Causality assessment · Causality: well established

Daptomycin and Myopathy / rhabdomyolysis: is the FAERS signal real?

n=370 co-reports · PRR 20.5 · ROR 21.3

Daptomycin side-effect profile All assessments See in the full list

A written Bradford Hill assessment of one drug–event pair. The grade is a judgement about the signal, not a statement that this drug causes this event in any one person; FAERS counts are reports, not rates.

Causality: well established

Daptomycin ↔ Myopathy / rhabdomyolysis

n=370 co-reports · PRR 20.5 · ROR 21.3 Creatine kinase increased (related term): n=331 · PRR 26.2

Daptomycin, a lipopeptide antibiotic used for resistant Gram-positive infections, can injure skeletal muscle, producing rises in creatine kinase that occasionally progress to rhabdomyolysis. Because of this, the labelling recommends checking creatine kinase at baseline and periodically during therapy, and stopping the drug if levels rise significantly. The effect is dose-related and can be worsened by statin co-therapy. The 370 co-reports (PRR 20.5) reflect a genuine, monitorable toxicity.

Regulatory basis: daptomycin prescribing information (myopathy and creatine-kinase monitoring).

Bradford Hill viewpoint	Status	Note
Temporality (necessary)	met	Muscle injury appears during therapy and resolves after the drug is stopped
Strength	met	PRR 20 on a moderate co-report count, with a parallel CK-increase signal
Consistency	met	Reproduced in trials that measured creatine kinase
Specificity	met	A recognised daptomycin toxicity, less typical of other antibiotics
Biological gradient	partial	Dose-related and worse with statin co-therapy
Plausibility	met	Direct injury to skeletal muscle is the proposed mechanism
Coherence	met	Coheres with the labelled CK-monitoring recommendation
Experiment	met	A randomized registration trial recorded CK rises only on daptomycin
Analogy	met	Analogous to myopathy from statins and other myotoxic drugs

This page's own qualitative read, not an automated/citation-gated assessment.

✓ Trial evidence found — China Registration Study in Patients With Skin Infections (NCT00772447), N=264

Term (as recorded)	Daptomycin (n=131)	Vancomycin, or Vancomycin Switch to Cloxacillin (n=133)
Blood Creatine Phosphokinase Increased — Investigations	4	0

Rises in creatine kinase were recorded only on daptomycin (4 of 131 patients) and in none of the vancomycin-treated patients in this randomized registration trial — direct trial-level support for the muscle-injury signal that prompts routine CK monitoring during daptomycin therapy. View on ClinicalTrials.gov →