AIMS, Focus on Error Prevention

Part I: Preventing Dispensing Errors of Similarly Named Drugs

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Ian Stewart, B.Sc.Phm., R.Ph.

The similarity of drug names continues to be a common factor in the dispensing of an incorrect drug product. Poor verbal or written skills can increase the risk of errors involving drugs with similar names.


A 50-year-old patient had been taking Cyclophosphamide 50mg once daily and Sulfatrim 400/80 three times weekly on a regular basis. On one occasion, the patient presented a written prescription to her usual community pharmacy for a refill of her Cyclophosphamide 50mg tablets.

While entering the prescription into the computer system, the pharmacy assistant entered “Cyclo” into the drug field and a list of options appeared which included both Cyclosporine 50mg and Cyclophosphamide 50mg. Due to similarity in drug names and equivalent strength, Cyclosporine 50mg was selected and entered in error.

The pharmacist who checked the prescription did not identify the computer entry error. The pharmacist also failed to notice that the patient had been taking Cyclophosphamide 50mg previously.

The pharmacist did notice that there was the potential for a drug interaction between Cyclosporine (the incorrect drug being dispensed) and Sulfatrim which was being taken by the patient. Cyclosporine 50mg was therefore dispensed with a note highlighting the potential drug interaction.

When the patient returned later to pick up what she thought was a refill of her Cyclophosphamide 50mg tablets, the pharmacist began to discuss the drug interaction and his concern. The patient explained that she had been taking the two drugs without any problem and was surprised that she was not advised of the drug interaction at the previous refill.

Noticing the discrepancy between the patient’s statement that she had been taking the drug and the fact that Cyclosporine was never dispensed to the patient previously, the pharmacist investigated and discovered the computer entry error.

Possible Contributing Factors:

  • Similarity between Cyclophosphamide 50mg and Cyclosporine 50mg.
  • The patient’s medication profile was not accessed to identify previous drug use and contraindications.
  • Cyclosporine 50mg once daily was not assessed for therapeutic appropriateness by considering the patient’s medical condition, other medication use, dosing interval, etc.


  • Educate all pharmacy staff about the potential for error when dispensing drugs with similar names.

An extensive list of problematic pairs can be accessed at: (Accessed January 18th, 2022).

  • When dispensing medications, always assess the appropriateness of the drug therapy.

Factors to be considered include the patient parameters, medication history, indication for use, the dose, dosing interval, duration of therapy, etc.

  • The patient’s medication history should always be consulted when processing both new and refill prescriptions to identify previous drug use and to assist in the identification of potential errors.
  • Develop a system to confirm and record the indication for use when dispensing any new drug therapy.
  • New drug therapy should always be flagged to ensure the patient receives appropriate counselling. In these instances, the patient should never be asked by support staff if they would like to speak to the pharmacist. Instead, the patient should be informed that the pharmacist needs to discuss aspects of the drug therapy. This is a key and often last opportunity to detect potential errors as this case demonstrates.
  • If there is any information that must be shared/discussed with the patient, write the information clearly on a coloured note pad or use a highlighter to ensure the note is not missed.

To see how to apply the AIMS Program using this article’s example, please read Part II: Putting AIMS Into Practice.

Please continue to send reports of medication errors in confidence to Ian Stewart at: Sharing your experience can prevent similar occurrences at other practice sites. Please ensure that all identifying information (e.g. patient name, pharmacy name, healthcare provider name, etc.) are removed before submitting.

<strong>Please be reminded that as part of the AIMS program, pharmacy professionals must:</strong>
  • Anonymously record all medication incidents and near misses via the AIMS medication event reporting platform.
  • Document appropriate details of medication incidents and near misses in a timely manner to support accuracy.
  • Analyze the incident in a timely manner for causal factors and commit to taking appropriate steps to minimize the likelihood of recurrence of the incident.
  • Promptly share learnings with all staff, including the appropriate details of a medication incident or near miss, including causal factors and actions taken as a result.

To see how to apply the AIMS Program using this article’s example, please read Part II: Putting AIMS Into Practice.

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