lookup_rxnorm

Instructions

Implementation Reference

• index.js:258-265 (registration)

  Tool registration for 'lookup_rxnorm' using server.tool() with a description and Zod schema for drug_name input.

  server.tool(
    "lookup_rxnorm",
    "Look up a drug's RxNorm concept, RxCUI identifier, ingredient relationships, and drug class. RxNorm is the standard for drug interoperability across EHR systems.",
    {
      drug_name: z
        .string()
        .describe("Drug name (brand or generic, e.g. 'abilify', 'aripiprazole', 'ozempic')"),
    },

• index.js:261-265 (schema)

  Input schema defining drug_name as a Zod string describing the drug name (brand or generic).

  {
    drug_name: z
      .string()
      .describe("Drug name (brand or generic, e.g. 'abilify', 'aripiprazole', 'ozempic')"),
  },

• index.js:266-355 (handler)

  Handler function that calls RxNav APIs to look up RxCUI, find approximate matches if needed, fetches properties, ATC class, and related ingredients/brands, then returns formatted markdown text.

  async ({ drug_name }) => {
    // Get RxCUI
    const searchData = await apiFetch(
      `${RXNAV_BASE}/rxcui.json?name=${encodeURIComponent(drug_name)}&search=2`
    );
  
    const rxcui = searchData?.idGroup?.rxnormId?.[0];
  
    if (!rxcui) {
      // Try approximate match
      const approxData = await apiFetch(
        `${RXNAV_BASE}/approximateTerm.json?term=${encodeURIComponent(drug_name)}&maxEntries=5`
      );
      const candidates = approxData?.approximateGroup?.candidate || [];
      if (!candidates.length) {
        return {
          content: [{
            type: "text",
            text: `No RxNorm concept found for "${drug_name}". Check spelling or try generic name.`
          }]
        };
      }
  
      const lines = candidates.slice(0, 5).map(
        c => `- **RxCUI ${c.rxcui}** — Score: ${c.score} (${c.name || "name not available"})`
      );
      return {
        content: [{
          type: "text",
          text: [
            `## RxNorm: Approximate Matches for "${drug_name}"`,
            "",
            ...lines,
            "",
            "Re-run with the exact name for full details."
          ].join("\n")
        }]
      };
    }
  
    // Get properties
    const [propsData, classData, relData] = await Promise.all([
      apiFetch(`${RXNAV_BASE}/rxcui/${rxcui}/properties.json`).catch(() => null),
      apiFetch(`${RXNAV_BASE}/rxclass/class/byRxcui.json?rxcui=${rxcui}&relaSource=ATC`).catch(() => null),
      apiFetch(`${RXNAV_BASE}/rxcui/${rxcui}/related.json?tty=IN+BN+SCD`).catch(() => null),
    ]);
  
    const props = propsData?.properties || {};
    const classes = classData?.rxclassDrugInfoList?.rxclassDrugInfo || [];
    const related = relData?.relatedGroup?.conceptGroup || [];
  
    const ingredients = related
      .find(g => g.tty === "IN")
      ?.conceptProperties?.map(c => c.name) || [];
    const brandNames = related
      .find(g => g.tty === "BN")
      ?.conceptProperties?.map(c => c.name) || [];
    const atcClasses = classes.slice(0, 3).map(
      c => `${c.rxclassMinConceptItem?.className} (${c.rxclassMinConceptItem?.classId})`
    );
  
    const text = [
      `## RxNorm: ${props.name || drug_name}`,
      "",
      `### Identifiers`,
      `- **RxCUI:** ${rxcui}`,
      `- **Name:** ${props.name || "N/A"}`,
      `- **Synonym:** ${props.synonym || "N/A"}`,
      `- **Term Type:** ${props.tty || "N/A"}`,
      `- **Language:** ${props.language || "N/A"}`,
      "",
      `### Drug Relationships`,
      `- **Active Ingredient(s):** ${ingredients.join(", ") || "N/A"}`,
      `- **Brand Names:** ${brandNames.slice(0, 8).join(", ") || "N/A"}`,
      "",
      `### Drug Class (ATC)`,
      atcClasses.length
        ? atcClasses.map(c => `- ${c}`).join("\n")
        : "- ATC classification not available",
      "",
      `### Interoperability`,
      `- RxNorm is the **US standard** for drug naming in EHR/EMR systems`,
      `- RxCUI \`${rxcui}\` can be used to query drug interactions, formulary status, and prescribing data`,
      `- Maps to: **NDF-RT**, **SNOMED CT**, **MeSH**, **DrugBank**, **ATC**`,
      "",
      `_Source: NIH National Library of Medicine RxNav API_`,
    ].join("\n");
  
    return { content: [{ type: "text", text }] };
  }

• index.js:28-34 (helper)

  Shared apiFetch utility used by lookup_rxnorm to call NIH NLM RxNav REST APIs.

  async function apiFetch(url) {
    const res = await fetch(url, {
      headers: { "Accept": "application/json" }
    });
    if (!res.ok) throw new Error(`API error ${res.status}: ${url}`);
    return res.json();
  }