This page shows what was measured, who it was measured in, and what that does not settle.
What Lorcaserin does in the body
A twice-daily weight-loss tablet
Certain neurons in the appetite centre of the brain make you feel full. Serotonin switches them on through one particular receptor, and lorcaserin was engineered to hit that receptor and avoid its close relatives — especially the one on heart valves that ended fenfluramine. It worked: appetite fell, weight came off, and the valves were fine. The reason it is gone is a small excess of cancers found in the long safety trial, and that imbalance has never been resolved either way.
What happened in people
At least 5 per cent weight loss at one year in 38.7 per cent versus 17.4 per cent, odds ratio 3.01 (95% CI 2.74 to 3.30), in 12,000 patients
✎ 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.
The 5-HT2C over 5-HT2B selectivity strategy that this drug validated remains sound; it was simply not sufficient
Where it acts
Hypothalamic arcuate nucleus; 5-HT2C receptors on pro-opiomelanocortin neurons, with brainstem GLP-1 neurons also implicated
Kind of result
A number that stands in for health
Supervision
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · 637E494O0Z · read 2026-08-29
Its recorded molecular formula is C11H14ClN, weighing 195.69.
PubChem record · 11658860 · read 2026-08-29
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 122 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.
Stand-in result
A stand-in result is a number measured because the real result takes too long.
A picture of it, and where the picture fails
It is like judging a journey by the speedometer rather than by arriving.
Where that stops being true. Speed does predict arrival. Many stand-in results do not predict the real one.
What people get wrong. A stand-in result is often reported as the result itself.
A surrogate endpoint substituted for a clinical endpoint, valid only where the substitution has been shown to hold.
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 was measured, goal by goal
One row for each goal a registered study measured something for. One column for each kind of thing that could be measured.
Registered studies list 13 outcome measures that RNAWiki could read. A registered study says what someone planned to measure. It does not say what they found. 0 of the matched studies tested this substance, and 0 posted a result.
There is no single score. A strong test result and a weak life result are different facts.
Goals down the side, kinds of measurement across the top. Each cell says what kind of thing was registered, not what was found.
Goal
Life outcome
What a body can do
How a person feels
A test result
A step in the body
Harms
How long
Who was studied
Body weight
∅Nothing in the sources checkedNo registered study lists a life outcome for this goal.
∅Nothing in the sources checkedNo registered study lists a performance measure for this goal.
∅Nothing in the sources checkedNo registered study lists a symptom measure for this goal.
△Only a number moved3 registered test measure.
∅Nothing in the sources checkedNo registered study lists a body-step measure for this goal.
—Not recordedHarms were not a registered measure for this goal.
—Not recordedNo finished study window is recorded.
…Waiting for a reviewerWho was studied is listed further down the page.
Which registered measures put each goal on this table
Body weight
body weight; weight loss; post cessation weight change
Sorted by fixed word lists, version v1. A name the rules do not recognise stays unsorted rather than moving to the nearest column.
What each mark on this table means
∅ Nothing in the sources checked
No registered study lists a life outcome for this goal.
△ Only a number moved
3 registered test measure.
— Not recorded
Harms were not a registered measure for this goal.
… Waiting for a reviewer
Who was studied is listed further down the page.
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.
Major cardiovascular events — cardiovascular death, myocardial infarction or stroke — assessed against a non-inferiority boundary of 1.4, over a median 3.3 years
2.0 versus 2.1 per cent per year, hazard ratio 0.99 (95% CI 0.85 to 1.14), P < 0.001 for non-inferiority; extended MACE 4.1 versus 4.2 per cent per year, hazard ratio 0.97 (0.87 to 1.07), P = 0.55
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. Serious hypoglycaemia was more frequent on lorcaserin (13 versus 4, P = 0.04). Cancer was not a prespecified endpoint, and the imbalance that ended the drug emerged from follow-up of this trial.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
Weight loss at one year and maintenance of weight loss at two years, with serial echocardiography for FDA-defined valvulopathy
✓ The study showed what it set out to show
Who was studied
NCT00395135
How many people
3182
Study design
Phase 3 (BLOOM)
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
47.5 per cent versus 20.3 per cent lost at least 5 per cent of body weight at one year (P < 0.001); mean loss 5.8 ± 0.2 kg versus 2.2 ± 0.1 kg; no increase in valvulopathy in 2,472 patients at one year and 1,127 at two years
Repeated elsewhere
Replicated
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. Retention was 55.4 per cent on lorcaserin and 45.1 per cent on placebo at one year, so the one-year comparison rests on a substantially incomplete cohort in both arms.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Incidence of new cancer with lorcaserin against other interventions or no treatment
✗ The study did not show it
Who was studied
Systematic review and meta-analysis of cancer incidence (de Andrade Mesquita et al.)
How many people
21299
Study design
Systematic review and meta-analysis of randomised trials
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
476 cases in 10,342 lorcaserin subjects against 438 in 9,429 on placebo; relative risk 1.08 (95% CI 0.96 to 1.23)
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. The pooled estimate is heavily influenced by CAMELLIA-TIMI 61, in which lung and pancreatic but not colon cancer were more frequent. Risk of bias was low and evidence quality moderate.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily
Interval reported. 95% CI 0
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 3 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 happened in people◇Read from sources, not yet reviewed
How close this is to real life
The top step is something a person would feel or care about. The bottom is a guess from software. Filled steps are where evidence exists for this substance.
□Living longer, or avoiding a major eventNo evidence recorded. Death, a heart attack, a stroke, a hospital stay.No registered study measures this.
□What a body can do day to dayNo evidence recorded. Walking, dressing, breathing, recovering.No registered study measures this.
□Measured performanceNo evidence recorded. How much was lifted, how far was run, how fast.No registered study measures this.
□Symptoms and quality of lifeNo evidence recorded. Pain, tiredness, mood, sleep, as the person rated it.No registered study measures this.
■A number that stands in for healthEvidence recorded. Cholesterol, blood sugar, bone density. A stand-in, not the thing itself.4 registered measures of this kind.
■A step measured inside a personEvidence recorded. Something measured in human tissue or human cells.A human record sits on the stored organism ladder.
□AnimalsNo evidence recorded. Mice, rats, dogs. Useful for ideas, not proof about people.No animal record is stored.
□Cells in a dishNo evidence recorded. Cells or chemistry on a bench, far from a whole body.No cell or bench record is stored.
□A guess from softwareNo evidence recorded. Nobody measured it. RNAWiki never publishes one as a finding.RNAWiki stores no prediction for this record. Software can suggest a link. RNAWiki does not publish one as a finding.
Higher on these steps means closer to something a person would feel. It does not mean better done.
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
Lorcaserin
What a person takes: Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily.
The measurement behind this step
Oral lorcaserin hydrochloride hemihydrate, immediate-release twice daily or extended-release once daily under a separate application. Well absorbed with extensive hepatic metabolism and renal excretion of metabolites.
Getting in
A tablet twice daily, or an extended-release tablet once daily
Swallowed twice a day, or once a day in the extended-release form.
╌╌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
Oral lorcaserin hydrochloride 10 mg twice daily, or 20 mg once daily as the extended-release product under a separate application. Well absorbed with extensive hepatic metabolism.
Crosses into the brain and reaches the appetite centre
It enters the brain and reaches the hypothalamus, the region that regulates hunger and fullness.
╌╌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
Crosses the blood-brain barrier and reaches the hypothalamic arcuate nucleus and brainstem nuclei. Peripheral exposure is unavoidable, which is why the 5-HT2B selectivity margin matters for heart valves.
It switches on the serotonin receptor that suppresses appetite, while largely avoiding the closely related one found on heart valves.
╌╌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
Agonism at 5-HT2C, a Gq-coupled receptor, with roughly 100-fold selectivity over 5-HT2B and about 15-fold over 5-HT2A at the receptor level — the margin that separates it from norfenfluramine.
The neurons that signal fullness become more active, so meals end sooner and less is eaten.
╌╌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
Activation of 5-HT2C on pro-opiomelanocortin neurons in the arcuate nucleus increases alpha-MSH release onto melanocortin-4 receptors, suppressing food intake. Later work shows lorcaserin also activates brainstem preproglucagon neurons, engaging endogenous GLP-1 signalling.
Weight falls, valves are unaffected, and cancers are slightly more frequent
Nearly four in ten patients lost at least five per cent of their weight, and the heart valve problem was avoided. The reason it is gone is a small cancer excess.
╌╌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
Measured: 38.7 per cent versus 17.4 per cent achieving at least 5 per cent weight loss, odds ratio 3.01. Measured: major adverse cardiovascular events 2.0 versus 2.1 per cent per year, hazard ratio 0.99. Contested: pooled cancer relative risk 1.08 (95% CI 0.96 to 1.23), 476 of 10,342 against 438 of 9,429.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 5 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 it would be like to take◇Read from sources, not yet reviewed
Felt, measured, or meaningful
Three different things that get called the same word. Registered studies measured all three, and mixing them is how a blood test becomes a health claim.
Felt
Things a person could notice without a test.
No registered study measured anything of this kind.
Measured
Things only a test, a scale or a device shows.
body weight
weight loss
waist circumference
post cessation weight change
Meaningful
Things that change how a life goes, not only a number.
No registered study measured anything of this kind.
A registered study says what someone planned to measure. It does not say what they found. A number moving is not the same as a life going better. The two are shown apart here.
Felt, but not shown to help. A person notices a change. No study showed it leads anywhere good.
Measured, but not felt. A number moves. The person notices nothing. Both can be true.
Measured, but not shown to matter. A number moves in the good direction. Nobody showed that lives went better.
Matters, but takes years. The result that counts may take longer than anyone would keep watching.
Names that fit none of the three (9)
weight
adverse events
cardiovascular responses
fmri
time to lapse
smoking withdrawal
cannabis use
adherence to medication
cannabis self administration
These are harms, study-process measures, or names the rules did not recognise. They are shown rather than dropped.
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.
Nobody. Approval of both applications was withdrawn in September 2020, and the FDA determined in March 2021 that the products were not withdrawn for reasons of safety or effectiveness in the sense that governs generic approval.
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.
Where the result stopped carrying
Withdrawal requested 13 February 2020, eight years after approval, on a signal that was not a prespecified endpoint of any trial
Approval of both new drug applications formally withdrawn in September 2020
The trial that produced the fatal finding was designed and powered for a different question, which it answered successfully
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 for a different goal
The studies measured something else entirely.
On this record: Some registered studies measured things that match no goal on this page.
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 (10)
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
Withdrawn
❝ 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
Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily
✎ 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
Professional supervision is normally required. A regulator classifies this substance in a way that restricts how it is supplied.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
Suppression classes recorded: S8.
No source is stored against this line.
What is in the pack
Oral lorcaserin hydrochloride hemihydrate, immediate-release twice daily or extended-release once daily under a separate application. Well absorbed with extensive hepatic metabolism and renal excretion of metabolites.
✎ 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
Withdrawal was requested on 13 February 2020 on a cancer imbalance in the follow-up of CAMELLIA-TIMI 61; pooled across randomised trials the relative risk is 1.08 (95% CI 0.96 to 1.23), driven by lung and pancreatic but not colon cancer in that trial. Cardiovascular safety was demonstrated cleanly, with major adverse cardiovascular events at 0.99 hazard ratio, and serial echocardiography showed no valvulopathy excess. Common adverse effects were headache, dizziness and nausea. Serious hypoglycaemia was more frequent on lorcaserin in diabetic patients (13 versus 4, P = 0.04). Serotonin syndrome is a theoretical risk with concomitant serotonergic drugs.
Nobody counted how many people took this and were fine, so this cannot be turned into a rate.
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.
Lorcaserin appears in spontaneous reports to regulators. Across the 1 most-reported reaction terms, 1 reaction mentions were counted. One report can name several reactions.
The recorded terms (1)
toxic nodular goitre — 1 reaction mentions
open-targets-adr · recorded 2026-06-24 · a recorded source, not a stored snapshot
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
Oral tablet, 10 mg twice daily, or 20 mg extended-release once daily
✎ 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
Well absorbed with extensive hepatic metabolism and renal excretion of metabolites.
✎ 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
3 products list this as an active ingredient in the United States drug directory. 3 of them contain it and nothing else.
FDA National Drug Code directory · 59651-017 · read 2026-08-29
They are sold as powder and tablet.
FDA National Drug Code directory · 59651-017 · read 2026-08-29
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.
Self-experiment planning is not offered for a prescription or clinician-supervised medicine, withdrawn medicine. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Lorcaserin 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 the pooled data establish lorcaserin as carcinogenic — the interval crosses 1 and the reviewers state the evidence does not confirm an increase
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 the 2021 Federal Register determination of "not withdrawn for safety or effectiveness" contradicts the 2020 safety finding; the two documents answer different questions
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 clonal expansion of PIK3CA mutants in rat mammary tissue demonstrates human carcinogenesis
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.
How fast does the body clear it?
The sources RNAWiki checked hold nothing for this field.
Why it matters. Without this, nothing on this page can say how long anything lasts.
What would answer it
A stored source that records 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 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 Lorcaserin 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.
38.7 per cent lost at least 5 per cent of body weight, against 17.4 per cent on placebo
In plain words
In a 12,000-patient trial, nearly four in ten people on lorcaserin lost at least a twentieth of their body weight at one year, against fewer than two in ten on placebo.
What was measured
Proportion achieving at least 5 per cent weight loss at one year
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
CAMELLIA-TIMI 61 (NCT02019264) randomised 12,000 overweight or obese patients with atherosclerotic cardiovascular disease or multiple cardiovascular risk factors to lorcaserin 10 mg twice daily or placebo. At one year, weight loss of at least 5 per cent had occurred in 1,986 of 5,135 patients (38.7 per cent) on lorcaserin against 883 of 5,083 (17.4 per cent) on placebo, odds ratio 3.01 (95% CI 2.74 to 3.30, P < 0.001). Patients on lorcaserin had slightly better blood pressure, heart rate, glycaemic control and lipids. The earlier BLOOM trial (NCT00395135) in 3,182 patients had reported 47.5 per cent against 20.3 per cent at one year, mean loss 5.8 plus or minus 0.2 kg against 2.2 plus or minus 0.1 kg (P < 0.001).
Written into the record, not signed off as a reviewed claim
The cardiovascular safety question was answered cleanly
In plain words
Over 3.3 years the rate of heart attacks, strokes and cardiovascular deaths was the same on the drug as on placebo. That was the question the trial was designed to answer.
What was measured
Annualised rate of major adverse cardiovascular events and echocardiographic valvulopathy rate
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Over a median 3.3 years of follow-up, the primary safety outcome — a composite of cardiovascular death, myocardial infarction or stroke — occurred at 2.0 per cent per year on lorcaserin against 2.1 per cent per year on placebo, hazard ratio 0.99 (95% CI 0.85 to 1.14, P < 0.001 for non-inferiority against a boundary of 1.4). Extended major cardiovascular events, adding heart failure, hospitalisation for unstable angina and coronary revascularisation, occurred at 4.1 against 4.2 per cent per year, hazard ratio 0.97 (0.87 to 1.07, P = 0.55). Adverse events of special interest were uncommon and similar between groups apart from more serious hypoglycaemia on lorcaserin (13 against 4, P = 0.04). Serial echocardiography in the earlier programme, in 2,472 patients at one year and 1,127 at two years, found no increase in cardiac valvulopathy.
Written into the record, not signed off as a reviewed claim
The trial that cleared the heart found a cancer imbalance nobody was testing for
In plain words
The FDA reviewed the long-term follow-up of the safety trial and found more cancers on lorcaserin than on placebo. The drug was withdrawn in February 2020.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The FDA reported in February 2020 an increased risk of cancer with lorcaserin in the follow-up of CAMELLIA-TIMI 61 and requested withdrawal on 13 February 2020, with the agency's own review published as a perspective in the New England Journal of Medicine in September 2020. Cancer was not a prespecified endpoint of the trial. It was a safety trial for cardiovascular outcomes, designed and powered against a non-inferiority boundary of 1.4 for major adverse cardiovascular events, and it delivered a clean answer on that question. The finding that ended the drug came from the same dataset and was not what the dataset was assembled to examine, which places it in exactly the category — an unprespecified imbalance in a large trial — that is hardest to interpret in either direction.
Written into the record, not signed off as a reviewed claim
The pooled relative risk is 1.08, with an interval crossing 1
In plain words
A systematic review pooling every trial found 476 cancers among 10,342 treated patients and 438 among 9,429 on placebo — a relative risk of 1.08 whose range includes no effect.
What was measured
That the pooled trial data establish lorcaserin as carcinogenic in humans
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
A systematic review and meta-analysis searched MEDLINE, Embase and CENTRAL for randomised trials comparing lorcaserin with other interventions or no treatment. From 11 trials comprising 21,299 individuals, four reported new cancer cases and were meta-analysed: 476 cases among 10,342 lorcaserin subjects against 438 among 9,429 on placebo, relative risk 1.08 (95% CI 0.96 to 1.23). The result was heavily influenced by CAMELLIA-TIMI 61, in which the lorcaserin group had higher risk of lung and pancreatic but not colon cancer. Overall risk of bias was low and quality of evidence moderate. The authors conclude that current evidence does not confirm an increased cancer risk but suggests a trend in that direction. That is the honest statement, and it is neither a finding of harm nor a clearance.
Written into the record, not signed off as a reviewed claim
A mechanistic signal was later found in rodent tissue
In plain words
Later laboratory work found that lorcaserin expanded populations of cells carrying a known cancer-driving mutation in rat breast tissue.
What was measured
Clonal expansion of PIK3CA H1047R mutant cells in rat mammary tissue by error-corrected sequencing
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Error-corrected sequencing applied to rat mammary tissue detected lorcaserin-associated clonal expansion of PIK3CA H1047R mutant cells. This is a mechanistic observation in a rodent tissue rather than a demonstration of human carcinogenesis, and clonal expansion of a driver mutation is an intermediate step rather than a tumour. Its evidential value is that it moves the finding from a bare statistical imbalance toward a candidate mechanism, which is the direction of travel a contested safety signal needs. It does not close the question, and the human pooled relative risk remains 1.08 with an interval from 0.96 to 1.23.
Written into the record, not signed off as a reviewed claim
It was built to avoid fenfluramine's failure, and it succeeded at that
In plain words
Lorcaserin was specifically engineered to avoid the receptor that made fenfluramine damage heart valves. Echocardiography in thousands of patients confirmed the design worked.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Fenfluramine was withdrawn in 1997 because its metabolite norfenfluramine agonises the 5-HT2B receptor on cardiac valve interstitial cells, producing fibrotic valve disease. Lorcaserin was designed for selectivity at 5-HT2C over 5-HT2B, and the registration programme tested the point directly with serial echocardiography in 2,472 patients at one year and 1,127 at two years, finding no increase in valvulopathy. The design objective was achieved and independently confirmed. What removed the drug was a hazard that no part of that design programme was aimed at, arising in a trial run to address a third question entirely. Solving the known problem of a class does not narrow the space of unknown ones.
Written into the record, not signed off as a reviewed claim
The formal record says it was not withdrawn for safety or effectiveness
In plain words
Approval was withdrawn in September 2020. Then in March 2021 the FDA formally determined the products were not withdrawn for reasons of safety or effectiveness — a technical finding that permits generic applications.
What was measured
Not recorded
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The Federal Register of 17 September 2020 records Eisai's withdrawal of approval of the two new drug applications for BELVIQ and BELVIQ XR. The Federal Register of 4 March 2021 then records a determination that BELVIQ (lorcaserin hydrochloride) tablets 10 mg and BELVIQ XR were not withdrawn from sale for reasons of safety or effectiveness. That determination is a specific technical finding governing whether abbreviated new drug applications may reference the listed drug; it is not a statement that the cancer imbalance was disproved. A reader consulting the Federal Register and a reader consulting the 2020 safety communication reach opposite impressions, and both documents are accurate about what they address.
Source
Federal Register 17 September 2020, withdrawal of approval of two NDAs for BELVIQ and BELVIQ XR; Federal Register 4 March 2021, determination on withdrawal from sale
Role in the trial
Not matched to a registered study
Identity check
no open identity hold
Audit mark
contested
Review state
Written into the record, not signed off as a reviewed claim
Where else this substance is registered
FDA substance identifier (UNII)
637E494O0Z
CAS registry number
616202-92-7
PubChem compound
11658860
ChEMBL
CHEMBL360328
ChEBI
65353
WHO international nonproprietary name list entry
8765
RxNorm concept
1300701
EMA substance identifier
100000128165
DrugBank
DB04871
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What is missing or unclear◇Read from sources, not yet reviewed
How this medicine reached us
Kept near the foot of the page. A historical event moves up only when it changes something about this substance today.
What the approval register records
1 approved application covers products containing this substance.
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4 questions this page could not answer
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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 selective 5-HT2C agonist that achieved at least 5 per cent weight loss in 38.7 per cent of patients against 17.4 per cent on placebo and passed its cardiovascular safety trial cleanly, then was withdrawn in 2020 because that same trial found cancer in 476 of 10,342 treated patients against 438 of 9,429 on placebo across the pooled programme — a relative risk of 1.08 with a confidence interval from 0.96 to 1.23.
Recorded evidence blocks (10)
Q2
What did Lorcaserin's largest trial (14673 people) and its longest (13 years) measure?
14673 people in Lorcaserin's largest registered study, 13 years in its longest registered window, measuring Mean Differences in POMC Concentrations (Fmol/ml) in CSF After Lorcaserin for One Week Compared to Placebo. ClinicalTrials.gov · 2026-09-01
19 phase1, 14 phase2, 7 phase3, 5 phase4, 2 na or unstated, 1 early phase1, 1 na; NCT02400359; 2027-06; no ageing endpoint recorded. Last human test completed 2021, NCT03253926.
Interpretation These counts include studies where Lorcaserin was a comparison treatment, a background treatment or an exposure in an observational study, and the longest window may be a planned end date. Trial roles have not yet been classified for this record.
Show the evidence
phase1
19
phase2
14
phase3
7
phase4
5
na or unstated
2
early phase1
1
2 more recorded rows
na
1
Last recorded human testNCT03253926
2021-12-31
recorded 2026-09-01 · last checked 2026-09-04
Q3
Lorcaserin was tested only in human — what did it show?
Interpretation Mean Differences in POMC Concentrations (Fmol/ml) in CSF After Lorcaserin for One Week Compared to Placebo — the recorded outcome words.
Show the evidence
humanNCT03353220
biomarker; Mean Differences in POMC Concentrations (Fmol/ml) in CSF After Lorcaserin for One Week Compared to Placebo; 43
Interpretation fMRI (Functional changes in the brain)
Show the evidence
Trial
NCT02400359
"Lorcaserin in Obesity: Identification of CNS Targets Using fMRI"; n 40; "fMRI (Functional changes in the brain)"; 2027-06
NCT04457687
"Extended Access Program With Lorcaserin For The Treatment of Dravet Syndrome and Other Refractory Epilepsies"
recorded 2026-09-01 · last checked 2026-09-04
Q8
Which 12 trials of Lorcaserin posted no result?
Posted no result
12 of 12 completed trials
Registrations
NCT00104507, NCT00116740, NCT00828581, NCT00828724, NCT00828932 and NCT00828438, and 6 more
Completion dates
oldest 2005-05; newest 2019-04-11
Show the evidence
Trial
NCT00104507
2005-05
NCT00116740
2005-11
NCT00828581
2008-12
NCT00828724
2008-12
NCT00828932
2008-12
NCT00828438
2009-02
6 further recorded trials
NCT02398669
2015-05
NCT02393599
2015-09
NCT02192515
2016-01
NCT03627936
2018-09-02
NCT02932215
2019-01-17
NCT03552107
2019-04-11
Q9
At the median, Lorcaserin's trials enrolled 32 people — anything larger?
Median enrolment
32
Largest enrolment
14673
Registered trials counted
42
Q10
What do 1 spontaneous reports say about Lorcaserin — 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.
Lorcaserin appears in spontaneous reports to regulators. Across the 1 most-reported reaction term, 1 reaction mentions were counted: toxic nodular goitre 1. open-targets-adr · CHEMBL2095211 · 2026-06-24
Show the evidence
toxic nodular goitre
1
recorded 2026-06-24 · last checked 2026-09-04
Q11
Was Lorcaserin studied with fasting and exercise?
fasting and exercise are named in Lorcaserin's label sentences: "Compared with placebo, lorcaserin not only reduced weight, BMI and waist circumference but also improved SBP, DBP, heart rate, LDL, triglycerides, fasting plasma glucose and HbA1c." openfda-label+europepmc · 2019-09-23
2 recorded statements; fasting, exercise
Show the evidence
fasting
Compared with placebo, lorcaserin not only reduced weight, BMI and waist circumference but also improved SBP, DBP, heart rate, LDL, triglycerides, fasting plasma glucose and HbA1c.
exercise
The approvals were based on 1-year trials showing that on top of recommendations to follow a calorie-restricted diet and to increase exercise, patients randomized to either drug lost more weight than patients randomized to placebo (3% [95% CI, 3%-4%] more weight lost with lorcaserin; 7% [95% CI, 3%-4%] more with phentermine /topiramate).
recorded 2019-09-23 · last checked 2026-09-04
Where it is registeredIdentifiers, relations and other names
ClinicalTrials.gov — US Government work · Europe PMC — metadata only, under the recorded legal gate · Open Targets 26.06 — CC0 · derived from this page's own recorded fields; no external licence · mixed register set; per-register licences in docs/specs/corpus-20k-sources.md · openFDA / DailyMed — US Government work
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