Naltrexone and Drug withdrawal syndrome: is the FAERS signal real?
Naltrexone ↔ Drug withdrawal syndrome
Naltrexone is an opioid-receptor antagonist; in opioid-dependent patients it precipitates an acute, severe withdrawal syndrome if given before the patient is fully detoxified (595 co-reports, PRR 9.8), with agitation, abdominal cramps, vomiting, and piloerection. The label requires a period of abstinence (commonly 7–10 days) before the first dose to avoid triggering this reaction.
Regulatory basis: naltrexone prescribing information — precipitation of opioid withdrawal; required abstinence period.
| Bradford Hill viewpoint | Status | Note |
|---|---|---|
| Temporality (necessary) | met | Immediate withdrawal on dosing |
| Strength | met | PRR 9.8, large |
| Consistency | met | Reproduced across clinical experience |
| Specificity | met | Specific to opioid-dependent patients |
| Biological gradient | met | Related to opioid load |
| Plausibility | met | Direct opioid-receptor blockade mechanism |
| Coherence | met | Fits the mechanism exactly |
| Experiment | met | Clinical studies confirm it |
| Analogy | met | Analogous to naloxone-precipitated withdrawal |
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.
✓ Trial evidence found — ALK21-003: Study of Medisorb® Naltrexone (VIVITROL®) in Alcohol-Dependent Adults (NCT01218958)
| Adverse event | Medisorb Naltrexone 190 mg (n=210) · Medisorb Naltrexone 380 mg (n=205) · Placebo Groups (Pooled) (n=209) | ||
|---|---|---|---|
| Alcohol withdrawal syndrome | 1/210 | 0/205 | 0/209 |
Post-marketing signal terms appear in this trial's posted adverse-event tables; per-arm counts shown as affected/at-risk. View on ClinicalTrials.gov →