Safe prescribing, administration and monitoring — formative SAQs

SAQ 1 (10 marks)

A 6-year-old, 20 kg, on the ward for a skin infection is prescribed flucloxacillin and gentamicin. The team uses extended-interval gentamicin dosing. [9]

1. Outline the medication-use process and state which stage generates the most errors in children, with the evidence. (3) [1]
2. Describe the rights of medication administration and explain what makes a double-check effective for a high-alert medicine. (3) [6]
3. State how you would monitor the gentamicin, including the sample timing and the target. (4) [9]

Model answer

The medication-use process runs through prescribing, transcribing, dispensing, administering, and monitoring. Prescribing generates the most errors in children — Kaushal's cohort found medication errors in roughly 6 in 100 paediatric inpatient orders, highest in PICU and NICU, with the prescribing stage the largest contributor — because every paediatric dose is weight-based and therefore an arithmetic act. [1] [2]

The rights of administration are right patient (two identifiers), right drug, right dose (independently re-calculated by weight), right route, right time and frequency, and right reason and documentation, with the modern additions of right formulation, right rate for infusions, and right response by monitoring the effect. A double-check is effective only when it is independent: the second person re-calculates the dose and pump settings from the weight and the reference, then compares — not merely agreeing with the first number. Reserve independent checks for high-alert medicines such as insulin, opioids, concentrated electrolytes, anticoagulants, and chemotherapy, where they have the highest yield. [6]

For extended-interval gentamicin, take a trough level immediately before the second or third dose; the target is a trough less than 1 mg per litre, which avoids accumulation and the nephro- and ototoxicity that follow it. Review renal function before and during therapy, extend the interval or hold the dose if the trough is above target, and tie each level to a documented action so a result is never merely filed. [9]

SAQ 2 (10 marks)

A nurse reports that a child received twice the intended dose of an opioid infusion overnight because the pump was set to the wrong rate. The child is drowsy but arousable, with a respiratory rate of 10. [6]

1. Describe your immediate management. (4) [6]
2. Outline the layered system-level changes that would prevent recurrence, and justify why a single intervention is insufficient. (4) [8]
3. Explain the role of vancomycin therapeutic monitoring and its current target, to illustrate how monitoring closes the safety loop. (2) [11]

Model answer

Stop the opioid infusion immediately and assess and support the airway, breathing, and circulation; the child with a respiratory rate of 10 needs ventilation support and the opioid antagonist naloxone, titrated to restore adequate respiration rather than full alertness. Escalate to a higher level of care for ongoing observation, because the half-life of the opioid may exceed that of naloxone and re-sedation can recur. [6]

Prevention is a layered system rather than any single fix, modelled by the Swiss-cheese principle: prescribe from a standard reference with the weight-based calculation shown; use computerised order entry with decision support and standard concentrations; embed unit-based pharmacists who intercept prescribing errors; standardise infusion concentrations and use ready-to-administer products to remove compounding error; apply the rights with an independent double-check for the opioid; and audit and report the event so a weakness becomes a system change. The Cochrane review found bundled, system-level interventions reduce error rates, while reducing actual patient harm remains harder to prove — which is precisely why one intervention alone is insufficient. [8] [2]

Monitoring closes the loop for narrow-therapeutic-index drugs. For vancomycin in serious methicillin-resistant staphylococcal infection, the 2020 consensus guideline shifts monitoring from trough toward the area under the curve over 24 hours relative to the minimum inhibitory concentration, targeting an AUC to MIC ratio of 400 to 600, with the upper bound set to limit nephrotoxicity; where trough-only monitoring remains, a trough of 10 to 15 mg per litre (15 to 20 mg per litre for severe infection) approximates the target. [11]