# ClinicalTrials.gov Search API

> ClinicalTrials.gov Search API is a paid API for AI agents from api.vextorium.com, paid per call via x402, $0.003/call, status unknown (last checked 2026-10-29).

Searches ClinicalTrials.gov for clinical trials by disease, drug, or sponsor and returns structured trial metadata including NCT ID, status, phase, conditions, interventions, sponsor, dates, enrollment, and countries.

## Facts

- Endpoint: POST https://api.vextorium.com/ensayos-clinicos-pago?utm_source=zero.xyz
- Price: $0.003/call
- Payment: x402
- Status: unknown
- Last checked: 2026-10-29
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/clinicaltrials-gov-search-api-003ce2ae
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_AfCTm1rwpAIZXHemWoK-3

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 clinicaltrials-gov-search-api-003ce2ae -d '<json body>'
```

Example prompt: Search ClinicalTrials.gov for recruiting trials on non-small cell lung cancer — show me up to 10 results with their NCT IDs, phases, sponsors, and countries.

## When to prefer this

Use this endpoint when you need structured, machine-readable clinical trial data from ClinicalTrials.gov without building a direct integration. Ideal for agents that need to surface recruiting trials for patients, perform competitive intelligence on sponsors, or track drug development pipelines. Prefer this over manual ClinicalTrials.gov browsing when you need filterable, structured output with enrollment and geographic data in a single call.

## Known failure modes

- No trials found for the given search term — returns empty array with total of 0
- Invalid status enum value — request rejected with validation error
- ClinicalTrials.gov API unavailability — upstream timeout or error
- Misspelled disease/drug name returns no results or unrelated trials
- Very broad search terms may hit result limits and miss relevant trials

## How this service works

Clinical trials on ClinicalTrials.gov by disease, drug or sponsor: title, NCT id, status, phase, conditions, interventions, sponsor, dates, enrollment and countries; recruiting ones by default.

## Output

Returns a JSON object containing the search query, total count, status filter used, data source attribution, and an array of trial objects. Each trial includes: NCT ID, title, status, phases array, conditions array, interventions array, sponsor, start date, estimated end date, enrollment count, countries array, and a direct ClinicalTrials.gov link.

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "buscar": {
   "type": "string"
  },
  "estado": {
   "enum": [
    "reclutando",
    "activos",
    "completados",
    "todos"
   ],
   "type": "string"
  },
  "limite": {
   "type": "integer"
  }
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/clinicaltrials-gov-search-api-003ce2ae/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from api.vextorium.com](https://www.zero.xyz/host/api.vextorium.com/llms.txt)