Why is insulin drawn clear to cloudy?

[Cell-Nurse]

I have a question for my fellow nurses, one I have had since nursing school. A question I have asked fellow nurses throughout my nursing career with no answer to my question.

A simple question of why, when drawing up two different insulin's is the clear(regular) drawn up before the cloudy (nph, lantus, etc.)?

Is there any evidence based reasoning to this practice?

From what I can understand, it is done so that the regular insulin is not contaminated by the cloudy insulin.

IMO however, cloudy should be drawn up first. If I contaminate the clear insulin I will actually be able to visually tell because the bottle of clear insulin will turn cloudy. Yes, this means the bottle is now contaminated & must be disposed of but I much rather dispose of a bottle of insulin than give my patient the wrong dosage of medicine or NPH that was contaminated by regular insulin that I am unable to tell since I could pump a whole syringe full of regular into NPH & no-one would ever be able to tell.

Also, regular is rapid onset & hits the body much harder & faster than the longer acting NPH. If a patient was to get a few extra units of NPH, likely the patient would be no worse for wear. At best, I might have to babysit them for a shift & monitor their levels. However, depending on a patients insulin sensitivity. 1-3 units of regular can drop a patient by 50-150.

Maybe another nurse can help me out, because the best answer I have gotten is "its just the way it is done" I would really like to know the reasoning behind it. Thank's

[loriangel14, RN]

I had a patient recently that we mixed the insulins for but I haven't had many.

[TheCommuter, BSN, RN]

Does anyone have any peer reviewed publications that I could read regarding this topic?

You could have used Google Scholar or any other database to find the peer-reviewed articles yourself.

Forum for Injection Techniques, India: The First Indian Recommendations for Best Practice in Insulin Injection Technique[h=3]Mixing Insulin[/h]For a mixed dose, care should be taken to follow the right sequence of mixing. Regular insulin should be filled first followed by NPH Insulin. Reversal can cause impurities in the regular insulin vials.

http://www.diabetesoutreach.org.au/clinicalpractice/InsulinAdministrationInHosp_Final_Apr%202015.pdf

clear insulin (rapid acting) is to be drawn before cloudy (intermediate acting) to prevent contamination of clear insulin with the cloudy insulin

Diabetes in Elderly | Sharma | Journal of Endocrinology and Metabolism

Mixing may compromise efficacy as physiologic response to mixture of insulin is not the same as compared to the response to individual agent... While mixing short/rapid acting insulin with intermediate insulins, the clear short acting insulin should be drawn first.

[MunoRN, RN]

I think the OP was asking why we do it that way, and nobody has really answered that, just that we do it that way.

It's not to avoid potential harm that could occur by accidently injecting some regular insulin into a bottle of NPH which could then be unknowingly drawn out later and dropping the patient's BG more than expected since to avoid that we should be drawing cloudy then clear. It's not because the two can't mix because by drawing one then the other we're mixing them in the same syringe. It's not that they can each contaminate each other since that would mean neither clear then cloudy nor cloudy then clear would be acceptable.

I've asked pharmacists about this, one had never heard of such a rule, another claimed it was just a "silly nurse thing", her best guess was that maybe there is some sort of odd long-term incompatibility that only affects a large amount of NPH when contaminated by a small amount of regular, and not vice versa. That's about the only rationale explanation/guess I've ever heard for the rule.

[heron, ASN, RN]

@MunoRN: ya gotta know that I think you're the bee's knees, but my previous post really was the rationale back when I was a wannabe batling (aka student).

Of course, this was almost half a century ago. No such thing as a CBG. Sliding scales, if they were used at all, were a crapshoot based on urine S&As. "Loose control" was the standard and 120 was a normal blood sugar.

In that context, it made sense to be overly cautious with anything that might make insulin's activity less predictable.

Nowadays, it's a different story and the OPs question is a good one. The ritual probably needs to go the way of sippy diets, iced saline lavage and posey vests tied in back: interesting historical footnotes but not clinically relevant.

[Une Infirmiere, BSN, RN]

I don't mix them either. I give them separately. I was taught the clear before cloudy thing in nursing school, but I think it's better to just give them separately. Two small injections is not that bad.

Hmmm IMO most patient rather have one injection...That's why we are though how to mix.

[MunoRN, RN]

@MunoRN: ya gotta know that I think you're the bee's knees, but my previous post really was the rationale back when I was a wannabe batling (aka student).

Of course, this was almost half a century ago. No such thing as a CBG. Sliding scales, if they were used at all, were a crapshoot based on urine S&As. "Loose control" was the standard and 120 was a normal blood sugar.

In that context, it made sense to be overly cautious with anything that might make insulin's activity less predictable.

Nowadays, it's a different story and the OPs question is a good one. The ritual probably needs to go the way of sippy diets, iced saline lavage and posey vests tied in back: interesting historical footnotes but not clinically relevant.

If only adding some NPH to a vial of regular can make it less predictable then that would make sense. But if the reason it makes it less predictable is that getting insulin of one rate of action into a vial of insulin with another rate of action then it makes no sense to have a rule for doing one before the other, whichever order it's done in you could be getting one type of insulin into the vial of another type.

(And of course you're also the bee's knees)

[heron, ASN, RN]

@Muno - the thinking was that it was riskier to have the shorter-acting insulin extended unpredictably by contamination. Hence the rule. Not that I've ever heard or read of a dangerous drop in blood sugar due to repeated dosing from a contaminated multiple-dose vial ... But that was the line of reasoning at the time.

Makes no sense at all now. 40-odd years of data on pathophysiology of DM, insulin metabolism and monitoring technology make a huge difference.

As I said, an interesting historical footnote. Both medicine and nursing are full of useless rules that made theoretical sense at the time.

[Cell-Nurse]

sorry if my question stirred the pot a little. I should of maybe given some background that I nurse in a prison (hints the cell portion of my name). which...Is about 1 step up from nursing in a 3rd world country. Were not exactly privileged in terms of fancy unnecessary equipment like....IV pumps XD

So, pretty much all insulin that is mixed is drawn in 1 syringe(was accused of being wasteful for using 2) Were correct on lantus but in my defense I only had 1 patient out of 100+ that took it & he got shipped to another unit.

Thank you all for the info. Will defiantly be reading up. Didn't think about google scholar, used google but to no avail. Mahalo.

[NuGuyNurse2b]

Hmmm IMO most patient rather have one injection...That's why we are though how to mix.

same here. when I read that I went HUH? putting the patient at risk for lipodystrophy, no?

[tinad207]

It's all about contamination . If you were to draw NPH first( cloudy) , the residue of drawing it up would contaminate the clear ( fast acting ) vial. NPH has the component of protamine in it, hence the name ( Neutral Protamine Hagedorn). You don't want to contaminate the clear insulin vial with the protamine component of NPH because it would counteract the expected effectiveness of the clear insulin ( "peak" levels etc). I also believe this is an outdated practice . Wondering if there have been recent studies regarding the effectivess of this technique that seems to have disappeared all together .