This page shows what was measured, who it was measured in, and what that does not settle.
What Risedronic acid does in the body
Thinning, fragile bones that break more easily than they should
Like alendronate it sticks to bone mineral and is swallowed by the cells that dissolve bone. Inside them it blocks the same enzyme, and it blocks it far harder. That extra potency does not translate into a better result in people, because how much drug reaches the cell is set by how strongly it binds the mineral and how much of the tablet was absorbed, not by how tightly it grips the enzyme.
What happened in people
Hip fracture 1.9% against 3.2% over three years in 5445 women aged 70-79 with osteoporosis, RR 0.6 (95% CI 0.4 to 0.9)
✎ 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 only oral bisphosphonate whose pivotal programme declared hip fracture, rather than a radiographic vertebral fracture, as a primary endpoint
Where it acts
The resorption pit under an osteoclast — the same site as alendronate, reached the same way
Kind of result
The kind of result is not recorded
Supervision
RNAWiki has not recorded a supervision or regulatory status for this substance.
What the registries record it as
The substance registry classes this as chemical.
FDA substance registry · KM2Z91756Z · 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 112 words.
Words this page uses
Four words worth knowing first
Chosen from what this page shows, with each one explained before the word it depends on.
Comparator
A comparator is whatever the treatment was measured against.
A picture of it, and where the picture fails
It is like the other runner in a race.
Where that stops being true. A race has one winner. A study can show both arms improved.
What people get wrong. Results are read without asking what the other group got. Beating nothing is not beating a treatment.
The control condition against which the experimental intervention is assessed.
Randomisation
Randomisation means chance decides who gets which treatment.
A picture of it, and where the picture fails
It is like a coin toss deciding the groups.
Where that stops being true. A coin toss is fair once. Fairness here comes from doing it for everyone.
What people get wrong. It is thought to make groups identical. It makes them similar on average, including on things nobody measured.
Allocation of participants to arms by a chance process, so that unmeasured factors are balanced in expectation.
Absolute difference
An absolute difference is how many more people in a hundred were affected.
A picture of it, and where the picture fails
It is like counting heads in two rooms of a hundred.
Where that stops being true. Heads are easy to count. Study results carry a margin of error too.
What people get wrong. It is confused with a percentage change, which can look far larger.
The arithmetic difference in event rates between arms.
Confidence interval
A confidence interval is the range the true answer is likely to sit in.
A picture of it, and where the picture fails
It is like a weather forecast giving a range rather than one number.
Where that stops being true. A forecast range covers tomorrow. This one covers what the study could resolve.
What people get wrong. The middle number is read as the answer. A range crossing zero means no change is still possible.
An interval estimate that would contain the true parameter in a stated proportion of repeated studies.
What happened in people◇Read from sources, not yet reviewed
What happened in people
Each card is one study: the exact question it asked, who was in it, and whether it showed what it set out to show.
New vertebral fracture by quantitative and semiquantitative radiography
Hip Intervention Program, group aged 80 and over (McClung 2001)
How many people
3886
Study design
Phase 3, randomised, placebo-controlled
Compared against
A dummy treatment
Kind of result
A number that stands in for health
What was found
4.2% against 5.1%, P=0.35
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. This group was enrolled mainly on non-skeletal risk factors such as poor gait or a tendency to fall. The null result is a finding about who a resorption inhibitor can help, and it is usually reported only as part of the pooled 2.8% against 3.9%.
How far it carries. This study is recorded from the curated record, not from the registry match.
Form and route. Oral immediate-release tablet and oral delayed-release tablet
Interval reported. Not recorded in this summary
Written into the record, not signed off as a reviewed claim.
RNAWiki holds 4 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
Risedronic acid
What a person takes: Oral immediate-release tablet and oral delayed-release tablet.
The measurement behind this step
The immediate-release tablet is taken fasting with plain water and the patient stays upright. The delayed-release tablet uses an enteric coat with a chelating agent so it can be taken immediately after breakfast, which is the only real formulation innovation in the oral bisphosphonates.
Getting in
Under one percent of the tablet is absorbed
Like every oral drug in this class it is barely absorbed, and food makes it worse. A delayed-release version exists specifically so it can be taken after breakfast instead.
╌╌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
Mean absolute oral bioavailability of the 30 mg immediate-release tablet taken four hours before a meal is 0.63% (90% CI 0.54% to 0.75%). The delayed-release tablet loses about 30% of its bioavailability when taken immediately after a high-fat breakfast, but is still two to four times better absorbed in that setting than the immediate-release tablet taken 30 minutes before the same meal.
Most of what is absorbed goes to bone; the rest is passed in urine
The molecule has almost no interest in soft tissue. It finds bone mineral, binds, and waits there.
──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
Preclinical intravenous studies show roughly 60% of a dose distributed to bone with the remainder excreted unchanged in urine. Mean steady-state volume of distribution is 13.8 L/kg and plasma protein binding about 24%, markedly lower than alendronate’s 78%.
The osteoclast dissolves the mineral and takes the drug in with it
The cell that eats bone cannot avoid eating the drug. The acid it uses to dissolve mineral is what releases the drug in the first place.
╌╌Described, with no measurement named. No measurement is named for this step, so it is drawn as an unconfirmed link.
The measurement behind this step
The sealing zone under a resorbing osteoclast holds pH near 4.5, liberating adsorbed bisphosphonate into the lacuna, from which it enters by fluid-phase endocytosis. Selectivity for the osteoclast requires no targeting ligand: it follows from the cell being the only one that dissolves the reservoir.
It jams the enzyme far harder than alendronate does
Inside the cell it blocks the same enzyme, and blocks it about a hundred times more tightly. In the body this advantage disappears, because so little drug gets to the cell in the first place.
──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
IC50 against recombinant human farnesyl diphosphate synthase is 3.9 nM, against 460 nM for alendronate in the same assay. The nitrogen of the pyridine ring occupies the allylic site and mimics the carbocation intermediate of the enzyme’s natural reaction, which is why ring position matters and why non-nitrogen bisphosphonates such as clodronate do not inhibit this enzyme at all.
Prenylation fails and the resorbing cell loses its machinery
Several of the cell’s internal controllers need a fatty tag to sit on the membrane. Without the tag they float free, the cell loses its grip on bone and its digestive surface, and demolition stops.
╌╌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
Depletion of farnesyl and geranylgeranyl diphosphate leaves Rab, Rho and Rac GTPases unprenylated, breaking vesicular trafficking and cytoskeletal organisation. The osteoclast stays attached but loses its ruffled border, and unprenylated substrate accumulation drives apoptosis of the cell.
Fewer fractures — in bone-driven risk, not in fall-driven risk
Where the reason a hip breaks is that the bone is weak, this works. Where the reason is that the person falls a lot, the trial showed no benefit at all.
──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
Hip fracture fell from 3.2% to 1.9% in 5445 women aged 70 to 79 selected on femoral-neck T-score, and from 5.1% to 4.2% with P=0.35 in 3886 women aged 80 and over selected largely on non-skeletal risk factors. Suppressing resorption changes the bone term in fracture risk and leaves the fall term untouched.
No suggested links are held for this record, so nothing is hidden from this path.
What we know
The record describes 6 steps from taking it to an effect in a person.
How we know it
Each step names the study behind it in the technical detail beside it.
What this does not prove
A change inside the body is a reason to look. It is not a result in a person.
Why it matters
A reader can see exactly where the chain stops being measured in people.
What we still do not know
No reviewed claim binds any of these steps to a named population.
What is missing or unclear◇Read from sources, not yet reviewed
Were people like you studied?
RNAWiki cannot tell whether a study fits you. It can show who was in it, and where the result stops carrying.
Who was studied
People similar to this profile were included.
Postmenopausal women with or at risk of osteoporosis, men with osteoporosis, people on long-term glucocorticoids, and people with Paget disease of bone.
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: “Risedronate is not indicated for use in pediatric patients.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
On older people, the label states: “Of the patients receiving risedronate in postmenopausal osteoporosis studies [see Clinical Studies (14) ] , 47% were between 65 and 75 years of age, and 17% were over 75.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
On people who are pregnant, the label states: “Risk Summary Available data on the use of risedronate in pregnant women are insufficient to inform a drug-associated risk of adverse maternal or fetal outcomes.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
On people who are breastfeeding, the label states: “Risk Summary There are no data on the presence of risedronate in human milk, the effects on the breastfed infant, or the effects on milk production.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
On people with reduced liver function, the label states: “No studies have been performed to assess risedronate’s safety or efficacy in patients with hepatic impairment.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
On people with reduced kidney function, the label states: “Risedronate is not recommended for use in patients with severe renal impairment (creatinine clearance less than 30 mL/min) because of lack of clinical experience.”
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
Where the result stopped carrying
The hip-fracture endpoint was missed in the 3886 women aged 80 and over, 4.2% against 5.1%, P=0.35
Non-vertebral fracture in VERT-MN reached only 33% with P=0.06
Two Cochrane reviews, fourteen years apart, found the primary-prevention question unanswerable: four short trials, 989 women, zero clinical vertebral and zero hip fractures
The delayed-release formulation, built to solve the fasting problem, carries an osteoporosis efficacy claim based on one year of clinical data by the label’s own statement
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
Prescription only
❝ 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 immediate-release tablet and oral delayed-release tablet
✎ Source-linked record
Where this came from
A person wrote this into the record with the study named beside it. No reviewer has signed it off.
The form and route recorded on this substance.
No source is stored against this line.
Who oversees it
RNAWiki has not recorded a supervision or regulatory status for this substance.
❝ Quoted from a source
Where this came from
Copied from a source RNAWiki stored, with the source named.
No register row and no identity class settled the question.
No source is stored against this line.
What is in the pack
The immediate-release tablet is taken fasting with plain water and the patient stays upright. The delayed-release tablet uses an enteric coat with a chelating agent so it can be taken immediately after breakfast, which is the only real formulation innovation in the oral bisphosphonates.
✎ 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
No boxed warning. Upper gastrointestinal irritation, oesophagitis and oesophageal ulceration are the characteristic label warnings for the immediate-release tablet. Osteonecrosis of the jaw and atypical subtrochanteric or diaphyseal femoral fracture are class warnings established after approval. In the 2022 Cochrane synthesis, withdrawals due to adverse events were 16.9% on risedronate against 17.2% on control across eight trials in 9529 women (high certainty), and serious adverse events were 29.2% in both groups across six trials in 9435 women (moderate certainty).
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 immediate-release tablet and oral delayed-release tablet
✎ 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 delayed-release tablet uses an enteric coat with a chelating agent so it can be taken immediately after breakfast, which is the only real formulation innovation in the oral bisphosphonates.
✎ 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
35 products list this as an active ingredient in the United States drug directory. 26 of them contain it and nothing else.
FDA National Drug Code directory · 65862-518 · read 2026-08-29
They are sold as powder, tablet, delayed release and tablet, film coated, taken oral.
FDA National Drug Code directory · 65862-518 · read 2026-08-29
The regulator's established pharmacologic class for it is bisphosphonate [epc] and diphosphonates [cs].
FDA National Drug Code directory · 65862-518 · read 2026-08-29
13 published labels name it as an active ingredient. 9 of them describe this substance alone, which is where its own label text on this page comes from.
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-29
Those labels are classed as human prescription drug.
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-29
Risedronate Sodium is oral at 3 DOSAGE FORMS AND STRENGTHS 5 mg yellow colored, circular, beveled edge, film-coated biconvex tablets debossed with ‘X’ on one side and ‘61’ on the other side. 30 mg white to off-white, circular, film-coated biconvex t…, recorded as fda label in effect 2026-02-11 in the United States.
US prescribing information · 89896dfe-f69d-4cb3-bb71-7a7c611071fa · read 2026-08-30
Recorded price in US: 1.49758–12.81755 USD per one unit as the pricing file counts it — a tablet, capsule, patch or single item, across 21 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.
RNAWiki could not confidently classify this substance, so no self-experiment plan is offered.
Questions worth asking
Which of the trials of Risedronic acid 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 a hundredfold advantage at the enzyme makes it a hundredfold, or any amount, better as a drug in people
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 fracture reduction demonstrated in osteoporotic populations extends to lower-risk women — Cochrane found the primary-prevention effects not estimable in 2008 and again in 2022
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 pooling forty-three trials produces a robust answer, when the reviewers report none of them was at low risk of bias across all seven domains
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 reducing bone resorption addresses fracture risk generally, when the same trial showed nothing in women whose risk came from falling
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 Risedronic acid 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.
Hip fracture was the primary endpoint, and it was met in the osteoporotic group
In plain words
Nine thousand elderly women were randomised, and the trial declared hip fracture as the thing it was measuring. In the group selected because their bone density was low, hip fractures fell from about three in a hundred to about two in a hundred.
What was measured
Hip fracture at three years, 1.9% against 3.2% in the osteoporotic 70-79 group, RR 0.6 (95% CI 0.4 to 0.9)
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The Hip Intervention Program studied 5445 women aged 70 to 79 with osteoporosis by femoral-neck T-score and 3886 women aged 80 or over selected mainly on non-skeletal risk factors such as poor gait or a propensity to fall, randomised to risedronate 2.5 or 5.0 mg daily or placebo for three years. Across all women, hip fracture occurred in 2.8% on risedronate against 3.9% on placebo, relative risk 0.7 (95% CI 0.6 to 0.9, P=0.02). In the 70-to-79 osteoporosis group it was 1.9% against 3.2%, relative risk 0.6 (95% CI 0.4 to 0.9, P=0.009).
Written into the record, not signed off as a reviewed claim
In the women selected on falls risk rather than bone density, it did nothing
In plain words
The same trial enrolled a second group: women aged 80 and over chosen mainly because they were likely to fall, not because a scan showed thin bone. In that group the drug did not reduce hip fractures at all.
What was measured
Hip fracture 4.2% against 5.1% in women aged 80 and over, P=0.35
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
Among the 3886 women aged at least 80, selected on at least one non-skeletal risk factor for hip fracture or on low femoral-neck density, hip fracture occurred in 4.2% on risedronate against 5.1% on placebo, P=0.35. The contrast with the younger osteoporotic group is the finding: a drug that suppresses bone resorption changes the outcome in people whose fracture risk is driven by bone, and does not change it in people whose fracture risk is driven by falling. This is a mechanism result, not a dosing one, and it is the strongest argument in the file against treating fracture risk as a single quantity.
Written into the record, not signed off as a reviewed claim
Cochrane finds no demonstrated benefit in primary prevention, twice
In plain words
When all the randomised evidence is pooled, the drug clearly reduces fractures in women who already have osteoporosis. In women who do not, there is no demonstrated effect — and after fourteen years and a full review update, there is still no demonstrated effect.
What was measured
Primary prevention: zero clinical vertebral and zero hip fractures across four trials in 989 women, effects not estimable
Effect estimate
No reviewed effect estimate exists for this record.
Limits
This entry records a failure.
From the source
The 2008 Cochrane review of seven trials in 14,049 women reported no statistically significant effect of risedronate 5 mg/day on vertebral or non-vertebral fracture in primary prevention, against a 39% relative reduction in vertebral fracture (RR 0.61, 95% CI 0.50 to 0.76), 20% in non-vertebral (RR 0.80, 0.72 to 0.90) and 26% in hip fracture (RR 0.74, 0.59 to 0.94) in secondary prevention. The 2022 update screened 43 eligible trials and synthesised 33 in 27,348 participants. Its primary-prevention evidence came from four short trials in 989 lower-risk women, with zero clinical vertebral and zero hip fractures reported, making those effects not estimable, and wrist fracture RR 0.48 with a confidence interval of 0.03 to 7.50. The authors graded primary-prevention evidence low to very low certainty. Secondary prevention was confirmed: non-vertebral RR 0.80 (0.72 to 0.90, moderate certainty) and hip RR 0.73 (0.56 to 0.94, low certainty).
Written into the record, not signed off as a reviewed claim
A hundredfold potency advantage on the enzyme, and no advantage in people
In plain words
On the isolated enzyme, risedronate is about a hundred times stronger than alendronate. In patients this makes no measurable difference, because how much drug reaches the enzyme is decided by absorption and by how tightly the drug grips bone mineral, not by how tightly it grips the enzyme.
What was measured
That a hundredfold advantage in enzyme inhibition means a stronger drug — bioavailability and mineral binding sit between the two numbers and no fracture trial has tested the implication
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
In a single experiment on recombinant human farnesyl diphosphate synthase, IC50 values were 3.9 nM for risedronate, 460 nM for alendronate and 500 nM for pamidronate. The clinical doses do not follow that ratio, and no adequately powered head-to-head trial has shown a fracture difference between the two oral drugs. The reason is that potency at the enzyme is only one of three terms: oral bioavailability is 0.63% for risedronate and 0.64% for alendronate, and the two differ in affinity for hydroxyapatite, which governs how much drug is retained at the resorption surface and how long it stays there. A page that reported only the enzyme number would imply a hundredfold better drug.
Written into the record, not signed off as a reviewed claim
Two vertebral-fracture trials on two continents, both positive
In plain words
Two separate three-year trials, one in North America and one in Europe and Australia, both enrolled women who had already fractured a vertebra. Spinal fractures fell by 41% in the first and 49% in the second.
What was measured
New vertebral fracture over three years: 11.3% against 16.3% in VERT-NA; 49% relative reduction in VERT-MN
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
VERT-NA randomised 2458 postmenopausal women under 85 with at least one vertebral fracture at 110 North American centres. Risedronate 5 mg reduced new vertebral fracture by 41% over three years (11.3% against 16.3%, 95% CI 18% to 58%, P=0.003) and by 65% in the first year alone (2.4% against 6.4%, P<0.001); non-vertebral fracture fell 39% (5.2% against 8.4%, 95% CI 6% to 61%, P=0.02). VERT-MN randomised 1226 women with two or more prevalent vertebral fractures at 80 centres in Europe and Australia, and reported a 49% reduction over three years (P<0.001) with 61% in the first year (P=0.001); non-vertebral fracture fell 33% but did not reach significance (P=0.06). The 2.5 mg arm was discontinued by protocol amendment in both trials.
Written into the record, not signed off as a reviewed claim
None of the pooled trials was at low risk of bias in every domain
In plain words
The reviewers who pooled forty-three trials reported that not one of them was well conducted on every measure they checked. Only a quarter described properly how patients were assigned to groups.
What was measured
That a positive pooled estimate from many trials is stronger than one good trial — pooling many trials that share a bias does not remove the bias, and the reviewers say so explicitly
Effect estimate
No reviewed effect estimate exists for this record.
Limits
See the technical detail.
From the source
The 2022 Cochrane update states that selection bias was the most frequent concern, that only 24% of studies described appropriate methods for both sequence generation and allocation concealment, that 50% of studies reporting benefit outcomes and 39% reporting harm outcomes were at high risk of bias, and that none of the studies included in the quantitative syntheses was judged at low risk of bias in all seven domains. The review also notes it was updated without industry sponsorship, which the earlier version was not in a position to say of its constituent trials.
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What is not here
7 questions this page could not answer
These sections were prepared and left out because there was nothing to put in them. They are listed rather than hidden, so the gaps in this record are visible.
What was measured, goal by goal — found nothing in the sources checked.
How close this is to real life — found nothing in the sources checked.
Felt, measured, or meaningful — found nothing in the sources checked.
How long anything takes — found nothing in the sources checked.
What it may clash with — found nothing in the sources checked.
Other ways to the same goal — found nothing in the sources checked.
What changed on this page — found nothing in the sources checked.
The record as stored
The full record, for auditing
Everything above is built from what is below. This layer keeps the technical vocabulary, record identifiers and every stored row, so a reader who wants to check the page can.
The older medicine-wide conclusion held in this record
Written for a clinical reader, and about the medicine as a whole rather than about one indication, population and set of trials. RNAWiki does not treat it as a programme conclusion and no reviewer has signed it off in that form. It is here word for word because it is what the record holds.
A pyridine bisphosphonate that inhibits the osteoclast’s farnesyl diphosphate synthase at 3.9 nanomolar — a hundred times more potently than alendronate on the isolated enzyme, without being a better drug — and that cut hip fractures from 3.2% to 1.9% in 5445 women aged 70 to 79 with osteoporosis while doing nothing measurable, 4.2% against 5.1%, in 3886 women aged 80 and over selected on falls risk instead of bone density.
Recorded evidence blocks (9)
Q1
On the Risedronic acid label: indicated for what?
"Risedronate sodium tablets are a bisphosphonate indicated for: Treatment and prevention of postmenopausal osteoporosis ( 1.1 ) Treatment to increase bone mass in men with osteoporosis ( 1.2 ) Treatment and prevention of glucocorticoid-induced osteoporosis ( 1.3 ) Treatment of Paget’s disease ( 1.4 ) Limitations of Use…": indications and usage on Risedronic acid's label. DailyMed label · dddcd321-4d2e-4643-bf3c-7b752b33ba39 · 2026-03-30
Q2
87 registered trials of Risedronic acid — at which phases?
Registered studies posting no result
50 of 87
87 registered studies of Risedronic acid: 36 phase3, 28 phase4, 9 phase2, 6 na or unstated, 6 phase1, 5 na. CLINICALTRIALS_SNAPSHOT · 2026-09-01
315 with a PubMed record
Show the evidence
phase3
36
phase4
28
phase2
9
na or unstated
6
phase1
6
na
5
5 more recorded rows
completed
77
terminated
5
recruiting
2
withdrawn
2
unknown
1
recorded 2026-09-01 · last checked 2026-09-04
Q3
4 of Risedronic acid's trials stopped: accrual/recruitment, other?
"Terminated due to low accrual"; 4 of 87 registered studies
Show the evidence
Trial
NCT00216060
terminated; "Terminated due to low accrual"
NCT00544180
terminated; "The trial was terminated due to lack of compliance with GCP regulations."
NCT00594334
withdrawn; "Never started"
NCT02744482
terminated; "lack of patients"
recorded 2026-09-01 · last checked 2026-09-04
Q4
Human studies of Risedronic acid used Risedronate 35 mg — over how long?
Human studies of Risedronic acid used "Risedronate 35 mg". ClinicalTrials.gov · 2026-09-01
5 recorded entries; human; also "- Other name : Risenex M(risedronate 150mg and cholecalciferol 30,000 IU combined)", "Other name : Actonel(Risedronate 150mg)", "Actonel 17.5mg Tablets"
Show the evidence
human
NCT00092014
Risedronate 35 mg
NCT01806792
- Other name : Risenex M(risedronate 150mg and cholecalciferol 30,000 IU combined)
NCT01806792
Other name : Actonel(Risedronate 150mg)
NCT02106455
Actonel 17.5mg Tablets
NCT03411902
Risedronate Sodium 150 MG
recorded 2026-09-01 · last checked 2026-09-04
Q5
Risedronic acid's half-life is 561 hours — which schedules were studied?
561 hours, the half-life Risedronic acid's label states: "In osteopenic postmenopausal women, the terminal exponential half-life was 561 hours, mean renal clearance was 52 mL/min (CV = 25%), and mean total clearance was 73 mL/min (CV = 15%)." DailyMed label · dddcd321-4d2e-4643-bf3c-7b752b33ba39 · 2026-03-30
tmax 1 hour; bioavailability 0.63 %.
Show the evidence
half lifepharmacokinetics
561 hours; In osteopenic postmenopausal women, the terminal exponential half-life was 561 hours, mean renal clearance was 52 mL/min (CV = 25%), and mean total clearance was 73 mL/min (CV = 15%).
tmaxpharmacokinetics
1 hour; Absorption Based on simultaneous modeling of serum and urine data, peak absorption after an oral dose is achieved at approximately 1 hour (T max ) and occurs throughout the upper gastrointestinal tract.
bioavailabilitypharmacokinetics
0.63 %; Mean absolute oral bioavailability of the 30 mg tablet is 0.63% (90% CI: 0.54% to 0.75%) and is comparable to a solution.
metabolismpharmacokinetics
Metabolism There is no evidence of systemic metabolism of risedronate.
recorded 2026-03-30 · last checked 2026-09-04
Q6
Which 38 trials of Risedronic acid posted no result?
Posted no result
38 of 38 completed trials
Registrations
NCT00351091, NCT00577850, NCT00092014, NCT00402441, NCT00549068 and NCT00616694, and 32 more
Completion dates
oldest 2003-06; newest 2022-02-26
Show the evidence
Trial
NCT00351091
2003-06
NCT00577850
2004-02
NCT00092014
2004-04-01
NCT00402441
2004-06
NCT00549068
2004-11
NCT00616694
2004-12
14 further recorded trials
NCT00353080
2005-04
NCT00577837
2005-06
NCT00150696
2005-11
NCT00577421
2006-01
NCT00632216
2006-05
NCT00118508
2006-07
NCT00837746
2006-10
NCT00130403
2007-03
NCT00358176
2007-03
NCT00372372
2007-04
NCT01882400
2007-09
NCT00082277
2007-10
NCT00567606
2007-12-01
NCT00755872
2008-02
Q7
At the median, Risedronic acid's trials enrolled 148 people — anything larger?
Median enrolment
148
Largest enrolment
684815
Registered trials counted
85
Q8
What do 3306 spontaneous reports say about Risedronic acid — 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.
Risedronic acid appears in spontaneous reports to regulators. Across the 10 most-reported reaction terms, 3306 reaction mentions were counted: femur fracture 535; arthralgia 497; fall 444; pain in extremity 320. FAERS via Open Targets · CHEMBL1654 · 2026-06-24
Show the evidence
femur fracture
535
arthralgia
497
fall
444
pain in extremity
320
pain
289
nausea
275
4 more recorded rows
gastrooesophageal reflux disease
255
drug hypersensitivity
249
osteoporosis
226
osteonecrosis of jaw
216
recorded 2026-06-24 · last checked 2026-09-04
Q9
Which 10 reactions does Risedronic acid's label not list?
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
✓ canonical metadata passed: slug and display name present
✓ no raw internal fields: enforced by the copy-contract test over the rendered page
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