IE Medication Events Implementation Guide
0.1.0 - Nostalgic IE (draft) Ireland flag

IE Medication Events Implementation Guide - Local Development build (v0.1.0) built by the FHIR (HL7® FHIR® Standard) Build Tools. See the Directory of published versions

Dosage

Guidance. How to express a dosage with the IE MPD Dosage profile, used by the ePrescription item, the eDispensation and the medication statement (ADR-004). The structure follows the UK Core medicines implementation guide's Dosage guidance; the rules map to HIQA EP Section 5 (September 2026 draft).

Principles

  • Always give the text. text is the full instruction a person reads (HIQA EP 5.1). Structured elements add to it, never replace it (ie-dos-1).
  • Code what you can. Routes, sites, methods and additional instructions use SNOMED CT. Quantities use a SNOMED CT unit of presentation for product-based doses (732936001 Tablet, 732937005 Capsule, 732981002 Actuation) or UCUM for strength-based doses (mg, mL, [iU]).
  • One Dosage per scheme. Use sequence to order schemes; schemes in force at the same time share a number.

Elements, in order

# Element HIQA EP How to use it
1 sequence 5.2.1 1, 2, 3 for consecutive schemes (e.g. a loading dose then maintenance); the same number for schemes that apply together (e.g. insulin at each meal)
2 text 5.1 The complete instruction, always present
3 additionalInstruction — Coded supplementary instructions: 311504000 With or after food; 311501008 Half to one hour before food; 421984009 Until finished
4 patientInstruction 5.2.2 Plain-language instruction for the patient (Required)
5 timing.repeat 5.2.4 frequency per period + periodUnit (5.2.4.3; both Mandatory, ie-dos-2); boundsDuration or boundsPeriod for how long (5.2.4.1); duration for how long each administration lasts (5.2.4.2); dayOfWeek (5.2.4.4); timeOfDay (5.2.4.5); when + offset for an event such as ACM before breakfast or HS at bedtime (5.2.4.6)
6 asNeeded[x] 5.2.5 asNeededBoolean = true. HL7 Europe MPD allows only the boolean, so the reason goes in text and patientInstruction; give maxDosePerPeriod (ie-dos-3)
7 site 5.2.6 SNOMED CT body structure, post-coordinated for laterality and qualifiers, or site.text
8 route 5.2.7 SNOMED CT route (e.g. 26643006 Oral, 34206005 Subcutaneous, 47625008 Intravenous, 447694001 Respiratory tract). EDQM binding pending
9 method — SNOMED CT administration method, when the route alone is not enough
10 doseAndRate 5.2.3 doseQuantity (5.2.3.1.1) or doseRange with both ends (5.2.3.1.2, ie-dos-4); rateQuantity or rateRatio for infusions (5.2.3.2)
11 maxDosePerPeriod, maxDosePerAdministration — Upper limits, e.g. 8 actuations in 24 hours

Worked examples

Each example is a validated resource; the structured dosage is shown in its JSON view.

Pattern Instruction Key elements Example
Consecutive schemes Warfarin: 2 tablets once a day for 2 days, then 1 tablet once a day sequence 1 and 2; boundsDuration 2 d; doseQuantity 2 then 1 Tablet warfarin
Concurrent schemes Insulin aspart: 6 units before breakfast, 4 before lunch, 8 before the evening meal three dosages, all sequence 1; when ACM, ACD, ACV; [iU] insulin
As needed, dose range, maximum Salbutamol: 1 to 2 puffs when required for wheeze, max 8 in 24 hours asNeededBoolean; doseRange 1–2 Actuation; maxDosePerPeriod 8 / 24 h salbutamol
Time-bounded course Amoxicillin: 1 capsule three times a day for 5 days, finish the course frequency 3 / 1 d; boundsDuration 5 d; 421984009 Until finished amoxicillin
With food Metformin: 1 tablet twice a day with or after food frequency 2 / 1 d; 311504000 With or after food metformin
Linked to an event Omeprazole: 1 capsule once a day before breakfast when ACM; 311501008 Half to one hour before food omeprazole
Named weekday Methotrexate: 4 tablets once a week on Mondays frequency 1 / 1 wk; dayOfWeek mon; explicit patientInstruction methotrexate

The scenario prescriptions also carry structured dosage, e.g. scenario 1.

Safety notes

  • A dosage that cannot be structured safely (e.g. "as directed by the clinic", sliding scales) is given as text only.
  • High-risk weekly medicines (e.g. methotrexate) name the day in dayOfWeek and in patientInstruction.
  • Do not use UCUM annotations such as {tablet} for product-based doses; use the SNOMED CT unit of presentation.
  • An infusion gives the rate (rateQuantity, e.g. mL/h) and, where relevant, the duration of each administration (timing.repeat.duration).

Not covered

Dose calculation (per kg, per m²), titration rules and dose checking are clinical-system functions, not part of the exchange format.