{"uid":"cap_uIqgegxYDEXHsyMkcfl_w","slug":"cms-nadac-drug-acquisition-cost-changes-feed-8b75df91","name":"CMS NADAC Drug Acquisition Cost Changes Feed","description":"Which drug acquisition costs changed this week? NADAC per-unit cost changes and NDCs added or dropped, with CMS’s stated reason, 2025 on, from CMS’s weekly NADAC files. Updated weekly. $0.05 per call (x402, USDC on Base); 3 free calls a day.","url":"https://data.spencermcw.com/v1/drug/nadac/changes?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET"],"type":"string"},"queryParams":{"type":"object","properties":{"ndc":{"type":"string","pattern":"^(\\d{11}|\\d{4,5}-\\d{3,4}-\\d{1,2})$"},"week":{"type":"string","pattern":"^\\d{4}-\\d{2}-\\d{2}$"},"field":{"enum":["nadac_per_unit","listed"],"type":"string"},"limit":{"type":"integer","maximum":100,"minimum":1},"since":{"type":"string","format":"date-time","pattern":"^(?:(?:\\d\\d[2468][048]|\\d\\d[13579][26]|\\d\\d0[48]|[02468][048]00|[13579][26]00)-02-29|\\d{4}-(?:(?:0[13578]|1[02])-(?:0[1-9]|[12]\\d|3[01])|(?:0[469]|11)-(?:0[1-9]|[12]\\d|30)|(?:02)-(?:0[1-9]|1\\d|2[0-8])))T(?:(?:[01]\\d|2[0-3]):[0-5]\\d:[0-5]\\d(?:\\.\\d+)?(?:Z|([+-](?:[01]\\d|2[0-3]):[0-5]\\d)))$"},"cursor":{"type":"string","pattern":"^\\d{1,12}$"}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","properties":{"data":{"type":"object","required":["records","next_cursor"],"properties":{"records":{"type":"array","items":{"type":"object","required":["id","as_of","ndc","description","field","old","new","effective","reason","detected_at","source_sha256_old","source_sha256_new","method_version"],"properties":{"id":{"type":"string"},"ndc":{"type":"string"},"new":{"type":["string","null"]},"old":{"type":["string","null"]},"as_of":{"type":"string","description":"The weekly file the change first appears in."},"field":{"enum":["nadac_per_unit","listed"],"type":"string"},"reason":{"type":["string","null"],"description":"CMS’s primary reason, from the NADAC Comparison file."},"effective":{"type":"string"},"description":{"type":"string"},"detected_at":{"type":"string"},"method_version":{"type":"string"},"source_sha256_new":{"type":["string","null"]},"source_sha256_old":{"type":["string","null"]}},"additionalProperties":false}},"next_cursor":{"type":["string","null"]}},"additionalProperties":false}}}}}}},"responseSchema":null,"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.05","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.05/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.05","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.05","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_9k9EeZfySiLu2xK519nHU","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.05","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Returns weekly changes in CMS NADAC per-unit drug acquisition costs and NDC listing status changes, with CMS's stated reason for each change.","exampleAgentPrompt":"What drug acquisition cost changes did CMS publish in the NADAC file for the week of 2025-06-09? Show me up to 25 records and include the reason CMS gave for each change.","exampleUseCases":[{"title":"Weekly drug price change monitoring","prompt":"Pull all NADAC per-unit cost changes from CMS for the week of 2025-06-02 — I want to see which drugs went up or down and what reason CMS listed for each one."},{"title":"Track listing changes for a specific NDC","prompt":"Has NDC 00069-0105-01 had any NADAC listing status changes in 2025? Show me when it was added or dropped and what CMS's reason was."},{"title":"Alerting pipeline for cost spikes","prompt":"Give me all NADAC cost changes detected since 2025-05-01T00:00:00Z, up to 100 records, so I can flag any drugs whose per-unit cost jumped this month."}],"resultDescription":"A paginated list of NADAC change records, each containing the NDC, drug description, the changed field (nadac_per_unit or listed), old and new values, the effective date, the weekly CMS file the change first appeared in, CMS's stated reason, detection timestamp, method version, and source file SHA256 hashes for auditability. A next_cursor value is provided for pagination.","failureModes":["Invalid NDC format returns a validation error","Invalid week date format returns a 400 error","Exceeding limit of 100 returns a validation error","No data available for a given week if CMS has not yet published that file","Malformed since datetime returns a parsing error","Payment failure (x402) if USDC on Base is not provided and free daily quota is exhausted"],"whenToPreferThis":"Use this endpoint when you need a structured, paginated change log of CMS NADAC drug acquisition costs — specifically to detect which drugs changed price or listing status week-over-week, and why. Prefer this over the raw NADAC lookup endpoint when your goal is delta detection, auditing, or alerting on cost changes rather than looking up the current cost for a specific drug.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-23T12:30:17.057Z","isFirstParty":false,"canonicalSlug":"cms-nadac-drug-acquisition-cost-changes-feed-8b75df91"}