How

When you send the MedicationStatement resource, you will assign it a logical id.
Reference the logical ID of a previously created Patient resource in the subject field of the MedicationStatement.
A status must be included. See the FHIR R4 spec for the status value set.
Include any other information in the MedicationStatement, using coding when possible.
POST https://<client>.fhir-api.sandbox.patientsknowbest.com/fhir/MedicationStatement

Very basic MedicationStatement resource example (no coding):

{
  "resourceType": "MedicationStatement",
  "id": "<Client assigned patient logical id>",
  "status": "stopped",
  "medicationCodeableConcept": {
    "text": "FCR (fludarabine-cyclofosfamide-rituximab)"
  },
  "subject": {
    "reference": "Patient/<Client assigned logical id for Patient resource>"
  },
  "effectivePeriod": {
    "start": "2024-10-22",
    "end": "2024-12-22"
  },
  "dateAsserted": "2024-10-22"
}

Very basic MedicationStatement resource example (with coding):

{
  "resourceType": "MedicationStatement",
  "id": "<Client assigned patient logical id>",
  "status": "active",
  "medicationCodeableConcept": {
    "coding": [
            {
                "system": "http://snomed.info/sct",
                "code": "776550005",
                "display": "Lisinopril"
            }
    ],
    "text": "Lisinopril 40 mg tablet"
  },
  "subject": {
    "reference": "Patient/<Client assigned logical id for Patient resource>"
  },
  "effectivePeriod": {
    "start": "2018-10-03"
  },
  "dosage": [
    {
      "text": "Take 40 mg tablet once daily",
      "timing": {
        "repeat": {
          "frequency": 1,
          "period": 1,
          "periodUnit": "d"
        }
      },
      "doseAndRate": [
        {
          "doseQuantity": {
            "value": 1,
            "unit": "tablet",
            "system": "http://unitsofmeasure.org",
            "code": "tablet"
          }
        }
      ]
    }
  ]
}

Creating MedicationStatements

How