Classifies and documents adverse drug reactions with causality assessment (Naranjo) and reporting. Use when evaluating ADRs, assessing drug causality, or reporting adverse events.
Classifies and documents adverse drug reactions with causality assessment using the Naranjo algorithm and structured reporting through FDA MedWatch and institutional systems.
Adverse drug reactions (ADRs) are the fourth leading cause of death in the United States, causing an estimated 100,000 deaths and 2.2 million serious reactions annually. ADRs account for approximately 6.5% of all hospital admissions and prolong hospital stays by an average of 2 days. Despite FDA post-marketing surveillance requirements, fewer than 10% of serious ADRs are reported to MedWatch, creating a significant pharmacovigilance gap.
Pharmacists are uniquely positioned to detect, assess, manage, and report ADRs. Causality assessment using validated tools—the Naranjo Adverse Drug Reaction Probability Scale being the most widely used—is essential to distinguish true drug-caused reactions from coincidental events, disease progression, or drug interactions. The WHO-UMC causality system and the FDA Adverse Event Reporting System (FAERS) depend on structured reports from healthcare professionals. Institutions are required by the Joint Commission to have ADR reporting and monitoring programs, and the pharmacist typically manages this process.
By mechanism (Rawlins-Thompson classification):
| Type | Name | Characteristics | Examples |
|---|---|---|---|
| A | Augmented | Dose-dependent, predictable, related to pharmacologic action | Hypoglycemia from insulin, bleeding from warfarin, bradycardia from beta-blockers |
| B | Bizarre | Dose-independent, unpredictable, immunologic or idiosyncratic | Anaphylaxis from penicillin, Stevens-Johnson syndrome, malignant hyperthermia |
| C | Chronic | Dose and time-dependent, cumulative | Osteoporosis from corticosteroids, nephrotoxicity from lithium |
| D | Delayed | Time-dependent, appear after long latency | Carcinogenesis, teratogenicity (thalidomide) |
| E | End of use | Withdrawal reactions | Rebound hypertension from clonidine, benzodiazepine withdrawal seizures |
| F | Failure | Unexpected therapeutic failure, often dose-related | Oral contraceptive failure with enzyme inducers |
By severity (CTCAE v5.0 grading):
Score each question and sum for total probability:
| # | Question | Yes | No | Unknown |
|---|---|---|---|---|
| 1 | Are there previous conclusive reports on this reaction? | +1 | 0 | 0 |
| 2 | Did the adverse event appear after the suspected drug was administered? | +2 | -1 | 0 |
| 3 | Did the adverse reaction improve when the drug was discontinued or a specific antagonist was administered? | +1 | 0 | 0 |
| 4 | Did the adverse reaction reappear when the drug was readministered? | +2 | -1 | 0 |
| 5 | Are there alternative causes (other than the drug) that could on their own have caused the reaction? | -1 | +2 | 0 |
| 6 | Did the reaction reappear when a placebo was given? | -1 | +1 | 0 |
| 7 | Was the drug detected in the blood (or other fluids) in concentrations known to be toxic? | +1 | 0 | 0 |
| 8 | Was the reaction more severe when the dose was increased, or less severe when the dose was decreased? | +1 | 0 | 0 |
| 9 | Did the patient have a similar reaction to the same or similar drugs in any previous exposure? | +1 | 0 | 0 |
| 10 | Was the adverse event confirmed by any objective evidence? | +1 | 0 | 0 |
Scoring interpretation:
Immediate management based on severity:
| Severity | Actions |
|---|---|
| Mild (Grade 1) | Continue drug if benefit > risk; monitor; counsel patient |
| Moderate (Grade 2) | Consider dose reduction, temporary hold, or symptomatic treatment |
| Severe (Grade 3) | Discontinue suspected agent; provide supportive care; consider alternative therapy |
| Life-threatening (Grade 4) | Discontinue immediately; emergency supportive care; ICU level monitoring |
| Fatal (Grade 5) | Post-event analysis; report to FDA and institution |
Drug-specific reversal and management:
Internal documentation (in medical record):
External reporting: