Prescription analysis

Clinical Pharmacology and Toxicology

A 54 year old lady is a new patient at her GP surgery having moved house. She has taken methotrexate for several years and told the GP she takes 6 (six) 2.5mg tablets daily.

Patient ID
Mr A Pain
1/1/431
Pain Street
Painland
Hospital no:334867
Special InstructionsAllergies
Nystatin
Name
Methotrexate

Route
oral

Frequency
OD
Dose
15 mg

Comments
Nil
Time given
0800

Which of the following statements is correct?

(You can and should use the BNF to assist you answering this question).

  • Incorrect frequency of medication
  • Incorrect route
  • Incorrect dose of methotrexate (i.e. not 15mg)
  • Correct prescription
  • Contraindicated drug

  1. Incorrect frequency of medication
  2. Incorrect route
  3. Contraindicated drug

OD = once daily
BD = twice daily
TDS = three times a day
QDS = four times a day

But… Methotrexate is given once weekly. This prescribing error has lead the MHRA (Medicines and Healthcare Regulation Agency) to issue strict guidelines on this.

Although it has a short half life (approx 12 hours) if given daily it will rapidly accumulate producing toxicity including:

Marrow suppression and bone marrow failure
Bruising
Hepatitis
Acute renal failure