USP Quality Review

No. 73, Issued March 2000

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Amrinone Becomes Inamrinone

The U.S. Pharmacopeia (USP) Nomenclature Committee and the United States Adopted Names (USAN) Council have approved changing the nonproprietary name and the current official monograph title of amrinone to inamrinone (eye-nam-ri-none). The name change from amrinone to inamrinone is scheduled to become effective on July 1, 2000, with the Second Supplement of the United States Pharmacopeia-National Formulary (USP–NF).

Reported Mix-ups
In September 1999, the USP and the USAN Council jointly recommended nomenclature changes for the drug substances amrinone and amiodarone (Pharmacopeial Forum Vol. 25, No. 5, Sept.-Oct. 1999; USP Quality Review No. 69). The similarity of the names was reported to cause confusion between the products, resulting in medication errors. At present, fourteen medication errors involving the drugs have been reported to the USP Medication Errors Reporting (MER) Program. The consequences of the medication errors have included reports of patient injury and death.

Both drugs are frequently used in emergency/code situations where the urgency to treat critically ill patients immediately creates circumstances in which orally communicated orders are frequently essential. Each drug, however, is used for treatment of a different cardiac problem. Three reports of mix-ups involving amrinone and amiodarone were recently received by the MER Program. The cases are illustrative of errors that may result from the verbal similarity of the names. In one current report, an order for amiodarone was telephoned into the pharmacy during a code situation. The dose was not specified. The pharmacist mistakenly dispensed amrinone, subsequently realized the error, and was able to retrieve the product from the emergency department before the drug was administered. The two other reports cite incidents where amrinone verbal orders were mistaken for amiodarone. In one situation, a nurse incorrectly transcribed a physician's telephone order. Because the dose was unusual, the pharmacist recognized the error and verified the correct drug with the physician. In the second case, a physician incorrectly interpreted a poison control center's recommendation. In this occurrence, because a dose and infusion rate were not specified, a clinical pharmacist intervened to assist the physician, and the error was detected. Fortunately, in each of these cases, a pharmacist's intervention prevented the patient from receiving the wrong medication.

Practitioners Provide Valuable Input
A practitioner survey to solicit comment from health care professionals regarding the effectiveness of the USP/USAN proposed nomenclature changes was prepared and widely disseminated. Representatives from multiple health care disciplines responded, including pharmacists, nurses, and physicians. Data from the returned surveys were tabulated and summarized for review by the USP Nomenclature Committee and the USAN Council. More than 400 responses were included in the presented data. The USP Practitioner and Product Experience division continues to receive responses.

The results of the practitioner survey supported the proposal, with 379 (�86%) responses in the affirmative and 57 (�13%) in opposition. Originally, in addition to changing the name amrinone to inamrinone, the USP and the USAN Council had proposed changing the name amiodarone to camiodarone. It was observed that a number of respondents, although voting in opposition to the proposal, advocated changing only one of the names rather than both. This argument was found persuasive. The USP and the USAN Council voted to postpone any name change for amiodarone, in order to observe the impact of changing amrinone to inamrinone.

USP & USAN Decisions

The following decisions were agreed on:

approve changing only the current official monograph titles, as proposed in PF 25(5), to be effective with the Second Supplement, July 1, 2000; i.e., change AMRINONE to INAMRINONE change AMRINONE INJECTION to INAMRINONE INJECTION
postpone the recommendation for changing the name AMIODARONE HYDROCHLORIDE and consider appropriate action after observing how the amrinone nomenclature changes have progressed.
continue with an educational campaign to alert practitioners on the importance of differentiating the names of the two drugs.

USP thanks all of the survey respondents. Indeed, the data collected from the questionnaires were influential and had a significant impact on the final decision made for the proposed actions.

Continued Vigilance Is Necessary
The USAN Council functions principally to serve the health professions of the United States. In this age when medication information and literature is readily accessible via the World Wide Web and drug manufacturers produce and market products in multiple countries, the need is evident for cooperation regarding nomenclature on an international level. The World Health Organization (WHO) collaborates closely with national nomenclature committees, such as the USAN Council, to recommend a single name of worldwide acceptability for each active substance to be marketed as a pharmaceutical. This name is known as the substance's International Nonproprietary Name (INN), and many member states recognize it as the sole or preferred nonproprietary name for use within their respective territories. At present, approximately 7,000 INN's have been published. The USAN Council established the name amrinone in 1967, and subsequently, the WHO established the name as the substance's INN.

Unfortunately, no procedure or mechanism currently exists for changing a recommended INN. The name amrinone will remain in use in other countries throughout the world. After the name change to inamrinone becomes official, there may be instances when product might be purchased for use in the United States from a foreign manufacturer. In these situations, the labeling may exhibit the INN nomenclature amrinone. Practitioners need to be vigilant to this scenario and proactively implement appropriate procedures to address possible confusion.

Similarly, at the time the name inamrinone becomes official, it is expected that products labeled with the amrinone nomenclature will still be in inventories. Practitioners are called upon to take appropriate precautions and to develop strategies that will ensure smooth transition to products with the new nomenclature.

It is anticipated that adoption of distinctive nomenclature in the interest of diminishing or preventing further patient misadventures will be welcomed by health practitioners and pharmaceutical manufacturers alike. USP is disseminating news releases and announcements to inform the health care community of the impending changes to the titles of the USP monographs. Likewise, in the interest of alerting health professionals regarding product selection and recognition, USP is urging manufacturers and marketers of these articles to publicize the change.