RAS^O17 — Pharmacy/Treatment Administration

The message that notifies the actual administration of a medication or treatment to a patient. Pivot of the hospital medication chain: from prescription to dispensing to bedside administration.

Purpose of the message

RAS^O17 is triggered every time a caregiver actually administers a medication or treatment to a patient. It documents:

• the administered drug (with RxNorm / SNOMED CT / national codification);
• the actual administered dose (may differ from prescribed, e.g. partial refusal);
• the route of administration (PO, IV, IM, SC, etc.);
• the administration timestamp;
• the administering caregiver;
• the lot and expiry date (for pharmacovigilance and traceability);
• associated clinical observations (pre/post administration vital signs).

Typical use cases: bedside administration with barcode scan on a nurse tablet, ICU infusion, hospital antibiotic therapy, oncology chemotherapy. The RAS^O17 is generated by the nurse PDA or oncology software, then pushed to the EHR for traceability.

Segment structure

Per HL7 v2.5.1 chapter 4, the RAS_O17 structure is:

RAS_O17
  MSH                        Message Header (mandatory)
  [ { NTE } ]                Notes / comments
  [ PATIENT
      PID                    Patient Identification
      [ PD1 ]                Patient Additional Demographics
      [ { NTE } ]            Notes
      [ { AL1 } ]            Allergy Information
      [ PATIENT_VISIT
          PV1                Patient Visit
          [ PV2 ]            Patient Visit - Additional Info
        ]
    ]
  [ { ORDER
      ORC                    Common Order (mandatory in group)
      [ TIMING
          TQ1                Timing/Quantity (v2.5+)
          [ { TQ2 } ]
        ]
      [ RXO ]                Pharmacy/Treatment Order (from original prescription)
      [ { NTE } ]
      [ { RXR } ]            Pharmacy/Treatment Route
      [ { COMPONENT
          RXC                Pharmacy/Treatment Component Order
          [ { NTE } ]
        }]
      { ADMINISTRATION
          RXA                Pharmacy/Treatment Administration (mandatory)
          [ RXR ]            Route
          [ { OBSERVATION
              OBX            Observation/Result
              [ { NTE } ]
            } ]
        }
    } ]

MSH — Message Header

• MSH-9: RAS^O17^RAS_O17.
• MSH-10: unique message identifier.
• MSH-11: P (Production), T (Test).
• MSH-12: 2.5.1.

PID — PV1

Patient identification (PID) and visit (PV1) — see ADT^A01 for detail. Must exactly match the target patient (otherwise risk of medication error on wrong patient).

ORC — Common Order

Links the RAS to the originating prescription. Critical fields:

• ORC-1: order control (RE = Observations to follow, CM = Order is completing). For an actual administration RAS, usually RE.
• ORC-2: placer order number (source prescription number).
• ORC-3: filler order number (pharmacy / care unit number).
• ORC-12: ordering provider (XCN).

RXA — Pharmacy/Treatment Administration

The central segment: what was actually administered.

• RXA-1: Give Sub-ID Counter (0 for initial sequence).
• RXA-2: Administration Sub-ID Counter (incremented for multiple doses).
• RXA-3: Date/Time Start of Administration (CCYYMMDDHHMMSS).
• RXA-4: Date/Time End of Administration (for infusions, may differ from RXA-3).
• RXA-5: Administered Code (CE) — drug code. RxNorm in US, UCD/CIP in France, ATC globally.
• RXA-6: Administered Amount.
• RXA-7: Administered Units (UCUM).
• RXA-15: Substance Lot Number (administered drug lot — critical for pharmacovigilance).
• RXA-16: Substance Expiration Date.
• RXA-17: Substance Manufacturer Name.
• RXA-20: Completion Status (CP = Complete, RE = Refused, NA = Not Administered, PA = Partially Administered).

RXR — Pharmacy/Treatment Route

Describes the administration route:

• RXR-1: Route. Table 0162: PO = Oral, IV = Intravenous, IM = Intramuscular, SC = Subcutaneous, SL = Sublingual, RC = Rectal, TO = Topical.
• RXR-2: Site. Table 0163 (anatomical site).
• RXR-3: Administration Device.

OBX — Observation/Result

Pre- or post-administration clinical observations: BP, heart rate, VAS pain score, glucose. Enables tracking of administration effect.

Real example

Oral amoxicillin 500 mg administered to John Doe in ICU at 14:30:25 by Dr Smith, followed by vital sign observations (BP, respiratory rate):

MSH|^~\&|PHARM|HOSP01|EHR|HOSP01|20260514143025||RAS^O17^RAS_O17|MSG00001234|P|2.5.1|||AL|NE
PID|1||MRN567890^^^HOSP^MR||DOE^JOHN^A^^MR.||19720515|M
PV1|1|I|ICU^101^A^HOSP01|||||DRSMITH^Smith^James^A^^DR.|||||||||VIP123|ADM
ORC|RE|RX2026001|FIL2026001||CM||||20260514143025|||DRSMITH^Smith^James^A^^DR.
RXA|0|1|20260514143025|20260514143025|729^AMOXICILLIN 500MG^RXN|500|MG^^UCUM|||||||||EM0477|20261130||LOT0477^Pfizer^L|||1
RXR|PO^Oral^HL70162
OBX|1|NM|55284-4^Blood pressure^LN||120/80|mm[Hg]^mm[Hg]^UCUM|90-140|N|||F
OBX|2|NM|9279-1^Respiratory rate^LN||16|/min^/min^UCUM|12-20|N|||F

• RXA — amoxicillin 500 mg (RxNorm 729), administered at 14:30:25, lot EM0477, expiry November 2026.
• RXR — oral route (PO).
• OBX 1-2 — BP 120/80 and respiratory rate 16/min post administration.

Acknowledgement

The receiving EHR acknowledges with ACK^O17:

MSH|^~\&|EHR|HOSP01|PHARM|HOSP01|20260514143026||ACK^O17^ACK|ACK00001234|P|2.5.1
MSA|AA|MSG00001234

Common errors

• Empty RXA-15 — without a lot number, impossible to respond to a product recall or pharmacovigilance signal.
• RXA-5 without coding — a free-text drug code prevents CDSS and automated billing. Always carry the RxNorm/UCD code with its namespace.
• Malformed UCUM units — bare mg is ambiguous. Use mg^^UCUM with namespace for conversion.
• RXA-3 ≠ actual time — the timestamp must be the actual administration time, not the data entry time. Systematic drift distorts quality metrics.
• No link to the prescription — without ORC-2 (placer order number), the EHR cannot match the administration to its source prescription.
• Missing RXA-20 — without Completion Status, you can't distinguish a complete, partial or refused administration.

FHIR equivalent

In FHIR R5, RAS^O17 maps to MedicationAdministration. Main mappings:

• PID → Patient
• PV1 → Encounter
• ORC → MedicationAdministration.request → MedicationRequest
• RXA → MedicationAdministration (medication, dosage, effective)
• RXA-15/16/17 → MedicationAdministration via lot, expirationDate, manufacturer (with extension)
• RXR → MedicationAdministration.dosage.route
• OBX → Observation

See also ORM^O01 for the prescription message preceding RAS^O17 in the medication chain.