When you ask a pharmacist what a unit-dose is you may get a funny look. Actually, you will get a funny look. I know because I asked one of the pharmacists I work with that very question today and she gave me a look that could only be described as a cross between concern and pity. She thought the answer to my question was obvious and who could blame her.
The need to define a unit-dose seems a little silly on the surface. I mean everyone knows what a unit-dose is, right ? Yes and no. It makes perfect sense when one is thinking about a tablet or capsule; one tablet is one unit-dose and one capsule is one unit-dose regardless of the strength. Unbeknownst to the manufacturers they define a unit-dose for you when they package the medication. Unfortunately that isn’t an official definition recognized by the manufacturer or the Food and Drug Administration (FDA). I know because I heard it from straight from the horses mouth during an interview with Jay Crowley of the FDA at the unSUMMIT; see my Tweet here. The issue of what a unit-dose is becomes even more confusing when you move beyond a tablet or capsule and start looking at ointments, creams, aerosols, oral liquids and even injectable medications.
My Tweet on the issue elicited a impassioned plea from Heather Leslie, MD to get some kind of agreement from the FDA on the matter. So that’s exactly what I set out to do. Following his interview I caught up with Jay as he left the unSUMMIT. Crowley is the senior advisor for patient safety at the FDA Center for Devices and Radiological Health, and he had some very interesting things to say. He was more than willing to answer my questions with what little time he had.
I asked Crowley about creating a standardized definition for unit-dose and he thought it was an idea long overdue, but reminded me ever so gently that he couldn’t do anything about it until someone forced the FDA to get involved. During his initial interview at the unSUMMIT Crowley said that the FDA makes every attempt to let things work themselves out and only gets involved when there is a “ market failure †. He recommended that I ask one of the large pharmacy organizations to get involved. I don’t know of many large pharmacy organizations, so I’m going to go with ASHP. I’ll take the recommendation for a standardized definition for unit-dose to the Pharmacy Informatics and Technology Section of ASHP and see what happens.
Comments and recommendations welcome.
Hi Jerry,
Interestingly I’ve just returned home from the ISO TC215 Health Informatics meeting in Rio a couple of days ago. Last week a new work item has been proposed – entitled “Generic Model for Dose Syntax” and proposed by Emma Melhuish from the UK NHS dm+d. This proposal has originated out of work done by the NHS and seeks to incorporate international input in developing a standardised approach to the dosage conundrum.
There is also a separate proposal to harmonise this with other standards bodies, including IHTSDO, HL7 & CDISC, so will potentially be very useful work.
I’m not sure if this ISO proposal can be distributed freely at this point – as it is very early days – but will find out and share if I can. I’m sure that others can get access thru their local national standards organisations.
In the meantime I found the link to this document which I assume is a precursor from 2005 – http://www.dmd.nhs.uk/docs/dose_syntax.pdf.
Will keep you posted…
Cheers
Heather
Another way to engage ASHP is to get one of the California delegates to make a resolution in June. This way it stays visible through the process.
You’re at least two steps ahead of my thoughts Heather, as usual. I ran through the document you linked to and while it covers just about everything else in a valid sig, I don’t see anything about defining a unit dose. I think the unit-dose definition will have to come from a consensus among the manufacturers and tied directly to the NDC. I don’t even know if that’s possible.
Just an FYI – I’m going to take John’s advice and try to engage one of the California delegates at the ASHP Summer Meeting in June. Can’t hurt.
Thanks for the information.
You have my attention, John. Go on ……
I probably would have given you a funny look too, assuming everyone knows what U/D means. I had no idea that there wasn’t a standardized definition.
You make a good point about it’s definition when it comes to bulk items, such as creams, liquids, injectables, etc. But, if they’re packaged/re-packaged to be used as a single, one-time dose, I would personally consider that “unit dose” also.
It’ll be interesting to read what ASHP has to say about your inquiry.
You hit it on the head, Guzzo. The unit of use becomes the unit-dose when we re-package. The problem that was brought to my attention was that we don’t all re-package in the same way, i.e. 250mg/5ml or 500mg/10ml? Which one would be “the” unit-dose? Some would argue, me included, that they’re both a unit-dose.
Thanks for stopping by.
@Jerry Fahrni
From my clinical modelling point of view, 250mg/5ml or 500mg/10ml is the concentration and the unit of dose administration is millilitres. My problem arises when there are multiple ways of representing dose units – quantities are straightforward but the outliers are not. It is when you get into ‘puffs’ and ‘drops’ and ‘1 cm applied sparingly to affected area’ that it gets tricky to apply consistently for computability and thus potential use in calculating medication compliance etc.
Excuse my bad example. You’re right, thanks for pointing that out Heather.
It is interesting that the FDA does not use the term “unit-dose” in their regulation requiring bar coding on medication packages. They use the terms “unit” and “immediate container.”
In my conversations with the FDA officials who held the hearings that led to the bar-code regulation of 2004, they indicated that they deliberately avoided the term “unit dose” because they realized unit doses are determined by physicians in specific relation to the needs of their patients. Thus, when the FDA required bar codes on all drug packages, they referred to these (as they always had in regulating human-readable print) as ‘immediate containers” or “units.”
I think we’d be better off calling manufacturers’ individually packaged pills “single-unit packages.”
The confusion goes back to the unit-dose drug distribution movement in the 60s, when proponents felt it would be helpful if drug mfgs would package down to the pill. Drug manufacturers responded by packing single-units of what became commonly called “unit-dose packages.” While in many instances the “unit-dose” ordered by the physician might match the single-unit package from the manufacturer, there were other instances where the unit-dose ordered would he half of the mfg single-unit packages, or multiples of the packages.
An attempt to clarify terms by introducing “unit of use” only muddied the waters. If you think there is confusion over “unit dose,” ask your colleagues to define “unit of use!” Some will say it is the actual unit used (e.g., administered) and others will say it is the larger unit from which “unit-doses” are extracted for administration.
I’m not sure the term “unit of use” is useful.
In my interactions with the agency, I have been given no reason to believe the FDA will fell it is within their scope of work to official define “unit dose.” I certain they will never define what a “unit-dose” is for each drug. Nor will they dictate to the manufactures what dosages of their drugs should be packaged in single-unit packages.
They will remain firm in regulating what is printed on drug packages down to immediate containers or packaging units.
We attempted to clarify these terms in our Glossary on page 779 of our AJHP article: “Practical guide to bar coding for patient medication safety” See: http://goo.gl/zmC9
Hi Mark – Thanks for the information. It’s interesting that you talk about the nomenclature as it is confusing and certainly inconsistent. You use the term “unit of use” which we use to describe anything we package for immediate use for patients, i.e. 250mg of liquid amoxicillin pulled into a syringe from a bulk bottle, or 15mL of chlorhexidine put in a “unit-dose” cup, etc. I’m not sure that term is useful either. It gets even fuzzier when you start talking about “dispensing units” which is a term often used to describe billing practices.
I received the following from someone at ASHP, which was referred to as current policy: Statement on Unit Dose Drug Distribution – “The unit dose system may differ in form, depending on the specific needs of the organization. However, the following distinctive elements are basic to all unit dose systems: medications are contained in single unit packages; they are dispensed in as ready-to-administer form as possible; and for most medications, not more than a 24-hour supply of doses is delivered to or available at the patient-care area at any time.†Notice the use of “single use packages” phrase that you mention in your comments.
There is also the “ASHP Technical Assistance Bulletin on Single Unit and Unit Dose Packages of Drugs” found here: http://www.ashp.org/DocLibrary/BestPractices/DistribTABUnitDose.aspx – That document also uses “single use packages”. Perhaps we should first standardize the verbiage?
Something to think about is an interesting point made by Dr. Leslie in the comment section of this post: “It is when you get into ‘puffs’ and ‘drops’ and ‘1 cm applied sparingly to affected area’ that it gets tricky to apply consistently for computability and thus potential use in calculating medication compliance etc.” How do we handle such an interesting dilemma? I suppose it’s a good problem to have as everyone is talking about the issue and getting it out in the open. The few conversations I’ve had with you and Dr. Leslie lead me to believe that I have a lot to learn about the subject, as the United States appears to be lagging in several of these areas.
It seems odd to me that something so simple on the surface can become so cloudy. Thanks for stopping by, always appreciate the feedback.
Hi Jerry –
While your at it, how about a formal definition for immediate container. The definitions tell us that a liner is not an immediate container, but I can find no definition of immediate container.
Hi Karl
Others have mentioned that very issue as well. I agree, it’s a problem.
Immediate container to me is the container you have in your hand immediately prior to giving a patient their medication. Unfortunately that varies based on location and practice environment. Gives me a headache just thinking about it. Mark Neuenschwander (http://hospitalrx.com/) has some interesting things to say about it. You two should talk. Thanks for stopping by.