# Pharmaceutical relationships with evidence

Retrieve typed medication relationships and correctly interpret empty responses and regulatory evidence.

Canonical: https://iabula.com/docs/en/relations

## Relationships of a record

GET /v1/medications/{id}/relations returns a data list with typed relationships available for the identified medication. Each relationship includes source and target identifiers, type, direction, evidence and validity dates when available.

```bash
curl --fail-with-body "$IABULA_API_BASE/v1/medications/$IABULA_MEDICATION_ID/relations" \
  --header "X-API-Key: $IABULA_API_KEY"
```

## An empty list describes coverage

> data: [] means IaBula has no approved relationship for that record. It does not imply that no generic, reference or interchangeable medication exists in the market.

The explicit regulatory relationship dataset is not populated in the documented V1 baseline. The route is operational, but consumers must treat empty lists as valid results. HTTP 404 indicates an unknown medication identifier.

## Relationships are not recommendations

Regulatory relationships require traceable evidence. Textual similarity or shared ingredients do not establish interchangeability. The API does not recommend substitution or treatment.

- [Evidence classes](https://iabula.com/docs/en/provenance)
- [Canonical records](https://iabula.com/docs/en/medications)

## GET /v1/medications/{id}/relations

| Parameter | Location | Required | Type and bounds |
| --- | --- | --- | --- |
| id | path | yes | string (uuid) |

| HTTP | Content-Type | Schema |
| --- | --- | --- |
| 200 | application/json | RelationPage |
| 400 | application/json | Problem |
| 401 | application/json | Problem |
| 403 | application/json | Problem |
| 429 | application/json | Problem |
| 500 | application/json | Problem |
| 503 | application/json | Problem |
| 404 | application/json | Problem |
| 422 | application/json | HTTPValidationError |

## OpenAPI contract fields

| Schema.field | Type and bounds | Required |
| --- | --- | --- |
| Evidence.class | string | yes |
| Evidence.source | string \| null | no |
| Evidence.dataset | string \| null | no |
| Evidence.retrieved_at | string (date-time) \| null | no |
| Evidence.source_version | string \| null | no |
| Evidence.source_record_id | string \| null | no |
| Evidence.source_run_id | string \| null | no |
| Evidence.attribute | string \| null | no |
| Evidence.rule_version | string \| null | no |
| HTTPValidationError.detail | array<ValidationError> | no |
| MedicationRelation.id | string (uuid) | yes |
| MedicationRelation.type | string | yes |
| MedicationRelation.source_id | string (uuid) | yes |
| MedicationRelation.target_id | string (uuid) | yes |
| MedicationRelation.direction | string | yes |
| MedicationRelation.evidence | Evidence | yes |
| MedicationRelation.valid_from | string (date) \| null | no |
| MedicationRelation.valid_to | string (date) \| null | no |
| Problem.type | string | yes |
| Problem.title | string | yes |
| Problem.status | integer | yes |
| Problem.code | string | yes |
| Problem.detail | string \| null | no |
| Problem.request_id | string | yes |
| RelationPage.data | array<MedicationRelation> | yes |
| ValidationError.loc | array<string \| integer> | yes |
| ValidationError.msg | string | yes |
| ValidationError.type | string | yes |
| ValidationError.input | object | no |
| ValidationError.ctx | object | no |

## Resources

- [OpenAPI JSON](https://iabula.com/openapi.json)
- [Swagger](https://iabula.com/docs/swagger)
- [Documentation index](https://iabula.com/llms.txt)