Prescribing Skills (Part 5 of 8 - Drug Calculation Skills)

Drug Calculation Skills

Principles

Mutliple Choice Question

You have just started your shift. A nurse asks you to review a prescription which she felt was incorrect. Your colleague on the previous shift had prescribed 7500mg twice a day.  She has never given Amikacin before. She felt something was wrong as it would take 15 vials to make up each dose.


This is a 50kg female who requires Amikacin for a serious Gram-negative infection. Using your BNF, calculate the correct dose for this patient for a twice daily regimen.

Always recheck a prescription if you feel the volume of the drug is larger than usual.

(ie. too many tablets, vials etc )

The maximum you should really give a patient:-


TABLETS: No more that 4 in any one dose (unless prednisolone, methotrexate etc.)


LIQUIDS: 5-20 mL for any one dose


INJECTIONS: 1-10mL for any one dose


INFUSIONS: 2-3 L per day

Teacher's Comment
  • Always refer to the BNF when unsure, or prescribing an uncommon drug
  • If you are not sure about how to prescribe a medication, ask. Senior doctors, ward sisters, nurses, pharmacists and microbiologists are common sources of help.