This page shows what was measured, who it was measured in, and what that does not settle.
What Olanzapine does in the body
Olanzapine blocks dopamine receptors, which is what reduces hallucinations and delusions, and it holds on to them more tightly and for longer than quetiapine does.
It also blocks a serotonin receptor and a histamine receptor in the part of the brain that decides when you have eaten enough. Those two receptors are why it works better than most antipsychotics and why it is the hardest of them on body weight and blood sugar. The same appetite effect is what makes it useful against the nausea of chemotherapy and in anorexia nervosa.
Why people take it. Schizophrenia, and the manic and mixed phases of bipolar disorder
What happened in people
A standardised mean difference of 0.59 against placebo for overall symptom change, third of fifteen ranked antipsychotics across 212 trials and 43,049 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.
That the samidorphan combination removes the weight problem — it reduced mean gain from 6.59% to 4.21% and left 27.5% of patients gaining 7% or more
Where it acts
Mesolimbic and mesocortical dopamine synapses, plus hypothalamic serotonin 5-HT2C and histamine H1 receptors that govern appetite
Kind of result
Symptoms and quality of life
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
Its recorded molecular formula is C17H20N4S, weighing 312.44.
US prescribing information · 4d768cfe-3b20-4127-95b9-b4151b28afcc · read 2026-08-30
Where each sentence above came from
A person wrote this explanation into the record, with the studies named in the path below.
The recorded use, written for a reader without medical training. Not signed off.
A limit recorded against this substance. Not signed off as a reviewed claim.
The four opening statements run to 126 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.
Placebo
A placebo is a dummy treatment given so the real one can be compared with it.
A picture of it, and where the picture fails
A placebo is like a blank control in an experiment.
Where that stops being true. A blank does nothing. People given a placebo often do get better.
What people get wrong. A placebo effect is read as imaginary. The improvement is measured and real.
An inactive intervention matched in appearance to the test intervention, used to control for non-specific effects.
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.
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.
Time to discontinuation of assigned antipsychotic for any cause
✓ The study showed what it set out to show
Who was studied
CATIE phase 1 (NCT00014001)
How many people
1493
Study design
Phase 4 independent randomised double-blind effectiveness trial, up to 18 months
Compared against
Not recorded for this study
Kind of result
A number that stands in for health
What was found
P < 0.001 for longer time to discontinuation on olanzapine than quetiapine, P = 0.002 versus risperidone; 64% of the olanzapine arm still discontinued
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. Olanzapine accounted for more discontinuation for weight gain or metabolic effects than any other arm, and did not significantly beat perphenazine, a first-generation drug from 1957.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
P = 0.002 for nausea prevention over 120 hours (37% versus 22%); P < 0.001 for complete response (64% versus 41%)
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. Severe sedation on day 2 in 5% of the olanzapine arm. Antiemesis is not an FDA-approved indication for olanzapine, so this National Cancer Institute result supports a use outside the label.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Rate of change in body weight and rate of change in obsessionality on the Yale-Brown Obsessive Compulsive Scale
✗ The study did not show it
Who was studied
Attia anorexia nervosa trial
How many people
152
Study design
Randomised double-blind placebo-controlled trial, 16 weeks, five sites
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
Significant treatment-by-time interaction for BMI (0.259 versus 0.095 units per month); no significant difference in YBOCS obsessions change (-0.325 versus -0.017 points per month)
Repeated elsewhere
Unreplicated
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. One co-primary endpoint was met and the other was not. A page that reports only the weight result describes half the trial.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
Weight change 4.21% versus 6.59%, difference -2.38% (SE 0.76), significant; 10% or greater gain in 17.8% versus 29.8%, odds ratio 0.50
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. The comparator was olanzapine, not placebo. Both arms gained weight; 27.5% of the combination arm still gained 7% or more of body weight in 24 weeks.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 5 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
Olanzapine
What a person takes: Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot.
The measurement behind this step
The oral half-life of roughly a day supports once-daily dosing. The orally disintegrating form exists for situations where swallowing cannot be confirmed. The pamoate depot releases olanzapine over two to four weeks and must be given in a registered healthcare facility with a post-injection observation period, because a portion of the depot can enter a blood vessel and produce sudden sedation or delirium.
Getting in
Taken by mouth, or dissolved on the tongue, or injected
A standard tablet, an orally disintegrating wafer for people who will not reliably swallow, a short-acting injection for acute agitation, and a long-acting depot given every two to four weeks in a clinic.
╌╌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 bioavailability is unaffected by food; the terminal half-life is roughly 21 to 54 hours, which supports once-daily dosing. Clearance is hepatic, dominated by direct glucuronidation and CYP1A2. Smoking induces CYP1A2 and lowers exposure substantially, which is why smoking status changes the concentration achieved from the same amount.
It crosses into the brain and reaches the appetite centres too
The molecule is lipophilic and crosses into the brain readily. It does not go only to the regions that matter for psychosis: it reaches the hypothalamus, where hunger and fullness are regulated.
──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
High unbound brain-to-plasma partitioning with distribution throughout the central nervous system, including hypothalamic nuclei expressing 5-HT2C and H1 receptors. The absence of regional selectivity is the structural reason the therapeutic effect and the metabolic effect cannot be separated by dosing.
Unlike quetiapine, olanzapine grips the dopamine receptor firmly and comes off slowly, so the block is sustained between doses. That is why it controls symptoms better, and why stiffness and restlessness are still possible.
╌╌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 antagonism at D1 to D4 with slow dissociation from D2, giving sustained striatal occupancy across the dosing interval. Concurrent 5-HT2A antagonism moderates the extrapyramidal consequences of that occupancy, but does not abolish them at the higher end of the licensed range.
It also blocks the receptors that tell you when you have eaten enough
The same molecule blocks a serotonin receptor and a histamine receptor in the brain's appetite centre. Hunger increases, fullness arrives later, and weight goes up. This is not a side effect that can be dialled out, because it is the same molecule doing both jobs.
╌╌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
Antagonism at 5-HT2C removes a satiety brake and at H1 removes a second one, with downstream effects on hypothalamic AMPK signalling and on peripheral insulin sensitivity. Muscarinic M3 blockade has been proposed as a direct contributor to impaired insulin secretion. The measured consequence is the largest weight effect of fifteen ranked antipsychotics.
Symptoms fall further than with most alternatives, and so does the tolerability
On the scales trials use, olanzapine outperforms almost every other antipsychotic except clozapine. In the long independent trial it also kept more people on treatment than any other drug, while losing more of them specifically to weight and metabolic problems.
╌╌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
Standardised mean difference against placebo of 0.59 (95% CrI 0.53 to 0.65) for overall symptom change, third of fifteen. Weight gain standardised mean difference of -0.74 against placebo, worst of fifteen. In CATIE, discontinuation attributable to weight gain or metabolic effects was concentrated in the olanzapine arm.
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 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.
People with schizophrenia and bipolar disorder, people receiving highly emetogenic chemotherapy, and, in smaller numbers, adults with anorexia nervosa. The oncology use is supported by a National Cancer Institute trial and is not an FDA-approved indication.
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: “Safety and effectiveness of olanzapine in children <13 years of age have not been established [see Patient Counseling Information (17) ] .”
US prescribing information · 4d768cfe-3b20-4127-95b9-b4151b28afcc · read 2026-08-30
On older people, the label states: “Clinical studies of olanzapine and fluoxetine in combination did not include sufficient numbers of patients ≥65 years of age to determine whether they respond differently from younger patients.”
US prescribing information · 4d768cfe-3b20-4127-95b9-b4151b28afcc · read 2026-08-30
On people who are pregnant, the label states: “Pregnancy Exposure Registry There is a pregnancy exposure registry that monitors pregnancy outcomes in women exposed to atypical antipsychotics, including olanzapine, during pregnancy.”
US prescribing information · 4d768cfe-3b20-4127-95b9-b4151b28afcc · read 2026-08-30
On people who are breastfeeding, the label states: “8.3 Females and Males of Reproductive Potential Infertility Females Based on the pharmacologic action of olanzapine (D 2 receptor antagonism), treatment with olanzapine may result in an increase in serum prolactin levels, which may lead to a reversible reduction in fertility in females of reproductive potential [see Warnings and Precautions (5.15) ] .”
US prescribing information · 4d768cfe-3b20-4127-95b9-b4151b28afcc · read 2026-08-30
Where the result stopped carrying
CATIE's primary endpoint was met on olanzapine and still recorded 64% discontinuation, with olanzapine leading the arms for discontinuation due to weight and metabolic effects
The obsessionality co-primary endpoint in the anorexia nervosa trial was not met
The long-acting injectable formulation produced a syndrome resembling overdose in 1.4% of trial patients, with no identifiable risk factors
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
Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
✎ 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: S5, S6, S9.
No source is stored against this line.
What is in the pack
The oral half-life of roughly a day supports once-daily dosing. The orally disintegrating form exists for situations where swallowing cannot be confirmed.
✎ 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. The rest of the recorded wording: The pamoate depot releases olanzapine over two to four weeks and must be given in a registered healthcare facility with a post-injection observation period, because a portion of the depot can enter a blood vessel and produce sudden sedation or delirium.
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
The United States label carries a boxed warning for increased mortality in elderly patients with dementia-related psychosis; the long-acting injection carries a second boxed warning for post-injection delirium and sedation syndrome. Weight gain, hyperglycaemia, dyslipidaemia and increased appetite are the defining tolerability problems. The class risks of tardive dyskinesia, neuroleptic malignant syndrome and orthostatic hypotension apply. Smoking lowers olanzapine concentrations through CYP1A2 induction, so starting or stopping smoking changes exposure.
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
Oral tablet, orally disintegrating tablet, short-acting intramuscular injection, and a long-acting intramuscular pamoate depot
✎ 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
The orally disintegrating form exists for situations where swallowing cannot be confirmed.
✎ 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. The rest of the recorded wording: The pamoate depot releases olanzapine over two to four weeks and must be given in a registered healthcare facility with a post-injection observation period, because a portion of the depot can enter a blood vessel and produce sudden sedation or delirium.
No source is stored against this line.
What is recorded as being sold
292 products list this as an active ingredient in the United States drug directory. 269 of them contain it and nothing else.
FDA National Drug Code directory · 72241-053 · read 2026-08-29
They are sold as capsule, injection, powder, for solution, injection, powder, for suspension, extended release, injection, powder, lyophilized, for solution, powder and powder, for suspension, taken intramuscular and oral.
FDA National Drug Code directory · 72241-053 · read 2026-08-29
The regulator's established pharmacologic class for it is atypical antipsychotic [epc].
FDA National Drug Code directory · 72241-053 · read 2026-08-29
108 published labels name it as an active ingredient. 104 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 3c28cf18-01a3-468a-ab3e-8aa82f918251 · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 3c28cf18-01a3-468a-ab3e-8aa82f918251 · read 2026-08-29
Olanzapine is orally disintegrating tablets at Orally Disintegrating Tablets: 5 mg, 10 mg, 15 mg, 20 mg, recorded as prescription product; fda label in effect 2023-07-10 in the United States.
US prescribing information · 002dd00f-7946-ea4f-e063-6294a90a5916 · read 2026-08-27
Recorded price in US: 0.08099–21.36767 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 102 priced products whose strengths and pack forms differ, as of 2026-08-26, paid by retail pharmacies buying the product, as surveyed by the Centers for Medicare & Medicaid Services. It is not a list price, an insurance price, or what anyone pays at a counter..
Recorded source · 2026-08-26 · read 2026-08-28
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. The questions below are for a clinician or pharmacist.
Questions worth asking
Which of the trials of Olanzapine 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 samidorphan combination removes the weight problem — it reduced mean gain from 6.59% to 4.21% and left 27.5% of patients gaining 7% or more
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 olanzapine treats anorexia nervosa — it changed the rate of weight gain and did not change the obsessional thinking that defines the disorder
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 being the most effective non-clozapine antipsychotic makes it the right first choice for everyone — the same analysis ranks it last of fifteen on weight
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 metabolic effect can be avoided by using less — the receptors that drive appetite are bound at lower concentrations than those that control symptoms
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 Olanzapine 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.
CATIE: the only arm where most patients had not quit by 18 months was still 64%
In plain words
In the largest independent schizophrenia trial ever run, olanzapine kept more people on treatment than any of the other four drugs. It still lost roughly two-thirds of its patients within eighteen months.
What was measured
Time to discontinuation of assigned treatment for any cause over 18 months
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
CATIE randomised 1,493 patients with chronic schizophrenia at 57 United States sites to olanzapine, perphenazine, quetiapine, risperidone or ziprasidone for up to 18 months, with time to all-cause discontinuation as the primary outcome. Of 1,432 patients who took at least one dose, 74% discontinued: 64% on olanzapine, 74% on risperidone, 75% on perphenazine, 79% on ziprasidone and 82% on quetiapine. Time to discontinuation was significantly longer on olanzapine than on quetiapine (P<0.001) or risperidone (P=0.002), but not significantly longer than on perphenazine (P=0.021) or ziprasidone (P=0.028) at the trial's adjusted threshold. The rates of discontinuation for intolerable side effects differed across groups (P=0.04), with olanzapine accounting for more discontinuation for weight gain or metabolic effects. The trial was funded by the National Institute of Mental Health.
Written into the record, not signed off as a reviewed claim
Third of fifteen on efficacy, last of fifteen on weight
In plain words
Pooling 212 trials and 43,049 patients, olanzapine was the third most effective antipsychotic on symptom scores, behind only clozapine and amisulpride. In the same analysis it caused more weight gain than any of the other fourteen.
What was measured
Standardised mean difference against placebo for overall symptom change and for weight gain
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In the Leucht multiple-treatments meta-analysis, standardised mean differences against placebo for overall symptom change were clozapine 0.88 (95% CrI 0.73 to 1.03), amisulpride 0.66 and olanzapine 0.59 (0.53 to 0.65), ahead of risperidone 0.56, paliperidone 0.50, haloperidol 0.45, quetiapine 0.44, aripiprazole 0.43, ziprasidone 0.39 and lurasidone 0.33. On weight gain, the standardised mean differences against placebo ran from -0.09 for haloperidol, the best, to -0.74 for olanzapine, the worst of the fifteen. In the 2019 update covering 402 trials, olanzapine remained among the drugs with significantly increased anticholinergic effects against placebo.
Written into the record, not signed off as a reviewed claim
The strongest randomised result is in oncology, for an unapproved use
In plain words
A National Cancer Institute trial gave olanzapine or a dummy pill to 380 people starting the harshest kind of chemotherapy, on top of the standard anti-sickness drugs. Over five days, 37% on olanzapine had no nausea at all against 22% on placebo.
What was measured
Proportion of patients with no chemotherapy-induced nausea over 120 hours, and complete response rate
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Navari and colleagues ran a randomised double-blind phase 3 trial in patients with no previous chemotherapy receiving cisplatin at 70 mg/m2 or more, or cyclophosphamide with doxorubicin. All patients received dexamethasone, aprepitant or fosaprepitant and a 5-HT3 antagonist; 192 were assigned olanzapine 10 mg and 188 placebo on days 1 to 4. The proportion with no chemotherapy-induced nausea was 74% versus 45% in the first 24 hours (P=0.002), 42% versus 25% from 25 to 120 hours (P=0.002) and 37% versus 22% over the full 120 hours (P=0.002). Complete response rates were 86% versus 65% (P<0.001), 67% versus 52% (P=0.007) and 64% versus 41% (P<0.001). Severe sedation occurred in 5% on day 2. The trial was funded by the National Cancer Institute. Antiemesis is not an FDA-approved indication for olanzapine.
Written into the record, not signed off as a reviewed claim
The drug built to remove the weight gain removes about a third of it
In plain words
A combination product was developed to keep olanzapine and cancel its weight gain. In a 561-patient trial it cut average weight gain from 6.6% of body weight to 4.2%. That is a real reduction and it is not a cancellation.
What was measured
That combining olanzapine with samidorphan solves its metabolic problem — the measured result is a 2.38 percentage point reduction on a 6.59% gain, not an elimination
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Correll and colleagues randomised 561 adults with schizophrenia to olanzapine combined with samidorphan (n=280) or olanzapine alone (n=281) for 24 weeks, with percent change in body weight and the proportion gaining 10% or more as co-primary endpoints. Least-squares mean weight change was 4.21% (SE 0.68) on the combination against 6.59% (SE 0.67) on olanzapine, a significant difference of -2.38% (SE 0.76). Weight gain of 10% or more occurred in 17.8% against 29.8% (number needed to treat 7.29, odds ratio 0.50) and of 7% or more in 27.5% against 42.7% (number needed to treat 6.29, odds ratio 0.50). Schizophrenia symptom improvement was similar between groups, which is expected because the antipsychotic component is identical. Marketing that describes the product as mitigating weight gain is accurate; reading it as preventing weight gain is not, because more than a quarter of patients still gained 7% or more of their body weight in 24 weeks.
Written into the record, not signed off as a reviewed claim
In anorexia nervosa it moved weight and did not touch the illness
In plain words
A five-site randomised trial in 152 adults with anorexia nervosa found olanzapine increased the rate of weight gain compared with a dummy pill. It made no difference at all to the obsessional thinking that drives the disorder.
What was measured
Rate of change in BMI per month and rate of change in YBOCS obsessions subscale score
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
Attia and colleagues randomised 152 adult outpatients with anorexia nervosa, 96% women, mean body mass index 16.7, to olanzapine (n=75) or placebo (n=77) for 16 weeks at five North American sites. The co-primary outcomes were rate of change in body weight and rate of change in obsessionality on the Yale-Brown Obsessive Compulsive Scale. The treatment-by-time interaction for BMI was significant: 0.259 (SD 0.051) units per month on olanzapine against 0.095 (SD 0.053) on placebo. Change in the YBOCS obsessions subscale did not differ (-0.325 against -0.017 points per month), and there was no significant difference in the frequency of abnormal metabolic laboratory results. The authors describe the weight effect as modest and note there was no significant benefit for psychological symptoms.
Written into the record, not signed off as a reviewed claim
The long-acting injection has a syndrome that looks like an overdose
In plain words
The depot form of olanzapine can accidentally deliver part of the injection into a blood vessel, producing sudden heavy sedation or confusion that looks like an overdose. It happened after roughly one injection in 1,400 and to about one patient in 70.
What was measured
Incidence of post-injection delirium/sedation syndrome per injection and per patient, and time to onset
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
A review of safety data from all completed and ongoing trials of olanzapine long-acting injection, covering approximately 45,000 injections given to 2,054 patients through 14 October 2008, identified post-injection delirium or sedation syndrome in about 0.07% of injections and 1.4% of patients: 30 events in 29 patients. Presentations were consistent with olanzapine overdose, including sedation, confusion, slurred speech, altered gait or unconsciousness, with no clinically significant change in vital signs. Onset ranged from immediate to three to five hours, median 25 minutes. All patients recovered within 1.5 to 72 hours and most continued to receive further injections. No clear risk factors were identified. The mechanism proposed is accidental partial intravascular injection. The finding is why the product requires administration in a registered healthcare facility with a post-injection observation period.
Written into the record, not signed off as a reviewed claim
The uses beyond the licence were promoted, and settled for US$1.415 billion in 2009
In plain words
In January 2009 the manufacturer agreed to pay one of the largest pharmaceutical settlements ever recorded in the United States over the promotion of olanzapine for uses the FDA had not approved.
What was measured
That prescribing volume reflects clinical evidence — for this drug part of it reflects promotion that was found unlawful
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The United States Department of Justice announced in January 2009 that Eli Lilly and Company had agreed to pay US$1.415 billion to resolve allegations of off-label promotion of Zyprexa, including a criminal fine and a civil settlement. The conduct at issue concerned promotion for uses outside the approved indications in elderly populations. The relevance to this page is not the money: it is that the size of the real-world exposure to a drug, and therefore the size of the population in which its metabolic effects were expressed, was shaped by promotion rather than by the trials that supported the licence.
Source
United States Department of Justice, Office of Public Affairs, 15 January 2009: "Eli Lilly and Company Agrees to Pay $1.415 Billion to Resolve Allegations of Off-label Promotion of Zyprexa"
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
How many documents were read
104 documents were read for this substance.
RNAWiki source record
103 of them state the same tMax, and they agree.
RNAWiki source record
Where else this substance is registered
FDA substance identifier (UNII)
N7U69T4SZR
CAS registry number
132539-06-1
PubChem compound
135398745
RxNorm concept
1294588
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Trial roles classified for highlighted evidence
No registered study is classified as testing this substance.
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Safety mode resolved
Suppression classes recorded: S5, S6, S9.
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Canonical metadata present
slug and display name present
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
57 approved applications cover products containing this substance. The earliest was NDA020592, approved 19960930 to CHEPLAPHARM.
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What is not here
7 questions this page could not answer
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Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
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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.
The most effective non-clozapine antipsychotic on both the 212-trial pooled ranking (standardised mean difference 0.59) and the largest independent head-to-head trial ever run, where it also had the worst weight gain of fifteen ranked drugs, and whose single cleanest randomised result is in a condition it is not approved for: preventing chemotherapy nausea, 37% versus 22% nausea-free over five days in 380 patients.
Recorded evidence blocks (11)
Q2
On the Olanzapine label: indicated for what?
"Olanzapine for Injection is an atypical antipsychotic indicated for the: Treatment of acute agitation associated with schizophrenia and bipolar I mania. ( 1.4 ) Efficacy was established in three 1-day trials in adults.": indications and usage on Olanzapine's label. DailyMed label · 63bcfe98-d1fc-4cd7-9212-f59ee4dcc6d1 · 2026-08-25
Q3
368 registered trials of Olanzapine — at which phases?
Registered studies posting no result
272 of 368
368 registered studies of Olanzapine: 110 phase3, 106 phase4, 59 phase2, 46 na, 39 phase1, 19 na or unstated, 3 early phase1. CLINICALTRIALS_SNAPSHOT · 2026-09-01
terminated; "Trial discontinued due to low enrollment"
NCT00885690
terminated; "Due to recruitment problems"
NCT00910780
withdrawn; "Study was not funded."
NCT00931996
terminated; "Study was terminated due to low accrual."
NCT01129674
terminated; "The decision to stop the trial was based on efficacy results in the overall schizophrenia participant population."
NCT01148264
terminated; "poor enrolment"
NCT01184443
terminated; "Poor recruitment"
NCT01193166
withdrawn; "This study was stopped due to an internal reconsideration of priorities of the product portfolio."
NCT01420575
terminated; "Low enrollment rate."
NCT01625923
terminated; "Inadequate recruitment numbers"
recorded 2026-09-01 · last checked 2026-09-04
Q5
Human studies of Olanzapine used olanzapine (15 mg) — over how long?
studies of Olanzapine used the recorded amount. ClinicalTrials.gov · 2026-09-01
20 recorded entries; human; also "olanzapine (15 mg)", "Olanzapine Tablets 5 mg", "Zyprexa® Tablets 5 mg"
Show the evidence
human
NCT00265551
olanzapine (15 mg)
NCT00647777
Olanzapine Tablets 5 mg
NCT00647777
Zyprexa® Tablets 5 mg
NCT00647972
Olanzapine Tablets 20 mg
NCT00647972
Zyprexa® Tablets 20 mg
NCT00741026
Olanzapine 10 mg po qhs for 3 days
14 more recorded rows
humanNCT00746785
2.5 mg Olanzapine
humanNCT00746785
5mg Olanzapine
humanNCT01503437
Olanzapine OD Tablets 5 mg
humanNCT01996488
Olanzapine Orally Disintegrating Tablets 5mg
humanNCT01996501
Olanzapine Orally Disintegrating 5mg Tablets
humanNCT02536846
Zyprexa Zydis 5 mg tb
humanNCT03246620
Olanzapine oro-dispersible 5Mg Tab
humanNCT03679182
olanzapine 5 mg Tab
humanNCT03741478
OLANZapine 2.5 MG
humanNCT03876938
olanzapine 10 mg
humanNCT03876938
olanzapine 5 mg
humanNCT04075955
Zyprexa® (OLANZapine 5MG)
humanNCT04232423
Olanzapine 10 Mg ORAL TABLET
humanNCT04232423
Olanzapine 5 Mg ORAL TABLET
recorded 2026-09-01 · last checked 2026-09-04
Q6
Olanzapine's half-life is 21 to 54 hours — which schedules were studied?
21 to 54 hours, the half-life Olanzapine's label states: "Its half-life ranges from 21 to 54 hours (5th to 95th percentile; mean of 30 hr), and apparent plasma clearance ranges from 12 to 47 L/hr (5th to 95th percentile; mean of 25 L/hr)." DailyMed label · 63bcfe98-d1fc-4cd7-9212-f59ee4dcc6d1 · 2026-08-25
tmax 6 hours.
Show the evidence
half lifepharmacokinetics
21 to 54 hours; Its half-life ranges from 21 to 54 hours (5th to 95th percentile; mean of 30 hr), and apparent plasma clearance ranges from 12 to 47 L/hr (5th to 95th percentile; mean of 25 L/hr).
tmaxpharmacokinetics
6 hours; Oral Administration, Monotherapy — Olanzapine is well absorbed and reaches peak concentrations in approximately 6 hours following an oral dose.
metabolismpharmacokinetics
It is eliminated extensively by first pass metabolism, with approximately 40% of the dose metabolized before reaching the systemic circulation.
recorded 2026-08-25 · last checked 2026-09-04
Q7
Which running trial of Olanzapine could settle insulin sensitivity?
3 open trials; n 64; "Intranasal Insulin and Olanzapine Study in Healthy Volunteers"
Show the evidence
Trial
NCT03741478
"Intranasal Insulin and Olanzapine Study in Healthy Volunteers"; n 64; "Endogenous Glucose Production: Pancreatic Euglycemic Clamp Experiments"; 2026-07-30
NCT06554613
"Olanzapine Impact on First-line Immunotherapy for Advanced EGFR-negative NSCLC"; n 156; "The Overall Survival（OS）"; 2027-05-31
NCT05895838
"The Danish Out-of-Hospital Cardiac Arrest Study"; n 1000; "Steroid intervention primary endpoint: All-cause mortality"; 2027-12
Q8
Which 159 trials of Olanzapine posted no result?
Posted no result
159 of 159 completed trials
Registrations
NCT00065273, NCT00169065, NCT00036088, NCT00034580, NCT00034801 and NCT00647777, and 153 more
Completion dates
oldest 2001-06; newest 2024-03-20
Show the evidence
Trial
NCT00065273
2001-06
NCT00169065
2002-06
NCT00036088
2002-07
NCT00034580
2002-08
NCT00034801
2003-03
NCT00647777
2003-07
14 further recorded trials
NCT00648921
2003-07
NCT00236379
2003-08
NCT00485823
2003-09
NCT00486005
2003-10
NCT00485498
2003-12
NCT00712686
2003-12
NCT00177567
2004-01
NCT01282632
2004-03
NCT00621998
2004-06
NCT00181935
2004-07
NCT01123408
2004-07
NCT00255879
2004-08
NCT00018668
2004-09
NCT00015548
2004-10
Q9
At the median, Olanzapine's trials enrolled 105 people — anything larger?
Median enrolment
105
Largest enrolment
1037352
Registered trials counted
361
Q10
What do 4591 spontaneous reports say about Olanzapine — 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.
Olanzapine appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 4591 reaction mentions were counted: weight increased 802; sedation 577; diabetes mellitus 559; suicide attempt 494. FAERS via Open Targets · CHEMBL3989694 · 2026-06-24
Show the evidence
weight increased
802
sedation
577
diabetes mellitus
559
suicide attempt
494
somnolence
464
blood glucose increased
403
4 more recorded rows
confusional state
341
agitation
324
hypertension
320
dyskinesia
307
recorded 2026-06-24 · last checked 2026-09-04
Q11
Which 10 reactions does Olanzapine's label not list?
Inducers of CYP1A2 — Carbamazepine therapy (200 mg bid) causes an approximately 50% increase in the clearance of olanzapine.
drug_interactions
This increase is likely due to the fact that carbamazepine is a potent inducer of CYP1A2 activity.
drug_interactions
Inhibitors of CYP1A2 Fluvoxamine: Fluvoxamine, a CYP1A2 inhibitor, decreases the clearance of olanzapine.
drug_interactions
Inhibitors of CYP2D6 Fluoxetine: Fluoxetine (60 mg single dose or 60 mg daily dose for 8 days) causes a small (mean 16%) increase in the maximum concentration of olanzapine and a small (mean 16%) decrease in olanzapine clearance.
drug_interactions
Inducers of CYP1A2 or Glucuronyl Transferase — Omeprazole and rifampin may cause an increase in olanzapine clearance.
drug_interactions
Effect of Olanzapine on Drug Metabolizing Enzymes — In vitro studies utilizing human liver microsomes suggest that olanzapine has little potential to inhibit CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A.
2 more recorded rows
Interaction statementpharmacokinetics
Direct glucuronidation and cytochrome P450 (CYP) mediated oxidation are the primary metabolic pathways for olanzapine.
Interaction statementpharmacokinetics
CYP2D6 mediated oxidation appears to be a minor metabolic pathway in vivo, because the clearance of olanzapine is not reduced in subjects who are deficient in this enzyme.
ChEMBL 37 — CC BY-SA 3.0 Unported · 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
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