Clear before Cloudy

[Pharmacy Kid]

What's the reason for drawing regular before NPH?

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[BeLikeBueller]

I don't know, but when I utilized the most reliable of all search methods (google 😉), I came across a diabetes help forum where someone had the username "Cinnabon."

If I had to guess though (after a little bit of digging), I would say it is because if you introduce the protamine component from the NPH into the regular insulin vial, you have effectively transformed a small portion of your fast-acting insulin to intermediate acting insulin (since it's an association of insulin with the protamine that causes the increased duration - if I recall insulin pharmacology correctly)? Whereas if you introduce regular insulin into a solution of NPH, regular insulin associating w/ protamine would have really no effect (it's already an intermediate acting insulin after all).

Hopefully someone w/ a greater knowledge base in pharmacology will respond. I just had to share about "Cinnabon" and felt like it was important to add something meaningful to the discussion as well.

 

[zelman]

Nph is also cloudy, and cloudiness in regular insulin would mean it should be discarded.

 

[sakigt]

I was taught it was a contamination issue as well.

 

[Ackj]

If I had to guess though (after a little bit of digging), I would say it is because if you introduce the protamine component from the NPH into the regular insulin vial, you have effectively transformed a small portion of your fast-acting insulin to intermediate acting insulin (since it's an association of insulin with the protamine that causes the increased duration - if I recall insulin pharmacology correctly)? Whereas if you introduce regular insulin into a solution of NPH, regular insulin associating w/ protamine would have really no effect (it's already an intermediate acting insulin after all).

This is more or less what I was taught, although not necessarily due to protamine (you would use the rapid before Lantus, too). I believe it's mainly the fact that you're putting something with a longer duration into a vial that's supposed to be short acting, so you could get a peak at the wrong time and end up bottoming out.

Also with the cloudy NPH, if you get some of that into your rapid, it would probably make the whole vial cloudy, so that's obviously not desirable.

 

[zelman]

This is more or less what I was taught, although not necessarily due to protamine (you would use the rapid before Lantus, too). I believe it's mainly the fact that you're putting something with a longer duration into a vial that's supposed to be short acting, so you could get a peak at the wrong time and end up bottoming out.

Also with the cloudy NPH, if you get some of that into your rapid, it would probably make the whole vial cloudy, so that's obviously not desirable.

I don't think you're supposed to mix lantus.