Rx Update: August 2001

Look-Alike, Sound-Alike Drug Name Confusion

Mary Ross, R.Ph., M.B.A., Barbara Mutnick, R.Ph., M.H.P., and Joan Murhammer, R.Ph.
Peer Review Status: Internally Reviewed

Many drug names have been confused based on illegible handwriting, poor pronunciation, and other miscommunication factors. As new products are approved additional confusions can occur. The United States Pharmacopeia (USP) Web site, http://www.usp.org/ contains a complete list of these problem names. This article highlights a few of the drug name confusions that have been reported to the USP.

Numerous errors have occurred in the pediatric population when ranitidine (Zantac®) syrup and cetirizine (Zyrtec®) syrup have been mistakenly interchanged. Ranitidine is an H2 receptor blocker and cetirizine is an antihistamine. Although these medications do not have overlapping dosage strengths, both are available in the syrup dosage form.

Bisoprolol (Zebeta®), a beta-adrenergic blocking agent, and glyburide (Diabeta®), an oral sulfonylurea, have very similar sounding trade names and are both available in 5 mg tablets.

Tamsulosin (Flomax®), an alpha-1-adrenergic blocker, and albuterol (Volmax®), a sympathomimetic bronchodilator, also have very similar sounding trade names. Tamsulosin is available in a 0.4 mg tablet and albuterol is available in a 4 mg strength.

Confusion has been reported between the antidepressant nefazodone (Serzone®) and the antipsychotic quetiapine (Seroquel®). Both drugs are available as 100 mg and 200 mg tablets.

Another hospital recently reported a situation which resulted in tirofiban (Aggrastat®), a glycoprotein IIb/IIIa inhibitor, being ordered instead of argatroban, an anticoagulant used for prophylaxis or treatment of thrombosis.

Balsalazide (Colazal®), a drug used to treat mild to moderate ulcerative colitis, could easily be confused with the antipsychotic clozapine (Clozaril®).

Docetaxel (Taxotere®) and paclitaxel (Taxol®) are both antimitotic cancer chemotherapeutic agents; however, they have different indications and recommended doses.

Fluoxetine (Sarafem®), an antidepressant can be misheard as clomiphene (Serophene®), an ovulatory stimulant, when a prescription is ordered by phone.

There is a developing nomenclature issue with insulin glargine (Lantus®), a new insulin product approved for use in both type 1 and type 2 diabetes mellitus. There is concern that a written order may be misinterpreted as "lente" insulin.

The likelihood of confusing similar sounding drugs is decreased when prescribers clearly print both the brand and generic names. Synonyms and abbreviations should always be avoided. Adding the indication for use may also help to clarify the order. All health providers should ensure that the agents prescribed for patients conform to therapy consistent with the patient's diagnosis. Incorrect routes of administration or doses that seem relatively large or small as compared to commercially available strengths should also warrant investigation.

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