Medication Errors

Medication safety is a top priority for nurses and avoiding medication errors is critical. Find out what medication errors have recently been reported to the Institute for Safe Medication Practices (ISMP) and learn recommendations for best practices to help avoid these errors.

Methotrexate Mistakes

Methotrexate is an antimetabolite that interferes with DNA synthesis, repair, and cellular replication. Initially developed as a cancer treatment, methotrexate dosing is based on body surface area and is administered in cycles, rarely daily. The indications for methotrexate expanded to include treatment of rheumatoid arthritis and psoriasis which requires a low dose typically once or twice a week. Because only a few medications are dosed weekly, overdoses have been common, resulting in vomiting, mouth sores, stomatitis, skin lesions, liver failure, renal failure, myelosuppression, gastrointestinal bleeding, pulmonary symptoms, and death.
Methotrexate errors have occurred in the following scenarios:
  • Medication reconciliation and transitions-of-care: missteps happen when patients are admitted to the hospital and upon discharge to home or other healthcare facilities.
    • Orders may be entered incorrectly into the electronic medical record (EMR).
    • Errors occur with medication transcription.
    • Failure to verify the correct indication (cancer versus non-oncologic).
    • Medications are not reconciled prior to discharge.
  • Confusing instructions misunderstood by the patient: Methotrexate dosing is complex, often involving titration or escalating weekly doses. This can be very confusing for patients.
    • For example, an 8-week supply of 2.5 mg tablets (30 tablets) were dispensed with a prescription that read “Take 3 tablets by mouth 1 day for 2 weeks then increase to 4 tablets by mouth 1 day per week thereafter”. The patient erroneously took 3 tablets (7.5 mg) daily for 5 days which caused serious illness.
  • Look-alike and sound-alike drug names: Methotrexate has been mistaken for metolazone, a diuretic prescribed daily to treat congestive heart failure or kidney disease.
    • Both have similar dosage strengths: 2.5, 5, and 10 mg.
    • Both start with “met” and one pharmacist selected methotrexate instead of metolazone from the drop down menu in the computer system which did not flag the order for an oncology indication; the patient took 2.5 mg daily and died one month later.
  • Mix up with folic acid tablets: Methotrexate is a folic acid antagonist, thus folic acid may be prescribed to prevent folate deficiency and side effects such as mouth sores, abdominal pain, liver toxicity, hair loss, and anemia.
    • Folic acid tablets may resemble methotrexate tablets – both are small, yellow, and round.
The following strategies may help decrease the risk of methotrexate errors:
  • Include “take as directed” on all orders and prescriptions for oral methotrexate and emphasize clear instructions for weekly dosing.
  • Limit the patient’s prescription quantity to a 4-week (30-day) supply to decrease the risk of overdose.
  • Verify the dose and frequency of methotrexate on all medication lists and discharge instructions.
    • Update and edit the patient’s home medication list throughout the hospital stay so that it remains correct at discharge.
    • Review all discharge orders and prescriptions to ensure the dose and frequency are based on the right diagnosis.
  • Educate patients and provide them with verbal and written instructions that specify a weekly dosing schedule and stress the lethal risks with daily dosing.
    • Request all patients and family repeat back the instructions for taking oral methotrexate to confirm their understanding.
    • Advise patients to select one day of the week that they will take their oral methotrexate and to ask their pharmacist to include that on the label instructions (avoid Monday as that has been misread as “morning”).
    • Provide the patient with a visual calendar to emphasize the weekly dosing schedule.
    • If available, patients should ask the pharmacy to provide the oral methotrexate in a dose pack that helps remind them to take the right dose weekly.
  • Program pharmacy and prescriber order entry systems to default to a weekly dosing schedule.
  • Ensure that verification of an appropriate oncologic indication is required for daily orders in all order entry systems.
  • If folic acid is prescribed with methotrexate, instruct the patient on:
    • Differences between the drugs
    • Individual administration schedules
    • How to avoid mix-ups between the tablets (keep methotrexate tablets in the original packaging instead of weekly pill organizers)
  • Teach patients the symptoms of methotrexate toxicity and whom to contact to report symptoms.
  • Advise the patient to seek immediate medical attention if a dosing error occurs.

Drug Stem “-pril”

Drugs with the suffix “-pril” denote angiotensin-converting enzyme (ACE) inhibitors which work by blocking angiotensin II production, a hormone that induces vasoconstriction. ACE inhibitors cause vasodilation resulting in reduced blood pressure, increased cardiac perfusion, and decreased cardiac workload. Indications include:
  • Hypertension
  • Heart failure with reduced ejection fraction
  • Preserve renal function in diabetes
  • Improve heart function following a myocardial infarction
  • Reduce the risk of myocardial infarction, stroke, and death from cardiovascular disease
A major risk of ACE inhibitors is fetal toxicity and therefore should be discontinued with pregnancy. Side effects include: dry cough, dizziness, hyperkalemia, headache, fatigue, acute renal failure and angioedema. Assess blood pressure and renal function prior to starting therapy, two weeks after starting an ACE inhibitor and at regular intervals. If hyperkalemia cannot be corrected or serum creatinine increases greater than 30% above baseline within the first 6 to 8 weeks of therapy, stop the ACE inhibitor.
ACE inhibitors should be used with caution with the following medications:
  • Non-steroidal anti-inflammatory drugs (NSAIDS) may decrease the antihypertensive effects of ACE inhibitors.
  • Monitor lithium levels closely as ACE inhibitors will increase its blood concentration.
  • Avoid concurrent use with neprilysin inhibitors to avoid increased risk of angioedema.
  • Avoid concurrent use with aliskiren as this will increase the nephrotoxic effect of ACE inhibitors.
  • Quinipril will reduce the absorption of tetracyclines so these drugs should be taken a minimum of 2 hours apart.
There are currently eleven ACE inhibitors available in the U.S. and ten combination products:
  • Benazepril (Lotensin): benazepril and amlodipine (Lotrel); benazepril and hydrochlorothiazide (Lotensin HCT)
  • Captopril: captopril and hydrochlorothiazide
  • Enalapril (Epaned, Vasotec): enalapril and hydrochlorothiazide (Vaseretic)
  • Enalaprilat: no combination products
  • Fosinopril: fosinopril and hydrochlorothiazide
  • Lisinopril (Prinivil, Qbrelis, Zestril): lisinopril and hydrochlorothiazide (Zestoretic)
  • Moexipril: moexipril and hydrochlorothiazide
  • Perindopril: perindopril and amlodipine (Prestalia)
  • Quinapril (Accupril): quinapril and hydrochlorothiazide (Accuretic)
  • Ramipril (Altace): no combination products
  • Trandolapril: trandolapril and verapamil (Tarka)

Safety Issues

Insulin Pump Hacking
Certain insulin pumps have been recalled due to suspected cybersecurity risks. The Food and Drug Administration (FDA) found that unauthorized individuals could connect wirelessly to nearby MiniMed insulin pumps (made by Medtronic) and change the pump settings, causing harm to the patient. Patients waiting for a replacement should seek medical help immediately if they suspect their insulin settings have changes or if they have symptoms of severe hypoglycemia or diabetic ketoacidosis. The FDA is asking device manufacturers to assess their pump cybersecurity and alert the FDA to any potential issues.

Oral Syringe Markings
Some prepackaged oral syringes (i.e. acetaminophen made by Precision Dose) are still being manufactured with both mL and teaspoon markings. As a best practice, hospitals should purchase and use oral syringes that only display the metric scale (mL) to avoid confusion.

Drug Abbreviations
Drug name abbreviations should not be used. One provider used the abbreviation “ILK” for intralesional Kenalog which was misinterpreted as interleukin. The error was caught however, unapproved abbreviations will cause great confusion and should be avoided. Hospitals should display a list of error-prone abbreviations that should never be used and provide their staff with an accessible online database of medical abbreviations. If drug abbreviations are used in the clinical setting, the prescriber should be contacted for clarification.

Institute for Safe Medication Practices. (2019). Nurse Advise-ERR. Retrieved from Institute for Safe Medication Practices: 

Previous issues



July: Reducing Risks in Medication Administration November: Dangerous IV Push Medication Practices
June: Independent Double Checks October 2018: Tracheostomy Balloon Port
May: Newborn Patient Mixups September 2018: Errors in Clinical Education
April: Hefty Subcutaneous Doses August 2018: Smart Pump Low Concentration
March: Epidural Antibiotic Mix Up July 2018: Ellipta
February: Criminal Indictment June 2018: Rituxan Subcutaneous vs IV
January: Confusing Glucometer Results May 2018: Nebulized Medications
  April 2018: Surgical Fires
  March 2018: Treating Hyperkalemia With Insulin
  February 2018: Barcode Errors
  January 2018: Smartpump Miscommunication



  December 2017: Ongoing Debate Texting Medical Orders
  November 2017: Dangerous Injection Practices
  October 2017: Medication Safety Assessment
  September 2017: Heparin Induced Thrombocytopenia
  August 2017: Insulin Syringe Issues
  July 2017: Texting and Patient Management
  June 2017: Verbal Order Errors
  May 2017: Unsafe Infusions & Injection Practices
  April 2017: Generic Medication Names
  March 2017: Medication Errors at Home
  February 2017: Errors in Irrigation
  January 2017: Use Technology Wisely

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