Description

Searches for strings in the data set that most closely match the term pararmeter.

This function is useful for strings where an exact or normalized string match (findRxcuiByString) does not find the desired results. For example, consider the following queries:

Results can optionally be limited to Active concepts with the option parameter.

Results include the score, rank, RxCUI and RxAUI of the closest strings. The strings themselves (RXNCONSO STR field) are not returned due to the proprietary nature of some of the strings. They can be retrieved by calling the RxNorm API function getProprietaryInformation using the RxCUI and RxAUI.

Results are returned in order by the quality of the lexical match, best results first (rank=1). The maxEntries parameter gives some control over the number of results, but more or fewer may be returned to avoid splitting a rank.

For more information about the approximate-matching algorithm, see Approximate Matching in the RxNorm API.

Scope

Selectable (see parameters):

• Active: concepts in the current RxNorm data set that have an atom with SAB=RXNORM and SUPPRESS=N

• Current: concepts in the current RxNorm data set that have an atom with SUPPRESS=N

Parameters

All query parameters are case-insensitive.

Output structure

Results are available as either XML or JSON.

• The XML result has the root element rxnormdata. It is described in the XML Schema for the RxNorm API; the relevant element structure is summarized below. Elements that would be empty might be left out.

• The JSON result is an object {...}, analogous to the content of the XML rxnormdata. Fields that might occur multiple times in the XML are expressed as an array. Fields that would be empty might be null or left out. Numbers are expressed as strings.

Both XML and JSON results follow the same outline:

rxnormdata

Root element in XML, or anonymous object in JSON

approximateGroup

inputTerm

Term sought

maxEntries

Requested number of results

option

Requested option

comment

Message from the search engine

candidate (array)

rxcui

RxNorm identifier

rxaui

RxNorm RXAUI (string identifier) that matches

score

Match score (higher is better)

rank

1 for all best matches, 2 for all second-best matches, etc.

See also

• findRxcuiByString

Example: Terms like "zocor 10 mg"

XML: https://rxnav.nlm.nih.gov/REST/approximateTerm?term=zocor%2010%20mg&maxEntries=4

JSON: https://rxnav.nlm.nih.gov/REST/approximateTerm.json?term=zocor%2010%20mg&maxEntries=4

An XML result is shown below.

<rxnormdata>
    <approximateGroup>
        <inputTerm>zocor 10 mg</inputTerm>
        <maxEntries>4</maxEntries>
        <comment/>
        <candidate>
            <rxcui>104490</rxcui>
            <rxaui>2651386</rxaui>
            <score>75</score>
            <rank>1</rank>
        </candidate>
        <candidate>
            <rxcui>563653</rxcui>
            <rxaui>12297106</rxaui>
            <score>75</score>
            <rank>1</rank>
        </candidate>
    </approximateGroup>
</rxnormdata>