04233996
Meropenem 1000 mg
NCT05578586
Meropenem 2000 mg
recorded 2026-09-01 · last checked 2026-09-04
Q5
Meropenem Anhydrous's half-life is 2 hours — which schedules were studied?
2 hours, the half-life Meropenem Anhydrous's label states: "1 (2 hours) 5.3 to 6.9 Fascia 1 9 8.8 1.5 to 20 Heart valves 1 7 9.7 6.4 to 12.1 Myocardium 1 10 15.5 5.2 to 25.5 CSF (inflamed) 20 mg/kg in pediatric patients of age 5 months to 8 years 40 mg/kg in pediatric patients of age 1 month to 15 years 8 5 1.1 (2 hours) 3.3 (3 hours) 0.2 to 2.8 0.9 to 6.5 CSF (uninflamed) 1 4…" DailyMed label · 8a2a545e-b336-416a-be73-9e0a7ccf6177 · 2026-08-26
Show the evidence
half lifepharmacokinetics
2 hours; 1 (2 hours) 5.3 to 6.9 Fascia 1 9 8.8 1.5 to 20 Heart valves 1 7 9.7 6.4 to 12.1 Myocardium 1 10 15.5 5.2 to 25.5 CSF (inflamed) 20 mg/kg in pediatric patients of age 5 months to 8 years 40 mg/kg in pediatric patients of age 1 month to 15 years 8 5 1.1 (2 hours) 3.3 (3 hours) 0.2 to 2.8 0.9 to 6.5 CSF (uninflamed) 1 4 0.2 (2 hours) 0.1 to 0.3 at 1 hour unless otherwise noted obtained from blister…
metabolismpharmacokinetics
Metabolism There is one metabolite of meropenem that is microbiologically inactive.
recorded 2026-08-26 · last checked 2026-09-04
Q6
Which running trial of Meropenem Anhydrous could settle lifespan?
NCT06841731 measures The all-cause mortality rate at Day 14., reading out 2026-02.
4 open trials; n 100; "A Trial of HRS-8427 in the Treatment of Adults With Bacterial Pneumonia"
Show the evidence
Trial
NCT06841731
"A Trial of HRS-8427 in the Treatment of Adults With Bacterial Pneumonia"; n 100; "The all-cause mortality rate at Day 14."; 2026-02
NCT05922124
"Cefiderocol and Ampicillin-sulbactam vs. Colistin +/- Meropenem for Carbapenem Resistant A. Baumannii"; n 734; "All cause mortality"; 2026-09
NCT03671967
"PipEracillin Tazobactam Versus mERoPENem for Treatment of Bloodstream Infections Caused by Cephalosporin-resistant Enterobacteriaceae (PETERPEN)"; n 1084; "All-cause mortality"; 2027-04-01
NCT06184659
"Empirical Meropenem Versus Piperacillin/Tazobactam for Adult Patients With Sepsis"; n 5800; "All-cause mortality"; 2029-03-30
Q7
Which 44 trials of Meropenem Anhydrous posted no result?
Posted no result
44 of 44 completed trials
Registrations
NCT00619710, NCT00061438, NCT02615041, NCT00318552, NCT00318994 and NCT00410527, and 38 more
Completion dates
oldest 2004-04; newest 2024-01-05
Show the evidence
Trial
NCT00619710
2004-04
NCT00061438
2004-12
NCT02615041
2005-01
NCT00318552
2006-06
NCT00318994
2007-05
NCT00410527
2007-05-22
14 further recorded trials
NCT00462878
2009-04
NCT02506686
2009-12
NCT00891423
2010-01
NCT00534287
2010-06
NCT01572558
2012-10
NCT02212392
2013-12
NCT02213796
2013-12
NCT01551394
2014-12
NCT01554124
2014-12
NCT02349841
2014-12
NCT02503761
2015-06
NCT01292031
2015-12
NCT01732250
2017-02-28
NCT02972255
2017-03-24
Q8
At the median, Meropenem Anhydrous's trials enrolled 103 people — anything larger?
Median enrolment
103
Largest enrolment
5800
Registered trials counted
126
Q9
What do 1825 spontaneous reports say about Meropenem Anhydrous — and not say?
These are reports people sent to a regulator. They do not show the medicine caused the reaction. Nobody counted how many people took the medicine and reported nothing. The same event can be reported more than once, and many reports are incomplete. News coverage, lawsuits and new warnings change how often people report. A count is not a rate and not a risk.
Meropenem Anhydrous appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 1825 reaction mentions were counted: pyrexia 328; drug reaction with eosinophilia and systemic symptoms 265; thrombocytopenia 202; drug interaction 169. FAERS via Open Targets · CHEMBL127 · 2026-06-24
Show the evidence
pyrexia
328
drug reaction with eosinophilia and systemic symptoms
265
thrombocytopenia
202
drug interaction
169
acute kidney injury
159
drug resistance
158
4 more recorded rows
rash maculo-papular
145
eosinophilia
139
pancytopenia
139
sepsis
121
recorded 2026-06-24 · last checked 2026-09-04
Q10
Which 10 reactions does Meropenem Anhydrous's label not list?
acute kidney injury, drug interaction and drug reaction with eosinophilia and systemic symptoms and 7 more reported for Meropenem Anhydrous, absent from its label. FAERS via Open Targets · CHEMBL127 · 2026-06-24
2 label terms; 10 reported and unlisted; 8a2a545e-b336-416a-be73-9e0a7ccf6177
Show the evidence
acute kidney injury
count not stated
drug interaction
count not stated
drug reaction with eosinophilia and systemic symptoms
count not stated
drug resistance
count not stated
eosinophilia
count not stated
pancytopenia
count not stated
4 more recorded rows
pyrexia
count not stated
rash maculo-papular
count not stated
sepsis
count not stated
thrombocytopenia
count not stated
recorded 2026-06-24 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ChEMBL 37 — CC BY-SA 3.0 Unported · ChEMBL ATC CC BY-SA · ClinicalTrials.gov — US Government work · Open Targets 26.06 — CC0 · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
✗ required summary fields resolved: 4 required field(s) not terminal: Why people use it, Best-supported result, Biggest unanswered question, Human evidence
✓ public claims reviewed: 0 reviewed claim(s); drafts are never rendered
✓ source coverage passed: 6 source rows
✓ no critical contamination: no quarantine open
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
This is a record of evidence. It is not medical advice, and it does not say this substance suits you. Nothing here says any substance on RNAWiki is appropriate for a child.