Recommendations

Look-Alike Drug Names with Recommended Tall Man (Mixed Case) Letters

ISMP List of Look-Alike Drug Names with Recommended Tall Man (Mixed Case) Letters contains drug name pairs or larger groupings with recommended, bolded uppercase letters to help draw attention to the dissimilarities in look-alike drug names. The list includes mostly generic-generic drug names, although a few brand-brand or brand-generic names are included. The US Food and Drug Administration (FDA) list of drug names with recommended tall man (mixed case) letters was initiated in 2001 with the agency’s Name Differentiation Project.

Table 1 provides an alphabetized list of FDA-approved established drug names with recommended tall man (mixed case) letters.

Table 2 provides an alphabetized list of additional drug names with recommendations from ISMP regarding the use and placement of tall man (mixed case) letters. This is not an official list approved by FDA. It is intended for voluntary use by healthcare practitioners, drug information vendors, and medication technology vendors. Any product label changes by manufacturers require FDA approval.


How to cite: US Food and Drug Administration (FDA) and Institute for Safe Medication Practices (ISMP). FDA and ISMP Lists of Look-Alike Drug Names with Recommended Tall Man Letters. ISMP; 2023.

Table 1. FDA-Approved List of Generic Drug Names with Tall Man (Mixed Case) Letters

Drug Name With Tall Man Letters Confused With
acetaZOLAMIDE acetoHEXAMIDE*
acetoHEXAMIDE* acetaZOLAMIDE
buPROPion busPIRone
busPIRone buPROPion
CARBOplatin CISplatin
chlorproMAZINE chlorproPAMIDE
chlorproPAMIDE chlorproMAZINE
CISplatin CARBOplatin
clomiPHENE clomiPRAMINE
clomiPRAMINE clomiPHENE
cycloSERINE cycloSPORINE
cycloSPORINE cycloSERINE
DAUNOrubicin DOXOrubicin
dimenhyDRINATE diphenhydrAMINE
diphenhydrAMINE dimenhyDRINATE
DOBUTamine DOPamine
DOPamine DOBUTamine
DOXOrubicin DAUNOrubicin
glipiZIDE glyBURIDE
glyBURIDE glipiZIDE
hydrALAZINE  HYDROmorphone — hydrOXYzine
HYDROmorphone hydrALAZINE — hydrOXYzine
hydrOXYzine hydrALAZINE — HYDROmorphone
medroxyPROGESTERone methylPREDNISolone — methylTESTOSTERone
methylPREDNISolone medroxyPROGESTERone — methylTESTOSTERone
methylTESTOSTERone methylPREDNISolone — medroxyPROGESTERone 
migALAstat migLUstat
migLUstat migALAstat
mitoXANTRONE Not specified
niCARdipine NIFEdipine
NIFEdipine niCARdipine
prednisoLONE predniSONE
predniSONE prednisoLONE
risperiDONE rOPINIRole
rOPINIRole risperiDONE
sulfADIAZINE sulfiSOXAZOLE*
sulfiSOXAZOLE* sulfADIAZINE
TOLAZamide TOLBUTamide*
TOLBUTamide* TOLAZamide
traMADol traZODone
traZODone traMADol
vinBLAStine vinCRIStine
vinCRIStine vinBLAStine

* These drugs have been discontinued and are not marketed in the United States.

 

Table 2. ISMP List of Additional Drug Names with Tall Man (Mixed Case) Letters

Drug Name With Tall Man Letters Confused With
ALfentanil fentaNYL — SUFentanil
ALPRAZolam clonazePAM — LORazepam
aMILoride amLODIPine
amLODIPine aMILoride
ARIPiprazole RABEprazole
azaCITIDine azaTHIOprine
azaTHIOprine azaCITIDine
BUPivacaine ROPivacaine
carBAMazepine OXcarbazepine
CARBOplatin CISplatin
ceFAZolin cefoTEtan — cefOXitin — cefTAZidime — cefTRIAXone
cefoTEtan ceFAZolin — cefOXitin — cefTAZidime — cefTRIAXone
cefOXitin ceFAZolin — cefoTEtan — cefTAZidime — cefTRIAXone
cefTAZidime ceFAZolin — cefoTEtan — cefOXitin — cefTRIAXone
cefTRIAXone ceFAZolin — cefoTEtan — cefOXitin — cefTAZidime
CeleBREX CeleXA
CeleXA CeleBREX
chlordiazePOXIDE chlorproMAZINE
chlorproMAZINE chlordiazePOXIDE
CISplatin CARBOplatin
cloBAZam clonazePAM
clonazePAM ALPRAZolam — cloBAZam — cloNIDine — cloZAPine — LORazepam
cloNIDine clonazePAM — cloZAPine — KlonoPIN
cloZAPine clonazePAM — cloNIDine
cycloPHOSphamide cycloSERINE — cycloSPORINE
cycloSERINE cycloPHOSphamide — cycloSPORINE
cycloSPORINE cycloPHOSphamide — cycloSERINE
DACTINomycin DAPTOmycin
DAPTOmycin DACTINomycin
DEPO-Medrol SOLU-Medrol
dexAMETHasone dexmedeTOMIDine
dexmedeTOMIDine dexAMETHasone
diazePAM dilTIAZem
dilTIAZem diazePAM
DOCEtaxel PACLitaxel
DOXOrubicin IDArubicin
droNABinol droPERidol
droPERidol droNABinol
DULoxetine FLUoxetine — PARoxetine
ePHEDrine EPINEPHrine
EPINEPHrine ePHEDrine
epiRUBicin eriBULin
eriBULin epiRUBicin
fentaNYL ALfentanil — SUFentanil
flavoxATE fluvoxaMINE
FLUoxetine DULoxetine — PARoxetine
fluPHENAZine fluvoxaMINE
fluvoxaMINE flavoxATE — fluPHENAZine
guaiFENesin guanFACINE
guanFACINE guaiFENesin
HumaLOG HumuLIN
HumuLIN HumaLOG
hydrALAZINE hydroCHLOROthiazide —hydrOXYzine
hydroCHLOROthiazide hydrALAZINE† — hydrOXYzine 
HYDROcodone oxyCODONE
HYDROmorphone morphine — oxyMORphone
HYDROXYprogesterone medroxyPROGESTERone
hydrOXYzine hydrALAZINE — hydroCHLOROthiazide
IDArubicin DOXOrubicin — idaruCIZUmab
idaruCIZUmab IDArubicin
inFLIXimab riTUXimab
ISOtretinoin tretinoin
KlonoPIN cloNIDine
LaMICtal LamISIL
LamISIL LaMICtal
lamiVUDine lamoTRIgine
lamoTRIgine lamiVUDine
levETIRAcetam levOCARNitine — levoFLOXacin
levOCARNitine levETIRAcetam
levoFLOXacin levETIRAcetam
LEVOleucovorin leucovorin
LORazepam ALPRAZolam — clonazePAM
medroxyPROGESTERone HYDROXYprogesterone
metFORMIN metroNIDAZOLE
methazolAMIDE methIMAzole — metOLazone
methIMAzole methazolAMIDE — metOLazone
metOLazone methazolAMIDE — methIMAzole
metroNIDAZOLE metFORMIN
metyraPONE metyroSINE
metyroSINE metyraPONE
miFEPRIStone miSOPROStol
migALAstat migLUstat
migLUstat migALAstat
miSOPROStol miFEPRIStone
mitoMYcin mitoXANTRONE
mitoXANTRONE mitoMYcin
NexAVAR NexIUM
NexIUM NexAVAR
niCARdipine NIFEdipine† — niMODipine
NIFEdipine niCARdipine† — niMODipine
niMODipine niCARdipine† NIFEdipine
NovoLIN NovoLOG
NovoLOG NovoLIN
OLANZapine QUEtiapine
OXcarbazepine carBAMazepine
oxyBUTYnin oxyCODONE — OxyCONTIN‡ — oxyMORphone
oxyCODONE HYDROcodone — oxyBUTYnin — OxyCONTIN‡ — oxyMORphone
OxyCONTIN oxyBUTYnin — oxyCODONE — oxyMORphone
oxyMORphone HYDROmorphone — oxyBUTYnin — oxyCODONE — OxyCONTIN
PACLitaxel DOCEtaxel
PARoxetine DULoxetine — FLUoxetine
PAZOPanib PONATinib
PEMEtrexed PRALAtrexate
penicillAMINE penicillin
PENTobarbital PHENobarbital
PHENobarbital PENTobarbital
PHYSostigmine pyRIDostigmine
PONATinib PAZOPanib
PRALAtrexate PEMEtrexed
PriLOSEC PROzac
PROzac PriLOSEC
pyRIDostigmine PHYSostigmine
QUEtiapine OLANZapine
quiNIDine quiNINE
quiNINE quiNIDine
RABEprazole ARIPiprazole
raNITIdine* riMANTAdine
rifAMPin rifAXIMin
rifAXIMin rifAMPin
riMANTAdine raNITIdine*
RisperDAL rOPINIRole
risperiDONE rOPINIRole
riTUXimab inFLIXimab
romiDEPsin romiPLOStim
romiPLOStim romiDEPsin
rOPINIRole RisperDAL‡ — risperiDONE
ROPivacaine BUPivacaine
SandIMMUNE SandoSTATIN
SandoSTATIN SandIMMUNE
sAXagliptin SITagliptin
SITagliptin sAXagliptin — SUMAtriptan
Solu-CORTEF SOLU-Medrol
SOLU-Medrol DEPO-Medrol‡ — Solu-CORTEF
SORAfenib SUNItinib
SUFentanil ALfentanil — fentaNYL
sulfADIAZINE sulfaSALAzine
sulfaSALAzine sulfADIAZINE
SUMAtriptan SITagliptin — ZOLMitriptan
SUNItinib SORAfenib
tiaGABine tiZANidine
tiZANidine tiaGABine
traMADol traZODone
traZODone traMADol
valACYclovir valGANciclovir
valGANciclovir valACYclovir
ZOLMitriptan SUMAtriptan
ZyPREXA ZyrTEC
ZyrTEC ZyPREXA

    *    These drugs have been discontinued and are not marketed in the United States.
    †    These drug names are also on the FDA list. 
    ‡    Brand names always start with an uppercase letter. Some brand names incorporate tall man letters in initial characters and may not be readily recognized as brand names. A double dagger follows all brand names on the ISMP list. 

To promote standardization regarding which letters to present in uppercase/bold, ISMP follows a tested methodology whenever possible called the CD3 rule.19 The methodology suggests working from the left of the drug name first by capitalizing all the characters to the right once 2 or more dissimilar letters are encountered, and then, working from the right, returning 2 or more letters common to both words to lowercase letters. When the rule cannot be applied because there are no common letters on the right side of the name, the methodology suggests capitalizing the central part of the word only. When application of this rule fails to lead to the best tall man lettering option (e.g., makes names appear too similar, makes names hard to read based on pronunciation), an alternative option is considered. To promote consistency, ISMP suggests following the bolded, tall man lettering schemes provided by FDA and ISMP for the drug names listed in Tables 1 and 2 be followed to promote consistency.

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