[vegasvic]

Whoa, you lost me there too!

A 10ml bottle of insulin U-100 contains 1000 units of insulin. (U-100 = 100units/ml X10ml = 1,000units insulin). Theoretically, if you’re using 10 units (0.1ml) daily it should last you 100 days (1,000 units/10units/day =100 days).

All things being equal if you have a U-100 scale on your syringe and you pull up 100 units regardless of the needle size/length you should have 1ml insulin. Three-tenths (3/10) is the size of the syringe and not the needle so if you pull up to the 30 unit mark you have 0.3ml not 1ml.

The insulin manufacturer suggests that once opened the vial of insulin is only to be used for 28 days at room temp or refrigerated temps or until the expiration date which ever is reached first. All the entering of the vial over a 28 days period makes introducing something that might grow in the insulin more likely so they suggest you toss it after 28 days. After being entered so many times the membrane loses its integrity and that my make it less than sterile also. Its up to you of course. Without looking at studies, you have to realize that after a period of time at RT the activity of the insulin will decrease and this could be another reason why the manufacturer states 28 days, they are covering their and your butts.

If cost is your concern and you are going to use it after 28 days anyway then be sure to check for a darkening of the liquid or clumping of the suspension or cloudiness (all depending which type you are using of course). And store it in the refrigerator when not in use, that should slow down any growth may want to occur.

vic