Interactions, Contraindications and Patient-Specific Adjustment
Identify medicines made unsafe or ineffective by another medicine, a contraindication or the patient's changing physiology.
How to prepare for the PSA
Combine patient-centred prescribing judgement with fast BNF navigation, reliable calculations, complete prescriptions and explicit monitoring and communication.
Core concepts
Concept 1
Review tasks may turn on a clinically important interaction, a contraindication or a dose or route that no longer suits the patient.
Exam cue: Look for a new patient fact that changes the status of an existing medicine.
Concept 2
Kidney or liver dysfunction, pregnancy, frailty, electrolyte disturbance and acute illness can change the safety of an existing prescription.
Exam cue: When checking an interaction, identify the clinically important consequence and which listed prescription the lead-in asks you to select.
Concept 3
The task is to identify the relevant prescription or prescriptions, not merely name the underlying pharmacology.
Exam cue: Use the BNF when the precise interaction, caution or adjustment is beyond core recall.
Risk pitfalls and guardrails
Flagging every theoretical interaction regardless of clinical importance.
Guardrail: Do not let a familiar medicine, reference search or calculator output replace patient-specific safety checks and escalation.
Confusing a reason to monitor with an absolute reason to stop treatment.
Guardrail: Do not let a familiar medicine, reference search or calculator output replace patient-specific safety checks and escalation.
Selecting the medicine named in the lead-in when the task asks for the interacting prescription.
Guardrail: Do not let a familiar medicine, reference search or calculator output replace patient-specific safety checks and escalation.
Memory anchors
Interaction Consequence
Judge an interaction by its clinically important effect in the stated patient.
Contraindication
A contraindication makes a treatment inappropriate in the defined circumstance.
Caution
A caution may require adjustment, monitoring or advice rather than automatic discontinuation.
Organ Function
A change in kidney or liver function can alter exposure and dose suitability.
Lead-In Target
Select the prescription requested by the task, not simply the most familiar medicine.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
A patient taking sildenafil develops chest pain and requests glyceryl trinitrate. What is safest?
A patient on warfarin starts metronidazole. What adjustment process is needed?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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