Safe prescribing, calculations and medicines information

Prescription components, numeracy, formulations/routes, BNF/formularies, evidence and decision support.

Pre-prescribing foundation: this module develops knowledge and judgement for formal prescribing education; it does not authorise prescribing.

• Identify the components of a safe, complete prescription.
• Use units and dimensional sense-checking to reduce calculation error.
• Navigate BNF, formulary and guideline information in context.
• Recognise risks from formulations, routes, decimal points and electronic defaults.
• Know when independent checking or specialist advice is required.

Safe prescription writing depends on correct patient, medicine, formulation, route, dose, frequency, duration and legal/administrative requirements.

Numeracy teaching should emphasise units, dimensional sense-checking and independent verification when calculations are unfamiliar or high risk.

BNF/formulary information must be read in context: indication, contraindication, cautions, interactions, renal/hepatic advice, monitoring and local restrictions.

Electronic defaults and alerts reduce some errors but can create automation bias and alert fatigue.

1. Define the clinical problem and whether prescribing is indicated.
2. Gather the patient-specific assessment and diagnostic information needed.
3. Check competence, professional authority and employer/service scope.
4. Compare reasonable options using current authoritative sources.
5. Agree the plan with the patient, including uncertainty and alternatives.
6. Prescribe accurately only when the decision is justified.
7. Document, monitor, review and safety-net.

Module emphasis: Verify patient, medicine, formulation, route, dose, units, frequency and duration; independently check unfamiliar or high-risk calculations and sense-check the result.

Scenario 1. A decimal-point error produces a tenfold dose.

Reasoning prompt: Verify patient, medicine, formulation, route, dose, units, frequency and duration; independently check unfamiliar or high-risk calculations and sense-check the result.

Scenario 2. An e-prescribing default selects the wrong formulation.

Reasoning prompt: Verify patient, medicine, formulation, route, dose, units, frequency and duration; independently check unfamiliar or high-risk calculations and sense-check the result.

Scenario 3. The BNF dose range is broad but the patient’s indication and renal function narrow the safe choice.

Reasoning prompt: Verify patient, medicine, formulation, route, dose, units, frequency and duration; independently check unfamiliar or high-risk calculations and sense-check the result.

• The electronic system will prevent unsafe doses.
• If a medicine is in the BNF, I am competent to prescribe it.
• A calculator result does not need a clinical sense-check.

• What clinical problem am I trying to solve, and is prescribing indicated?
• What information is missing before a safe decision can be made?
• Is this within my current competence, professional authority and employer/service scope?
• Which current authoritative medicine or guideline source should I check?
• What patient-specific factors change benefit, harm, dose, route or monitoring?
• What will I document, monitor, review and safety-net?
• When should I seek supervision, pharmacy advice, specialist input or urgent escalation?

Optional reflection: Without entering identifiable patient or employer information, identify one capability you would need to strengthen before prescribing independently in this area.

• Safe prescription writing depends on correct patient, medicine, formulation, route, dose, frequency, duration and legal/administrative requirements.
• Numeracy teaching should emphasise units, dimensional sense-checking and independent verification when calculations are unfamiliar or high risk.
• BNF/formulary information must be read in context: indication, contraindication, cautions, interactions, renal/hepatic advice, monitoring and local restrictions.
• Electronic defaults and alerts reduce some errors but can create automation bias and alert fatigue.

Check current versions for time-sensitive decisions.

• BNF-01 - BNF / NICE: British National FormularyOpen official source
• LAW-01 - UK Parliament: Human Medicines Regulations 2012Open official source
• RPS-01 - Royal Pharmaceutical Society: A Competency Framework for All Prescribers (2021)Open official source