For some reason, those in the US choose to list the slower, NPH/isophane based insulin fraction first, such as Humulin or Novolin 70/30. The rest of the world gives the faster insulin top billing and the result is 30/70 . Regardless of how this is written, it means that the insulin is made up of 70% NPH/isophane insulin and 30% R/neutral insulin.
The most common mixes are 70/30 (30/70) (non analog) or 75/25 (25/75) (analog). There are no currently-marketed mixes which combine insulins of different origins. Eli Lilly's form of beef/pork Iletin and Novo Nordisk's Lentard were discontinued some time ago.
For the most part, non-mixed Intermediate-acting insulins are generally used for dogs with diabetes. Here are the most common ones that could cause confusion:
|Non-Analog Mixed Insulins|
|Insulin Is||Expressed As||Expressed As|
|10% R/Neutral Insulin|
90% NPH/Isophane Insulin
|20% R/Neutral Insulin|
80% NPH/Isophane Insulin
|30% R/Neutral Insulin|
80% NPH/Isophane Insulin
|40% R/Neutral Insulin|
60% NPH/Isophane Insulin
|50% R/Neutral Insulin|
50% NPH/Isophane Insulin
Specifications of mixed insulinsEdit
British National Formulary  classes all of them as biphasic  insulins--having more than one activity or action. Regardless of their origin, the two actions are that of the fast/rapid or short acting insulin in combination with the intermediate-acting isophane or isophane-suspended analog insulin. The activity profiles of the mixed or biphasic insulins vary by whether they are analog or non-analog insulins and the fractions of the faster and slower insulins used in the mix.
There are other various mixes (all human origin) on the market in other countries; the R/neutral fraction or percentage ranges from 10 to 50. In the US, only 70/30 remains on the market, with a wider range available in other parts of the world.
Why Lente doesn't equal 70/30Edit
Let's look at the differences in the two insulins. Lente is comprised of 70 % long-acting Ultralente insulin and 30% short-acting Semilente insulin. So proportions of a long-acting and short-acting insulin are being combined to produce a intermediate-acting insulin. Both Ultralente and Semilente insulin are suspended by adding zinc and the size of their respective insulin crystals. The largest insulin crystals are those of Ultralente, while Semilente contains the smallest, or microcrystals. Simply put, you're combining a long insulin and a short insulin to make an intermediate-acting one.
70/30 insulin starts with 70% NPH/isophane insulin, an intermediate-acting insulin which is suspended by protamine. To that, 30% R/neutral/normal insulin, which is short-acting and soluble, meaning there is no suspension; nothing is added to this insulin to delay its action. In this case, you are taking an intermediate-acting insulin with a suspension and adding to it a short-acting one with no suspension to create an intermediate-acting insulin.
So we have an insulin (Lente), made up of a long-acting and short-acting insulin, both with zinc suspensions, and a mixed insulin (70/30), made from an intermediate-acting protamine suspended insulin and a short-acting one without any suspension. Because of these differences, the insulin action profile for these two insulins is going to be quite different, even though both insulins are classed as intermediate-acting.
These are not as widely varied. The "basics" are that they most commonly come in 70/30 (30/70) or 75/25 (25/75) fractions. Made of either insulin aspart (Novo) or insulin lispro (Lilly), they are a combination of the fast/rapid acting analog insulin and the same analog insulin which has been "slowed down" by a process of creating special crystals of either insulin aspart or insulin lispro with protamine suspension.
The same is true for analog mixed insulins as for non-analog ones regarding the US listing the percentage or fraction of the slower insulin first and everyone else choosing to list the faster action portion that way.
Analog mixed insulins
|All intermediate acting|
Humalog Mix 25
Humalog Mix 50
- Diabetes control in Siberian Husky-Vet Info Richards, Mike, VetInfo4Dogs.
Details about using mixed non-analog insulins with canine diabetes patient & discussinguse of mixed insulins.
- Insulins & Mixtures-NHS UK
- NACDS-Insulin Chart-Page 2
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