Stockley's vs BNF (2025): The Mechanism vs The Rule

Last reviewed: 2025-12-19 · Reviewed by

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At a Glance

Who is it for?

Stockley's Drug Interactions:Pharmacists / Specialists

BNF (British National Formulary):All Prescribers

Why choose Stockley's Drug Interactions?

  • **Mechanism Explained**: Details CYP450 induction/inhibition.
  • **Evidence Based**: Cites the specific case reports/trials behind the warning.
  • **Management Advice**: Advises on how to mitigate risk (e.g. 'Monitor INR', 'Space doses').

Why choose BNF (British National Formulary)?

  • **Speed**: Simple Red/Orange/Green flag system.
  • **Authority**: The legal baseline for NHS prescribing.
  • **Accessibility**: Integrated into every GP system and free online.
  • **Breadth**: Covers every licensed drug pair.

Feature Comparison

CapabilityStockley's Drug InteractionsBNF (British National Formulary)
Detail LevelDeep / MolecularHigh-level / Binary
Primary UserPharmacistGeneralist Doctor
FocusSolving the problemFlagging the problem

In-Depth Analysis

Overview

The BNF is a safety net. Its interaction checker is designed to stop you making a mistake. It is often binary: "Severe Interaction – Avoid." For a junior doctor or GP, this is usually enough instruction to stop.

Stockley's is a problem solver. It is the tool used by pharmacists when a combination is clinically necessary despite the flag. It explains why the interaction happens (e.g., "Drug A increases levels of Drug B by 20%"). This allows the clinician to make a nuanced decision, perhaps reducing the dose rather than stopping the drug.

Key Differences

BNF is for spotting the problem. Stockley's is for solving it.

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Use-Cases

Routine Prescribing Check

When to choose Stockley's Drug Interactions

  • Too slow and detailed.

When to choose BNF (British National Formulary)

  • **Winner.** Essential safety check before signing a script.

Essential Polypharmacy

When to choose Stockley's Drug Interactions

  • **Winner.** Helps you safely combine drugs that the BNF simply flags as 'Avoid' by explaining the real risk.

When to choose BNF (British National Formulary)

  • Often too risk-averse; stops you prescribing necessary combinations.

Understanding 'Why'

When to choose Stockley's Drug Interactions

  • **Winner.** explains the pharmacokinetics.

When to choose BNF (British National Formulary)

  • Simply states 'interaction exists'.