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Avoid errors in drug names: use the international nonproprietary name

Using a drug’s international nonproprietary name (INN) is particularly helpful in avoiding confusion between similar brand names.

The brand names dreamed up by pharmaceutical companies give little or no information about a drug’s composition. Some similar-sounding brand names conceal different drugs, which can lead to confusion and expose patients to avoidable adverse effects.

Three cases illustrate such confusion. A 52-year-old patient was admitted to hospital for bleeding after an illegible hand-written prescription led a pharmacist to confuse the anticoagulant Previscan° (fluindione) with Permixon° (Serenoa repens) prescribed for a urinary disorder. A 68-year-old patient was admitted to hospital for a haemorrhagic syndrome resulting from the same type of mix-up. An 86-year-old woman was hospitalised for a haemorrhagic syndrome caused by Previscan° (fluindione) being confused with Preservision°, a food supplement to improve vision.

The various typographic devices used to differentiate brand names are not sufficient to avoid drug errors with sometimes severe clinical consequences. There are fewer international nonproprietary names (INN) than there are brand names, which is an advantage. INN names also break down into one or several main stems which provide information on the nature and the effects of the substances. INNs are less frequently cited in reports of name confusion. The INN is a shared language for describing, prescribing, dispensing and using medicines, with the communication then tailored to each patient.

©Prescrire October 2009

"Use the INN to avoid confusion between drugs" Prescrire Int 2009; 18 (103): 214 (pdf, subscribers only).

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