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A Caution against the Presumption that Product-Based Prescribing is a Panacea

  • Writer: Kyle
    Kyle
  • Jul 10
  • 9 min read

Updated: Jul 11

Blog Written by Louisa Conlon - EHR Pharmacy Lead at HCA Healthcare UK
Blog Written by Louisa Conlon - EHR Pharmacy Lead at HCA Healthcare UK

Dose-base prescribing is the traditional approach to Electronic Health Record (EHR) medication ordering. This is likely because it’s familiar from paper-based systems, e.g. a handwritten ‘paracetamol 1g QDS’ prescription on a drug chart changes little when ordered on an Electronic Prescription and Administration (EPMA) dose-based system, and this familiarity enables easier change management on initial EPMA implementation.

 

However, though more efficient for medical colleagues, dose-based prescriptions require clinician translation into the most appropriate product to supply and administer. Thus, an additional task and a potential clinical hazard, especially in the context of parenteral infusions for preparation in the clinical area for which there are varying strength products available.

 

The alternative is product-based prescribing, i.e. ‘paracetamol 500mg tablets, 2 tablets QDS’. There are numerous advantages associated with product-based prescriptions, as Kyle points out in his ‘Considering the Shift to Product-Based Prescribing: Future Proofing EMPA in Hospitals’ blog published 11/04/25. Key benefits are the facilitation of integration at the care interfaces (Electronic Prescription Service (EPS) and GP Connect), pharmacy inventory systems and automation, and of Closed Loop Medication Administration (CLMA).

 

Yet there are significant disadvantages and they are not often visible to the naked eye. Given the resources required to rebuild an EPMA system from dose- to product-base prescribing or visa versa, the risks, as well of the benefits, of switching must be well known, assessed, mitigated and/or accepted prior to commencing the reconfiguration.

 

Thus, in this blog post I outline these risks and caution against presuming product-based prescribing is a panacea.


 


Reasons to be cautious with product-based EPMA

 


  1. Product build

 

The configuration of the drug dictionary or catalogue must be carefully considered from the perspective of both clinical impact and inventory management. The decision of which dm+d concept level to build at is significant, particularly if the EPMA part of the EHR system is directly linked with the supply side.

 

Building at VMP level (‘nifedipine 30mg modified-release tablets’) may seem most appropriate until a product available in many pack sizes is considered. Then VMPP level (‘nifedipine 30mg modified-release tablets 28 tablets’ or ’‘nifedipine 30mg modified-release tablets 30 tablets’) becomes more appropriate from a procurement and inventory management perspective. Yet AMPP level (‘adalat LA 30mg tablets (Bayer Plc) 28 tablets’) may also be required for narrow therapeutic index medication that must be prescribed by brand for clinical safety.

 

The impact of build level on the visibility, and thus usability, of procurement contracts and lowest product pricing (as well as cost to patient/payor in the independent sector) must not be overlooked.

 


  1. Product order availability

 

The medication product dictionary/catalogue must be carefully managed to reflect the products actually available in the organisation. This requires considerable resources from both the system back end and operational front line.

 

The most common set up for an EHR medication order look-up is for all formulary medication to be available to order (i.e. prescribe) in all organisational facilities and clinical areas, with the exception of particularly higher risk products e.g. ICU only infusions or specialist products for use in particular patient cohorts, e.g. clinical trials, only available on the order look-up in those locations. These exceptions alone can create significant build management work for the EPMA team.

 

When a product becomes unavailable to procure from suppliers, prescribers must be advised of the issue and alternative, and the unavailable product removed from the order look-up. This is challenging as the product may still be physically available in some parts of the organisation in small amounts. Additionally patients may be currently prescribed the product. Thus a co-ordinated back end order look-up removal and prescription switch must occur in liaison with front line Pharmacy staff removal of any remaining product and replacement with the alternative. If done poorly or not at all, patients risk missing doses or having administered an incorrect product/dose.

 

The impact of any misalignment of product order availability on the look-up and physical product lack of availability or visa versa may result in patient harm and alignment requires significant informatics and operational resources.



  1. Product selection

 

The prescriber must be adequately trained to accurately select the most appropriate product and understand the impact of inappropriate product selection.

 

A product-based drug order look-up for oral amoxicillin may appear like:

  • amoxicillin 250 mg capsules

  • amoxicillin 500 mg capsules

  • amoxicillin 125 mg/ 5 mL powder for oral suspension

  • amoxicillin 250 mg/ 5 mL powder for oral suspension

 


To order a dose of amoxicillin 500 mg every 8 hours, a prescriber must consider:

 

  1. Product strength: the prescriber may be inclined to select the first product on the order look-up for efficiency, i.e. amoxicillin 250mg capsules, however, the second product on the order look-up, i.e. amoxicillin 500mg capsules, is most appropriate from a clinical (reduced capsule burden to the patient) and economic (reduced cost to the organisation) perspective.

 


To order the same dose In a patient with swallowing difficulties, the prescriber must also consider:

 

  1. Product formulation: the prescriber may be inclined to select the capsule product, i.e. ‘amoxicillin 500 mg capsule’ as it is the strength most aligned with the dose, however, ‘amoxicillin 250 mg/ 5 mL powder for oral suspension’ is most appropriate from a formulation perspective and most safe with a dose of ‘500 mg (10 mL)’ clearly visible on the order.

 


The impact of poorly trained prescribers or inappropriate order selection can result in challenges for the clinicians supplying and administering the dose and confusion may result in a compromise to patient care or safety. It is often pharmacists verifying orders that pick up on and remediate product mis-selection which then calls into question whether this remediation is prescribing and in the scope of their practice.

 

Furthermore, product mis-selection can cause a propagation of issues throughout a patient stay. For example, if an incorrect product is selected on admission as part of the drug history, and that product then reconciled to the visit medication and later reconciled to the discharge medication, it results in significant remediation requirements across a variety of medication workflows to prevent potential harm.

 


  1. Dose equivalency

 

The EHR must have a dose equivalency function to enable product-based prescribing in the UK context to truly work safely and appropriately for patients. Dose equivalency is the ability of the system to understand and recognise that two ‘ramipril 2.5mg tablets’ are equivalent in dose to one ‘ramipril 5mg tablet’.

 

Even with appropriate product order availability and product selection, the UK supply chain is such that shortages of medications occur frequently and often without much notice. It is often the case that an alternative product to that prescribed is all that is available in the acute situation and thus must be administered - the EPMA system needs to facilitate this without confusing or causing concern with front line clinicians nor undermining its own credibility.

 

The dose equivalency functionality must be configured for each product algorithmically - i.e. ramipril 5mg = ramipril 2.5mg x 2 = ramipril 1.25mg x 4 etc - and this process must be as robustly governanced for assurance as for any other part of the medication configuration. If the need or desire for partial product dose equivalency - i.e. half a ‘ramipril 10mg tablet’ is equivalent to one ‘ramipril 5mg tablet - exists, then the appropriateness of every partial product must be clinical reviewed and risk assessed adding additional resource skillset and time requirements to build.

 

Dose equivalency must also be compatible across interfaces, e.g. between the EHR and integrated Automated Dispensing Cabinets (ADCs). This is particularly important where ADCs are profiled, i.e. the ADCs are configured to receive medication orders for specific patients from the EHR and as a result only enable physical access by clinicians to the medications prescribed. Additionally, dose equivalency must facilitate Closed Loop Medication Administration (CLMA) through recognition of appropriate dose equivalent barcodes on scanning at the bedside at administration.

 

The impact of a lack of dose equivalency in product-based prescribing EPMA in the UK context is so significant that it renders the system not fit for purpose. Where dose equivalency does exist, it creates additional build demand on informatics resources that may not have been anticipated.

 


  1. Multi-component configuration

 

The EPMA system must enable medication orders to be configured with multiple product components, not simply a single product.

 

In its simplest guise, multi-component orders are those where multiple products are required to administer the dose of the medication order, e.g. as levothyroxine is available as 25 mcg tablet, 50 mcg tablet and 100 mcg tablet products, a dose of ‘levothyroxine 175 mcg OD’ should be supplied and administered as one ‘levothyroxine 100 mcg tablet’, one ‘levothyroxine 50 mcg tablet’ and one  ‘levothyroxine 25 mcg tablet’ (this combination in particular for minimal tablet burden and multiple tablet risk of confusion) and thus, the medication order for ‘levothyroxine 175 mcg OD’ should be configurable in the system from multiple products.

 

A parenteral example of this is intravenous immunoglobulin (IVIG) - a product-based prescription of a 17.5g dose of IVIG is most appropriately administered using one ‘10 g vial’, one ‘5 g vial’ and one ‘2.5 g vial’ consecutively as any other combination would result in excessive vial burden (increased risk of error and antibacterial contamination of the line) or inappropriate waste of a limited and costly medication. 

 

As a result, a product-based prescribing system must have the functionality to configure multiple products to an order. Without such all products required to administer the dose must be deduced by clinicians. Even with this deduction the EHR must also support the supply or administration of all necessary component products through the dispensing and administration documentation functionalities. Without multiple component configuration for ordering, supply and administration, product-based prescribing is not effective and may result in clinical harm.

 

An additional challenge in the UK linked to multi-component configuration is the preparation of parenterals. The IVIG above is a rare example of a ‘ready-to-administer’ product - i.e. requires no preparation in the form of mixing or compounding before administration - even if multiple vials need to be administered consecutively to deliver the required dose. This is unlike the majority of parenteral infusions on the UK market which require reconstitution of a solid or a concentrated liquid in a base IV fluid. Most often this preparation is done by the nursing team in the clinical area (rather than by the pharmacy team in the aseptic unit with the exception of Systemic AntiCancer Treatment (SACT)).

 

Infusion preparation requires multiple components, for example, ‘clarithromycin 500 mg in sodium chloride 0.9% 250 mL infusion’ order is made up of the active drug product (clarithromycin 500 mg powder for concentrate for solution for infusion vial), a diluent product (water for injections 10 mL) and a base product (sodium chloride 0.9% 250 mL). The product-based EPMA system must facilitate the prescription of the infusion (clarithromycin 500 mg in sodium chloride 0.9% 250 mL infusion) whilst also enabling dispensing of the individual component products (clarithromycin 500 mg powder for concentrate for solution for infusion vial, water for injections 10 mL and sodium chloride 0.9% 250 mL) - where the drug dictionary/catalogue is the direct one-to-one product link between the clinical prescription and the inventory management supply system this does not compute. Instead the EHR must have the functionality to map the medication order to the components required to administer it.

 

What are more challenging again for product-based prescribing EPMA systems are concentration-based (e.g. vancomycin) and weight-based (e.g. rituximab) infusions - the vast number of doses of which are possible (a range for the former and infinite for the latter) makes a connected clinical and supply functionality via a single, product-based drug dictionary/catalogue nigh on impossible without further, complex build of additional configuration to make the EHR fit for purpose for UK workflows. Moreover, the EHR should be able to differentiate the infusion components already available in the clinical area (most diluents and fluids are stocked on most wards) and those that are required from dispensary and communicate such.

 


EHRs that try to facilitate both the clinical medication context (i.e. dose-based prescriptions) and the supply scenario (i.e. product-based prescribing) by direct connection through a single drug dictionary or catalogue fail to understand the complexity of the UK medication management. An environment where not all product forms or strengths are stocked or available in an organisation let alone a clinical area, where there are frequent, prolonged product shortages, and where the majority of parenteral infusions are not supplied as ready-to-administer products thus requires clinician preparation near the bedside. As a result, EPMA systems must enable medication orders to be configured with or smartly mapped to multiple product components otherwise it leads to, at best, a suboptimal system that end-users make work through sheer perseverance, time and energy, and at worst, a system that clinicians workaround in order to deliver safer care.

 


So whilst product-based prescribing may facilitate of integration at care interfaces, pharmacy inventory systems and automation, and Closed Loop Medication Administration, caution must be taken with presuming it is a EPMA panacea for the reasons of product build, product order availability, product selection, dose equivalency and multi-component orders.

 
 
 

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