Dispensing Considerations With U-500 Insulin Therapy


Dhiren Patel, PharmD, and Jasmine D. Gonzalvo, PharmD, suggest important considerations for pharmacists when dispensing U-500 insulin therapy to patients with type 2 diabetes mellitus.

Dhiren Patel, PharmD: U-500 is actually a very unique insulin. By unique, what I mean is that it has properties of basal insulin, but it also has properties of a bolus insulin. And so, U-500 is Humulin R. It’s available in a vial. It’s also available in the KwikPen, which is another difference that exists within the concentrated insulins currently. All of the other concentrated insulins that are available on the market are only available in the pen device. This is one of the only exceptions in which there’s a vial, a syringe, and a KwikPen device.

The FDA did recently approve a dedicated syringe for U-500, which makes it much easier. You don’t have to use a normal TB or an allergy syringe, which was previously done before there was a dedicated syringe for it. To minimize some of the conversions and the prescriber burden, the FDA has mandated that—if you look in the package insert, it specifically recommended—if a patient is getting a prescription for U-500 being dispensed in the vial, it should go with the dedicate syringe that’s made.

At our institution, what we’re doing is switching a lot of our patients over from the vial and the syringe to the KwikPen, which was also recently approved and simplifies it. It brings back the units to the patient, because previously we had U-100 and then U-500. There was nothing that existed between. And so, those patients were always used to doing volume injections. What the pen device allows them to do is now go back to units and titrate in 5-unit increments.

Again, it simplifies it. It gets them back to what they’re used to, especially in your new starts or your patients who you’re converting over to U-500. It’s the same language, the same way that you have been titrating it, so it’s not another learning curve. Some of those points have helped cut down on some of the confusion and the mix-up as to what should happen when you get that prescription for U-500. And so, just because you have 2 different options, it’s important to clarify with the provider as to what you’re looking to do. Is it the dedicated syringe and vial route that the patient’s going down, or is it the KwikPen route? Because each is going to have different counseling points associated with it.

Jasmine D. Gonzalvo, PharmD: The U-500 pen is readily available, and at this point I haven’t had any problems ordering the U-500 pen for any of my patients. Of course, the syringe is also available. The syringe can be used in combination with the vial. For dosing conversions, it’s really easy. For most patients, it’s going to be 1-to-1, and for anybody with an A1C less than 8%, we’re just going to decease their U-100 dose by 20% and that would be the U-500 equivalent dose to switch to. Both have been simple in my practice, switching either to the pen or switching to the syringe and vial. It has been pretty easy, as long as I spend a significant amount of time going over the differences of the insulins with my patients trying to prevent anything bad from happening while switching from a U-100 or a less potent insulin to the more potent U-500 insulin. Potency is in terms of there being a lot of adverse effects that could happen if someone were to misuse or use a dose too high with those insulins. There would be potential for increased consequences from that.

Dhiren Patel, PharmD: When dispensing U-500 from the pharmacist’s standpoint, there are a few things to keep in mind. The reason it’s a little bit unique to U-500 is that most pharmacists typically don’t frequently see prescriptions for U-500 come in at the same pace that another insulin prescription might come in. In addition to that prescribing of it, the properties of it are different, which impacts all the way down to the level of counseling: not just counseling, but also to making sure what prior regimen the patient was on.

Step 1 is calculating how much insulin the patient was being given and making sure that calculation, that conversion, was correct. That’s very important. In most cases, the patients are on a monotherapy of U-500, but there are cases and some areas in which a patient could be on different types of insulin. Make sure that is correct. And if that means picking up a phone call and talking to that provider, it’s worth doing for those prescriptions because it’s really important to make sure that with this patient population they have the best glycemic control and make sure something that should have been on is not on and vice versa. So, that’s number one.

The other steps are regarding the administration of it. With a lot of different insulins, there are dedicated pen devices that exist, which exist here with the U-500 KwikPen. And if that’s what’s being dispensed, then you would need to be dispensing the appropriate pen needles. However, it also is available in a vial. And so, if it is being dispensed and it has been written for a vial and that’s what’s covered, then there’s a dedicated syringe that needs to be used alongside that. Many pharmacies don’t routinely stock it because it’s not something that is normally dispensed quite often. There are pharmacies in which you may be inclined to give patients a TB syringe or an allergy syringe, or even a regular U-100 insulin syringe, and then just make a calculation on your end and explain it to the patient. But it’s actually very important that you stick with the dedicated syringe, because it has been specifically designed for U-500.

And then, the last step is regarding the ongoing management of it. Just because the prescription is right and it came in OK, that doesn’t mean that’s the way the prescription’s going to be for the next 2 or 3 fills. Those variations are going to occur in terms of the adjustments. Again, if you can care coordinate that back with the provider, I think that would be very helpful because it’s one of those insulins that requires a lot of touch points in making sure that you got it right, especially when it overcomes the insulin resistance that is usually initiated with high insulin dose users. If you overcome that barrier quickly, there is an opportunity to counsel that patient on making sure they don’t become hypoglycemic or hyperglycemic if the conversion wasn’t done properly.

When you look at U-500, there’s a variety of different approaches when you’re initiating insulin or even transitioning a patient. There have been some validated studies that they’ve done that are not included in the actual package insert. They have done studies in patients using twice-a-day as well as 3-times-a-day dosing. That’s an area where it could cause some confusion. Both have been validated, both produced those outcomes, but it’s going to differ as to which patient is going to best respond to which regimen. The twice-a-day regimen might be ideal for a patient who might not be able to inject 3 times a day based off of meals or based off of their pattern, their schedules. That’s most of my patients in whom I initiate a twice-a-day regimen. I will switch from a twice-a-day regimen to a 3-times-a-day regimen typically when I get to around 300 units of total daily insulin, which the patients have responded a little bit better to in terms of glycemic control as well as the frequency of injections.

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