Examples of use of Medication order archetype and associated cluster archetypes
Ian McNicoll, openEHR
Introduction
Medication ordering/prescribing can be highly complex, particularly the combination of dose amounts and timing.
This document contains a number of worked examples which should help inform intended use of the medication order archetype and associated cluster archetypes.
The key archetypes used in the construction of medication orders are …
Medication order: http://openehr.org/ckm/#showArchetype_1013.1.1445
Medication substance: http://openehr.org/ckm/#showArchetype_1013.1.2368
Timing - daily: http://openehr.org/ckm/#showArchetype_1013.1.2245
Timing - repetition: http://openehr.org/ckm/#showArchetype_1013.1.2246
Other cluster archetypes are generally required e.g. Authorisation, dispensing details but these are omitted in these examples for clarity.
An example template which makes use of these archetypes can be viewed at
ePrescription (FHIR): http://openehr.org/ckm/#showTemplate_1013.26.80
The following mindmap outlines the combination of Medication order archetype with its Cluster components, as used in the examples …
Overview of Medication order and related cluster archetypes.
Use of terminology
Terminology is omitted for clarity but it would be expected in most examples, the 'Medication item' would be coded using a reference medication terminology such as RxNorm, dm+d, AMT etc.
Dose and Product-based prescribing
Examples are given for both dose-based and product-based prescribing
Dose-based prescribing
The drug name (Medication item) is expressed as a chemical agent and the dose amount is generally expressed as an SI unit. Route is generally specified rather than form.
e.g. Atenolol - oral - 40mg twice daily
Product-based prescribing
The drug name (Medication item) is expressed as a specific manufactured product (generic or otherwise) and the dose is generally expressed as a dose unit - tablets, capsules, drops, puffs. Form is generally not specified since it is carried in the product name
e.g. Atenolol 40mg tabs - 1 tablet twice daily
Parsable dose syntax examples
Most examples define an equivalent 'parsable dose syntax' intended to carry a subset of dose amount and timing details, appropriate for transferring information between disparate systems. The examples shown are derived from a dose syntax developed by NHS Scotland.
Note that this syntax has no official status within openEHR and is shown here purely as an example.
A. Simple product-based medication order
Atenolol 40mg one tablet in the morning, indefinitely
Medication order
Medication item: Atenolol 40mg tabs
Parsable dose directions: "1 m"
Dose direction..
Direction sequence: 0
Dose pattern..
Pattern sequence: 0
Dose amount: 1
Dose unit: tablet
Timing - daily..
Named time event: in the morning
Direction duration: Indefinitely
B. Simple dose-based medication order
Atenolol 40mg one tablet in the morning for 4 weeks
Medication order
Medication item: Atenolol
Route: oral
Parsable dose directions: "40mg m"
Dose direction..
Dose pattern..
Dose amount: 40
Dose unit: mg
Timing - daily..
Named time event: in the morning
Direction duration: 4 weeks
C. 'As required' order with an 'up to' interval timing and a maximal daily dose
Paracetamol liquid oral 125mg/5ml 5-10ml up to every 4-6 hours as required for pain or fever; maximum 40ml in 24hrs
Medication order
Medication item: Paracetamol liquid 125mg/5ml
Route: oral
Parsable dose directions: "5-10ml ^4h/6h prn [40ml h24]"
Dose direction..
Dose pattern..
Dose amount: 5-10
Dose unit: ml
Timing - daily..
Interval: <= 4-6 hours
As required: True
As required criterion: "for pain or fever"
Medication safety..
Maximum dose..
Maximum amount: 40
Maximum amount dose unit: ml
Allowed period: 24 hours
Notes
The 'up to' aspect of the dose interval is carried in the magnitude_status attribute of the DV_QUANTITY datatype of the openEHR reference model.
D. Tapered dose-based prescribing order
Enalapril - oral - 2.5mg once daily for 1 day, then 5mg once daily for 7 days, then 5 mg at 6pm and 10mg at 10pm, indefinitely
Medication order..
Medication item: Enalapril
Route: oral
Parsable dose directions: "2.5mg od:1d ;5mg od:7d ;5mg @1800 & 10mg @2200 :ind"
Dose direction..
Direction sequence: 0
Dose pattern..
Dose amount: 2.5
Dose unit: mg
Timing - daily..
Frequency: 1/day
Direction duration: 1 day
Dose direction..
Direction sequence: 1
Dose pattern..
Dose amount: 5
Dose unit: mg
Timing - daily..
Frequency: 1/day
Direction duration: 1 day
Dose direction..
Direction sequence: 2
Dose pattern..
Pattern sequence: 0
Dose amount: 5
Dose unit: mg
Timing - daily..
Specific time: 1800
Dose pattern..
Pattern sequence: 1
Dose amount: 10
Dose unit: mg
Timing - daily..
Specific time: 2200
Direction duration: indefinitely
Additional instruction: Avoid grapefruit
D. Tapered product-based prescribing order
Enalapril 2.5mg tablets; 1 tab at night for 2 days, then 1 tab morning and night for 5 days, then 4 tabs at night, indefinitely
Medication order..
Medication item: Enalapril 2.5mg tablet
Parsable dose directions: "1 n:2d ;1 m+n:5d ; 4 n:ind"
Dose direction..
Direction sequence: 0
Dose pattern..
Dose amount: 1
Dose unit: tab
Timing - daily..
Named time event: in the morning
Direction duration: 2 day
Dose direction..
Direction sequence: 1
Dose pattern..
Dose amount: 1
Dose unit: tab
Timing - daily..
Named time event: in the morning
Named time event: at night
Direction duration: 5 day
Dose direction..
Direction sequence: 2
Dose pattern..
Dose amount: 4
Dose unit: tab
Timing - daily..
Named time event: at night
Direction duration: indefinitely
Additional instruction: Avoid grapefruit
E. Complex dose-based order with multiple dose patterns
Gabapentin – oral - 300mg at night for one day, then 300mg in the morning and at night for one day, then 300mg three times a day for one day, then 300mg in the morning, 300mg in the afternoon and 600mg at night for 4 days, then 600mg in the morning, 300mg in the afternoon and 600mg at night for 1 day, then 600mg three times a day indefinitely.
Medication order..
Medication item: Gabapentin
Route: oral
Parsable dose directions: 300mg n:1d;300mg m+n:1d;300mg td:1d;300mg m+pm&600mg n:4d;600mg m&300mg a&600mg n;600mg td:ind"
Dose direction..
Direction sequence: 0
Dose pattern..
Dose amount: 300
Dose unit: mg
Timing - daily..
Named time event: at night
Direction duration: 1 day
Dose direction..
Direction sequence: 1
Dose pattern..
Dose amount: 300
Dose unit: mg
Timing - daily..
Named time event: in the morning
Named time event: at night
Direction duration: 1 day
Dose direction..
Direction sequence: 2
Dose pattern..
Dose amount: 300
Dose unit: mg
Timing - daily..
Frequency: 3 / day
Direction duration: 1 day
Dose direction..
Direction sequence: 3
Dose pattern..
Pattern sequence: 0
Dose amount: 300
Dose unit: mg
Timing - daily..
Named time event: in the morning
Named time event: in the afternoon
Dose pattern..
Pattern sequence: 1
Dose amount: 600
Dose unit: mg
Timing - daily..
Named time event: at night
Direction duration: 4 day
Dose direction..
Direction sequence: 4
Dose pattern..
Pattern sequence: 0
Dose amount: 600
Dose unit: mg
Timing - daily..
Named time event: in the morning
Dose pattern..
Pattern sequence: 1
Dose amount: 300
Dose unit: mg
Timing - daily..
Named time event: in the afternoon
Dose pattern..
Pattern sequence: 2
Dose amount: 600
Dose unit: mg
Timing - daily..
Named time event: at night
Direction duration: 1 day
Dose direction..
Direction sequence: 5
Dose pattern..
Dose amount: 600
Dose unit: mg
Timing - daily..
Frequency: 3 / day
Direction duration: indefinitely
F. Dose-based medication order with use of 'timing repetitions'
Azithromycin - oral - 500 mg once daily three times a week (Mon Wed Fri) for 6 months
Medication order..
Medication item: Azithromycin
Route: oral
Parsable dose directions: "500mg od:6m, tw"
Dose direction..
Direction sequence: 0
Dose pattern..
Dose amount: 500
Dose unit: mg
Timing - daily..
Frequency: 1 / day
Timing - repetition..
Frequency: 3 / week
Specific day of the week: Monday
Specific day of the week: Wednesday
Specific day of the week: Friday
Direction duration: 6 m
G. 'As required' product-based order with specified start date
Paracetamol 500mg tablet 1-2 tablets up to 4-6 hourly as required for knee pain from 1 Dec 2016 for 14 days [Maximum 8 tablets in 24 hrs]. Take with food.
Medication order..
Medication item: Paracetamol 500mg tablet
Parsable dose directions: "1-2 ^h4\h6 prn:7d [8 h24]"
Dose direction..
Dose pattern..
Dose amount: 1-2
Dose unit: tablet
Timing - daily..
Interval: <= 4-6 hr
As required: True
As required condition: for knee pain
Direction duration: indefinitely
Medication safety..
Maximum dose..
Maximum amount: 8
Maximum amount dose unit: tablets
Allowed period: 24 hours
Additional instruction: Take with food
Order details..
Order start date/time: 1 Dec 2016
Notes
The 'up to' aspect of the dose interval is carried in the magnitude_status attribute of the DV_QUANTITY datatype of the openEHR reference model.
H. Complex ‘Ad-hoc’ infusion with administration duration
This is an example of a complex 'ad-hoc' infusion containing a defined ingredient (morphine), a product ingredient (penicillin) and a diluent (saline).
The Medication item name must be generated by the prescriber to reflect the key components of the infusion mixture e.g. to appear on the prescription list or as a label on the infusion itself.
The parsable dose syntax does not cover this use-case and is therefore omitted.
100 mg Morphine liquid (10mg/ml) + 12g Benzylpenicillin (3g powder) in 100ml 0.9% Saline infusion given over 1 hour, starting immediately
Medication order..
Medication item: 100mg Morphine + 12g Benzylpenicillin in 100ml 0.9% Saline infusion
Preparation details..
Substance form: Infusion liquid
Category: Ad-hoc mixture
Ingredient..
Ingredient substance..
Substance name: Morphine
Category: Ingredient
Substance form: liquid for infusion
Strength amount: 10
Strength unit: mg
Diluent..
Diluent amount: 1
Diluent unit: ml
Ingredient amount:10
Ingredient amount unit: ml
Role: Therapeutic
Ingredient..
Ingredient substance..
Substance name: Benzylpenicillin powder for infusion (3g/1ml)
Substance form: powder for infusion
Category: Product
Ingredient amount:12
Ingredient amount unit: g
Role: Therapeutic
Ingredient..
Ingredient substance..
Substance name: 0.9% Saline infusion
Substance form: infusion liquid
Category: Product
Ingredient amount:100
Ingredient amount unit: ml
Role: Diluent
Dose direction..
Dose pattern..
Dose amount: 100
Dose unit: ml
Timing - daily..
Named time event: immediately (stat)
Dose administration duration: 1 hr
Order details..
Order start date/time: 1 July 2016