# fittings RxClass Drug Classes

> fittings RxClass Drug Classes is a paid API for AI agents from fittings.sh, paid per call via x402, $0.00498/call, status unknown (last checked 2026-09-14).

Returns deduplicated, labeled drug classification data (therapeutic, pharmacologic, MOA, ATC, VA classes) for a drug or ingredient via NLM RxClass.

## Facts

- Endpoint: GET https://fittings.sh/v1/rxclass/drug-classes
- Price: $0.00498/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/fittings-rxclass-drug-classes-8b29e1ca
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_JhysY2cgIc2slriw7wfKc

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability fittings-rxclass-drug-classes-8b29e1ca
```

Example prompt: What are all the drug classes for warfarin — including its mechanism of action, EPC, ATC, and VA classes — from RxClass?

## When to prefer this

Use this endpoint when you need structured, deduplicated drug classification data (therapeutic, MOA, ATC, VA) sourced directly from NLM RxClass, especially when you want filtered results by class type or relationship source. Prefer it over raw RxClass API calls because it handles deduplication and labeling automatically. It is ideal for enriching drug databases, building clinical decision support tools, or answering pharmacology queries about a specific drug or ingredient.

## Known failure modes

- Drug name not found in RxNorm — returns empty results or 404
- Ambiguous drug name matching multiple RxNorm concepts — may return classes for an unintended concept
- Invalid classTypes or source filter value — returns error or empty set
- RxClass upstream service unavailable — returns 5xx error
- Limit out of range (outside 1-100) — returns validation error

## How this service works

The therapeutic, pharmacologic, mechanism-of-action, ATC and VA classes a drug or ingredient belongs to, from NLM RxClass, deduplicated and labeled.

## Output

A deduplicated list of drug class objects, each labeled with the class name, class type (e.g. EPC, MOA, ATC1-4, VA, SCHEDULE), the relationship source (e.g. MEDRT, RXNORM, VA), and a class identifier — covering therapeutic, pharmacologic, mechanism-of-action, ATC hierarchy, and VA classification schemes for the queried drug or ingredient.

## Request schema (JSON Schema)

```json
{
 "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",
     "required": [],
     "properties": {
      "drug": {
       "type": "string",
       "description": "Drug or ingredient name, e.g. warfarin"
      },
      "limit": {
       "type": "number",
       "description": "Maximum classes, 1-100, default 50"
      },
      "rxcui": {
       "type": "string",
       "description": "RxNorm concept id, as an alternative to `drug`"
      },
      "source": {
       "type": "string",
       "description": "Restrict to one relationship source: ATC, ATCPROD, DAILYMED, FDASPL, FMTSME, MEDRT, MESH, RXNORM, SNOMEDCT, VA"
      },
      "classTypes": {
       "type": "string",
       "description": "Comma-separated class types to keep, e.g. EPC,MOA. One of ATC1-4, CHEM, DISEASE, DISPOS, EPC, MESHPA, MOA, PE, PK, SCHEDULE, STRUCT, TC, VA"
      },
      "includeProducts": {
       "type": "boolean",
       "description": "Also include classes carried only by branded or clinical drug concepts, not just ingredients"
      }
     }
    }
   },
   "additionalProperties": false
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/fittings-rxclass-drug-classes-8b29e1ca/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from fittings.sh](https://www.zero.xyz/host/fittings.sh/llms.txt)