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Causality: well established
Causality assessment · Causality: well established
Zonisamide and Nephrolithiasis: is the FAERS signal real?
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.
Zonisamide ↔ Nephrolithiasis
n=189 co-reports · PRR 5.9 · ROR 6.0
Zonisamide is a sulfonamide antiepileptic; the sulfonamide group inhibits carbonic anhydrase and alkalinises urine, promoting calcium phosphate kidney stones (189 co-reports, PRR 5.9), along with metabolic acidosis and hypohidrosis. The label advises adequate hydration and warns of kidney-stone risk, which is higher in patients with a history of stones.
Regulatory basis: zonisamide (Zonegran) prescribing information — nephrolithiasis and metabolic acidosis.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Stones develop over months |
| Strength | met | PRR 5.9, moderate |
| Consistency | met | Reproduced in case series |
| Specificity | partial | Shared with other sulfonamides |
| Biological gradient | partial | Risk rises with predisposing factors |
| Plausibility | met | Carbonic-anhydrase inhibition and urinary alkalinisation |
| Coherence | met | Fits the pharmacology |
| Experiment | n/a | Not a trial endpoint |
| Analogy | met | Analogous to topiramate and acetazolamide stones |
This table is this page's own qualitative read of the literature cited above, not an automated or citation-gated assessment — see the note at the bottom of this page.
✗ No ClinicalTrials.gov results-posting trial in the top search hits for zonisamide captured nephrolithiasis as a tracked adverse event in a usable structure. Epilepsy trials of zonisamide did not report nephrolithiasis as a structured coded adverse event.