Casimersen side effects: what 851 FDA adverse event reports show

Casimersen · Amondys 45 · 9 reaction terms · 703 drug–reaction co-reports · data 2026-09-14

Drug class

Antisense Oligonucleotide

FDA label (Established Pharmacologic Class) · compare the class

Brand names

Amondys 45

openFDA label

Who reports

851 reports · 19% serious · 10 with death outcome · 0% female

openFDA FAERS counts, all years, deduplication not applied

Used for

AMONDYS 45 is indicated for the treatment of Duchenne muscular dystrophy (DMD) in patients who have a confirmed mutation of the DMD gene that is amenable to exon 45 skipping. This indication is approved under accelerated approval based on an increase in dystrophin production in skeletal muscle observed in patients treated with AMONDYS 45 .

FDA label, Indications and Usage

What it is

AMONDYS 45 (casimersen) injection is a sterile, aqueous, preservative-free, concentrated solution for dilution prior to intravenous administration. AMONDYS 45 is a clear to slightly opalescent, colorless liquid and may contain trace amounts of small, white to off-white amorphous particles.

FDA label, Description section

Boxed warning

None in the current label

How to read this page. FAERS is a spontaneous-reporting system: counts are not incidence rates and a signal is not proof of causation. Each reaction below is run through an automated screen — is the term in the FDA label (known), in the indications (the disease being treated), an administrative/coding term, or none of these (unlabeled)? That screen is mechanical text matching, not a causality assessment. The 30 hand-written Bradford Hill assessments are on the causality assessment page. Not medical advice.

Causality screen of the 9 strongest signals

Reporting / coding artifact 6Not in label — unassessed 3

What the badges mean

Reporting / coding artifact An administrative, monitoring or exposure term (product issue, off-label use, 'test normal', overdose...). Not a biological reaction; a high PRR here reflects how reports are coded.
Not in label — unassessed Not found in the label text, not an artifact pattern. This is a genuine candidate for a formal causality assessment (Bradford Hill / WHO-UMC); it has NOT had one here.

Strongest disproportionality signals

Flagged terms (PRR ≥ 2, χ² ≥ 4, n ≥ 10), ranked by PRR; infinite PRRs (no comparator reports) excluded. The EBGM column is a second, shrinkage-based estimate (MGPS) with its 5th percentile EB05 and the BCPNN IC025; a pair flagged by PRR alone is marked PRR-only and should be read as fragile. The strata column recomputes the PRR on serious reports only and flags pairs whose reports are unusually skewed by sex or come mostly from consumers rather than clinicians. 0 further terms are in the interactive explorer. Reaction links open the term's cross-drug page.

Show: hide coding/lab/outcome terms hide indication terms unlabeled only hide PRR-only

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Poor venous access	102	245.9 204.8–295.3ROR 279.3 · χ² 24,401 / p <1e-300	232.9 EB05 197.3 · IC025 +6.5 3/3 methods agree	Not in label — unassessed	serious n=7 · 92% clinician	no trial data cached
Intentional dose omission	74	66.9 53.8–83.1ROR 73.1 · χ² 4,728 / p <1e-300	65.6 EB05 54.0 · IC025 +5.1 3/3 methods agree	Reporting / coding artifact	95% clinician	no trial data cached
No adverse event	166	23.1 20.1–26.5ROR 28.4 · χ² 3,511 / p <1e-300	23.0 EB05 20.2 · IC025 +4.2 3/3 methods agree	Reporting / coding artifact	95% clinician	no trial data cached
Product dose omission issue	257	22.3 20.1–24.7ROR 31.5 · χ² 5,264 / p <1e-300	22.2 EB05 20.0 · IC025 +4.2 3/3 methods agree	Reporting / coding artifact	serious PRR 4.1	no trial data cached
Device issue	76	21.5 17.3–26.6ROR 23.5 · χ² 1,468 / p <1e-300	21.4 EB05 17.6 · IC025 +3.9 3/3 methods agree	Reporting / coding artifact	serious PRR 4.1	no trial data cached
Device occlusion	6	10.6 4.8–23.6ROR 10.7 · χ² 43 / p 2e-11	7.3 EB05 3.2 · IC025 +1.2 3/3 methods agree	Reporting / coding artifact	serious n=1	no trial data cached
Lower limb fracture	8	10.3 5.2–20.6ROR 10.4 · χ² 58 / p 1e-14	7.8 EB05 3.8 · IC025 +1.5 3/3 methods agree	Not in label — unassessed	serious PRR 22.0	no trial data cached
Insurance issue	5	8.3 3.5–19.9ROR 8.3 · χ² 25 / p 3e-7	5.3 EB05 2.4 · IC025 +0.8 3/3 methods agree	Not in label — unassessed	–	no trial data cached
Device dislocation	9	5.1 2.7–9.8ROR 5.2 · χ² 26 / p 2e-7	4.2 EB05 2.4 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	–	no trial data cached

Trial evidence (ClinicalTrials.gov)

Trial cross-check not yet run for this drug (ClinicalTrials.gov pull covers the 800 most-reported drugs first).

Most frequently reported reactions

By raw co-report count, regardless of disproportionality. Common terms here are often the illness itself or generic outcomes.

Reaction	Reports	PRR 95% CI · ROR · χ²/p	EBGM EB05 · IC025	Label screen	Serious-only & strata	Trial cross-check
Product dose omission issue	257	22.3 20.1–24.7ROR 31.5 · χ² 5,264 / p <1e-300	22.2 EB05 20.0 · IC025 +4.2 3/3 methods agree	Reporting / coding artifact	serious PRR 4.1	no trial data cached
No adverse event	166	23.1 20.1–26.5ROR 28.4 · χ² 3,511 / p <1e-300	23.0 EB05 20.2 · IC025 +4.2 3/3 methods agree	Reporting / coding artifact	95% clinician	no trial data cached
Poor venous access	102	245.9 204.8–295.3ROR 279.3 · χ² 24,401 / p <1e-300	232.9 EB05 197.3 · IC025 +6.5 3/3 methods agree	Not in label — unassessed	serious n=7 · 92% clinician	no trial data cached
Device issue	76	21.5 17.3–26.6ROR 23.5 · χ² 1,468 / p <1e-300	21.4 EB05 17.6 · IC025 +3.9 3/3 methods agree	Reporting / coding artifact	serious PRR 4.1	no trial data cached
Intentional dose omission	74	66.9 53.8–83.1ROR 73.1 · χ² 4,728 / p <1e-300	65.6 EB05 54.0 · IC025 +5.1 3/3 methods agree	Reporting / coding artifact	95% clinician	no trial data cached
Device dislocation	9	5.1 2.7–9.8ROR 5.2 · χ² 26 / p 2e-7	4.2 EB05 2.4 · IC025 +0.9 3/3 methods agree	Reporting / coding artifact	–	no trial data cached
Lower limb fracture	8	10.3 5.2–20.6ROR 10.4 · χ² 58 / p 1e-14	7.8 EB05 3.8 · IC025 +1.5 3/3 methods agree	Not in label — unassessed	serious PRR 22.0	no trial data cached
Device occlusion	6	10.6 4.8–23.6ROR 10.7 · χ² 43 / p 2e-11	7.3 EB05 3.2 · IC025 +1.2 3/3 methods agree	Reporting / coding artifact	serious n=1	no trial data cached
Insurance issue	5	8.3 3.5–19.9ROR 8.3 · χ² 25 / p 3e-7	5.3 EB05 2.4 · IC025 +0.8 3/3 methods agree	Not in label — unassessed	–	no trial data cached

Unlabeled candidate signals

These flagged terms were not found in the FDA label text and do not match an artifact pattern. They are the pairs that would merit a structured assessment (temporality, dose-response, biological plausibility, consistency across databases, trial or cohort evidence). The screen has not done that; string-matching misses label wording, and a strong PRR can still be stimulated reporting, co-medication, or the disease itself.

Poor venous access — n=102, PRR 245.9

Want to assess one of these properly? The runbook describes the Bradford Hill / trial-evidence workflow used on the assessment page, and handoff_top1000_signals.csv lists the strongest unassessed pairs across all drugs.

Common questions

What are the most reported side effects of Casimersen?

In FDA FAERS, the most frequently co-reported reaction terms for Casimersen are poor venous access, lower limb fracture, insurance issue. These are report counts, not rates: FAERS has no denominator, reporting is voluntary and uneven, and a term can be reported because of the illness being treated rather than the drug.

Does Casimersen have an FDA boxed warning?

No. The FDA label retrieved for Casimersen has no boxed warning; see the label's Warnings and Precautions for the recognised risks.

Do FAERS signals prove that Casimersen causes these side effects?

No. A disproportionality signal (PRR, ROR) means a reaction is reported more often with this drug than with others in the database. That can reflect a real effect, but also the disease being treated, stimulated reporting after news or litigation, co-medications, or how reports are coded. Causality needs temporality, dose-response, biological plausibility, consistency across data sources and, ideally, trial or cohort evidence. This page screens each term against the FDA label and ClinicalTrials.gov results; it does not establish causation.

Sources & methods

FDA label via openFDA (set ID e9e5fd44-eeda-4580-bba1-a734828bbcc3, effective 20260109; matched on openfda.generic_name.exact:"CASIMERSEN")
Bayesian shrinkage measures computed offline over all 1,317,300 cached pairs: BCPNN information component (IC, with Norén closed-form IC025) and MGPS empirical-Bayes geometric mean (EBGM, EB05) with a two-component gamma prior fitted by maximum marginal likelihood (α₁=0.57, β₁=0.02, α₂=1.42, β₂=0.70, w=0.17); unstratified
FAERS pair statistics from the OpenPV build of 2026-09-14 (openFDA count= aggregation, field patient.drug.openfda.generic_name.exact, 9 reaction terms, min 3 co-reports); PRR/ROR with 95% CI, chi-square with Yates correction
Serious-only and stratified counts (serious:1, patient.patientsex, primarysource.qualification) from openFDA count queries; serious-only PRR uses the drug serious report total and the term global serious total (N_serious=11,882,979); strata shown only when n ≥ 20
Seriousness and sex counts from openFDA count=serious, patient.patientsex, seriousnessdeath

Page generated 2026-10-08. Label and PubChem text are retrieved automatically and may lag the current label; always check the current prescribing information. OpenPV is a beta research tool of the Open Source Medicine Foundation.