Look-Alike Sound-Alike Drugs: A PTCB Safety Reference

What Are LASA Drugs?

Look-alike sound-alike (LASA) medications are drug pairs whose names look or sound similar, creating confusion during prescribing, dispensing, and administration. LASA errors are a leading cause of medication errors nationwide. The Institute for Safe Medication Practices (ISMP) and The Joint Commission both identify LASA drugs as a major patient safety concern.

High-Risk LASA Pairs

• hydrOXYzine vs hydrALAzine - Antihistamine vs antihypertensive
• metFORMIN vs methoTREXate - Diabetes drug vs chemotherapy/immunosuppressant
• predniSONE vs prednisoLONE - Different corticosteroid formulations
• cloNIDine vs cloNAZEPam - Antihypertensive vs benzodiazepine
• buPROPion vs busPIRone - Antidepressant vs anxiolytic
• cePHALexin vs ceFAZolin - Oral vs IV cephalosporin
• vinBLAStine vs vinCRIStine - Two different chemotherapy agents
• DOBUTamine vs DOPamine - Two different cardiac medications
• traMADol vs traZODone - Pain medication vs antidepressant
• SUMAtriptan vs ZOLMitriptan - Two different migraine medications

Tall Man Lettering

The FDA and ISMP recommend using tall man (uppercase) letters to highlight the differences between LASA drug names. For example, writing hydrOXYzine and hydrALAzine makes the distinguishing letters immediately visible. Many pharmacy management systems and automated dispensing cabinets use tall man lettering in their displays.

Prevention Strategies

• Store LASA drugs in separate locations, not adjacent bins
• Use shelf labels with tall man lettering and bright warning stickers
• Read the full drug name, not just the first few letters
• Verify the NDC number against the prescription at every fill
• Use barcode scanning as a verification step
• Include the indication on the prescription label when possible

LASA drug identification is a frequent PTCE exam topic. Memorize the most common pairs and the safety strategies that prevent errors.