Dispensing Insulin and Other Injectable Diabetes Meds

Insulin is a hormone secreted by the pancreas. It helps the body use glucose (sugar) as an energy source by acting like a “key” that allows glucose to enter the body’s tissues. People with diabetes either don’t produce insulin (type 1) or don’t use available insulin properly or make enough insulin (type 2). Without the right amounts or proper functioning of insulin, glucose builds up in the blood and other organs and causes tissue damage or death. Although type 2 diabetes can often be managed with oral medications, many type 2 patients and all type 1 patients will require injections of insulin.

There are many types of insulin available to meet patients’ individual needs, such as the traditional versions with 100 units/mL of insulin, called U-100. There are also some “concentrated” versions that have 200 units/mL (Humalog U-200, Tresiba U-200), 300 units/mL (Toujeo SoloStar and Toujeo Max SoloStar [U.S.]), or 500 units/mL (Humulin R 500 units/mL [U.S.], Entuzity Kwikpen [Canada]).

There are also other injectable drugs used to treat diabetes besides insulin. They include exenatide (Byetta), exenatide extended-release (Bydureon, Bydureon BCise [U.S.]), liraglutide (Victoza), lixisenatide (Adlyxin [U.S.], Adlyxine [Canada]), dulaglutide (Trulicity), and semaglutide (Ozempic). These “GLP-1 agonist” meds help increase the body’s own natural secretion of insulin. Pramlintide (Symlin [U.S.]) is another injectable diabetes med. It helps reduce blood glucose in a different way than increasing insulin levels.

Insulins are considered high-risk medications because they are frequently implicated in serious medication errors. With high-risk meds, even small errors can be deadly. Examples of insulin errors include confusion between insulin products, concentrations, or dosage forms, and the use of dangerous abbreviations such as “u” for units on Rxs for insulin. “U” can be mistaken for a number “4” or a zero, resulting in an overdose. Be vigilant when dispensing insulin and other injectable diabetes meds, and refer Rxs that seem inappropriate to your pharmacist. You can learn more about safety considerations with high-risk meds by taking our CE, Improving Safety with High-Alert Medications in the Community.

Humulin R, 4 D, T Vial, NR

Mrs. Mackey, a 55-year-old female patient, presents a prescription for one vial of insulin to be used as directed. You notice that the abbreviation “ud,” meaning “use as directed,” could easily be mistaken for “4 days” or “40.” You also see a letter that could either be an “N” or an “R” after the drug name. This could lead to incorrect interpretation of the prescription as being written for Humulin N instead of Humulin R, or vice versa. There’s also no concentration specified on the order, so it’s unclear if the patient should get Humulin R U-100 or Humulin R U-500. You check with your pharmacist, who is able to clarify with the prescriber that the order is for Humulin R U-100.

What should be done when inputting an insulin or other injectable diabetes med Rx?

Choose the correct product. Some brands of insulin, such as Lantus and Humalog U-100, come in both a vial and as a pen. Pay attention to different formulations of the same med, and be sure to select the right one. Watch out for mix-ups between look-alike/sound-alike drug names too, such as Byetta and Bydureon or Bydureon and Bydureon BCise. Byetta is dosed twice daily. Bydureon and Bydureon BCise are dosed once per week. Although Bydureon and Bydureon BCise both contain extended-release exenatide and are given weekly, they have different devices and can’t be automatically substituted. Humulin and Humalog mix-ups are common. Levemir and Lantus can also be confused. Lantus has even been confused with Humalog even though they look and sound different. Confusion can also arise with diabetes meds that begin with the letter “T,” including Tradjenta (U.S.), Trajenta (Canada), Trulicity, Toujeo SoloStar, Toujeo Max SoloStar (U.S.), and Tresiba. And orders written for “insulin glargine” could be for U-100 Basaglar, Lantus, or Lantus SoloStar or U-300 Toujeo SoloStar or Toujeo Max SoloStar. While orders written for “insulin aspart” could be for Novolog (U.S.), NovoRapid (Canada), or Fiasp. And orders for “insulin lispro” could be for Admelog, Humalog U-100, or Humalog U-200. Don’t automatically switch any of these products, they’re not equivalent.

Double-check that you choose the correct concentration. For example, Tresiba comes in U-100 and U-200 versions. And Humulin R comes in U-100 and U-500 versions. Dispensing the wrong concentration could lead to the patient having dangerously high or dangerously low blood sugar. If you get an Rx without a concentration, clarify this with a pharmacist so the correct product will be dispensed.

Watch for duplicate therapy. Many patients will use more than one type of insulin, such as a shorter-acting insulin (regular, lispro, aspart, etc) with meals and a longer-acting insulin (glargine, detemir, degludec, etc) once a day. However, duplicate therapy issues come into play when the patient has prescriptions for two or more of the same type of insulin. For example, if a patient has prescriptions for both Lantus (insulin glargine) and Levemir (insulin detemir), you should bring this to the attention of the pharmacist. Also, there are some products that are combinations of a GLP-1 agonist and long-acting insulin (e.g., Soliqua [lixisenatide/insulin glargine], Xultophy [liraglutide/insulin degludec]). Be sure that patients taking these meds are no longer getting prescriptions filled for the individual components.

Enter dosing instructions completely. Insulin prescriptions may have especially complex instructions. Be sure to check notes on e-Rxs for extra instructions from the prescriber. Pay special attention when entering dosing instructions for these Rxs into the computer. Make sure the Rx label reads exactly as it is written on the prescription. Additional label space may be required for detailed instructions.

Be aware that a prescriber might write the Rx instructions for insulin as “use as directed,” allowing changes to be communicated directly to the patient. (Insurers frown upon using “use as directed,” and the pharmacist will often need to clarify instructions with the prescriber.) Patients may be instructed by the prescriber on how to vary the dose of their short-acting (e.g., Humulin R) or rapid-acting (e.g., Humalog) insulin depending on what they eat at each meal. You may also see Rxs written for “SS” or “sliding scale” insulin. This is more common in the hospital or nursing home setting. A sliding scale means the dose of insulin varies depending on the patient’s blood sugar.

Enter an accurate quantity to be dispensed. One vial of insulin typically contains 10 mL of insulin. Prescription quantities for liquids are usually entered as the number of mL instead of the number of vials or packages dispensed for reimbursement purposes. In this case, entering the quantity as “1” for the number of insulin vials dispensed may cause inadequate reimbursement. This may be communicated as “1 mL,” instead of the full 10 mL contained in one vial.

For pens that come in multipacks, such as Victoza, make sure to enter the total number of mL in the whole box or carton instead of the number of pens or the number of mL in one pen. For example, a five-pack of insulin pens that contain 3 mL of drug each will require entering a dispense quantity of 15 mL.

Enter an accurate days’ supply. When specific dosing instructions are included, a days’ supply value can be calculated. Divide the total number of units per vial, pen, or box by the total units injected daily.

If a patient uses 100 units of insulin per day, how long will one 10 mL vial of insulin 100 units/mL last?

100 units/mL x 10 mL/vial = 1,000 units/vial; 1,000 units/vial x 1 day/100 units = 10 days

When specific dosing instructions are NOT provided on the prescription, the pharmacist may need to clarify this information with the prescriber’s office. You can also consider asking the patient how they have been advised to take the medication to help you determine how long the medication should last. An incorrect days’ supply entered into the computer can cause future third-party problems. Insurance companies will often reject a claim with a “refill too soon” message if a claim is transmitted before the previous prescription’s days’ supply has passed. For example, if a prescription is entered for a 30-day supply, the insurance will not pay for a refill of that medication if the patient runs out in just 14 days. Also, billing incorrectly can lead to audits or chargebacks.

Get the pharmacist involved if insulin is too expensive. They may be able to get the patient switched to a more affordable insulin product. For example, regular insulin, NPH, or 70/30 insulin may be less expensive than other types of insulin and can lower blood sugar levels similar to other types of insulin. Generic versions of insulin may also help patients save money. For instance, authorized generics for Humalog U-100 (insulin lispro), NovoLog (insulin aspart), and NovoLog Mix 70/30 (insulin aspart protamine/insulin aspart) were recently brought to market in the U.S. These authorized generics are less expensive than the brand and lower blood glucose the same amount as the brand. Also pay attention to late refills for insulin prescriptions; this could be a sign that patients are rationing to save money.

Since Mrs. Mackey’s prescription indicated to “use as directed,” the pharmacist calls the prescriber’s office to get more specific instructions to help prevent an insurance audit. The detailed instructions are to use 15 units of insulin with each meal. You enter the quantity dispensed as 10 mL and calculate that if Mrs. Mackey eats three meals a day, she is expected to use about 45 units each day. You enter a days’ supply of 22 days (1,000 units/vial x 1 day/45 units = 22 days/vial).

What should be done when selecting insulin or other injectable diabetes meds from the fridge?

There are several different types of insulins available. Human insulin analogs are human insulin that has been modified to make the insulin act more quickly for use around mealtimes (e.g., NovoLog [U.S.], NovoRapid [Canada], Humalog, Apidra) or last longer (e.g., Basaglar, Levemir, Lantus). Mixtures of short- and longer-acting insulins are also available to reduce the number of injections for patients requiring both types. For example, Humulin 70/30 is 70% NPH (an intermediate-acting insulin) and 30% regular insulin (a short-acting insulin). It’s a good idea to use separate bins or shelf alerts to distinguish among products that look similar.

As mentioned, insulin most commonly comes in a concentration of 100 units per mL, or U-100. Vials contain 10 mL, or 1,000 units (100 units/mL x 10 mL/vial = 1,000 units/vial). The 500 unit per mL version of Humulin R is available by prescription in the U.S. for patients requiring large doses. In Canada, U-500 insulin (Entuzity Kwikpen) is also available by prescription. If this very concentrated insulin, or other concentrated insulins, such as Toujeo or Tresiba U-200, are available in your pharmacy, consider keeping them in a special place in the fridge to avoid mix-ups.

Many insulins, such as Humalog, Lantus, and NovoLog (U.S.), are available as pre-filled pens, or as cartridges to be used with a reusable pen. The other injectable diabetes meds (e.g., exenatide, liraglutide, pramlintide) also come as pre-filled pens. With pens, patients just “dial up” the dose they need and inject it. For more details about all the insulins and the other injectable meds for diabetes, including formulations, storage, administration devices, cost, etc, see our charts, Comparison of Insulins (U.S. subscribers; Canadian subscribers) and Comparison of GLP-1 Agonists (U.S. subscribers; Canadian subscribers). If you see that a patient is switching from one pen device to another, let the pharmacist know so that he or she can make sure the patient knows the proper technique for using the new pen.

To fill Mrs. Mackey’s Rx, you choose Humulin R, which is regular human insulin. When you remove the insulin from the refrigerator, you take care not to confuse Humulin R with Humulin N (an intermediate-acting insulin), Humalog (a rapid-acting analog), or a Humulin or Humalog mixture. You also make sure you have U-100 and not the higher strength U-500.

What should be considered when labeling insulin or other injectable diabetes meds?

When labeling insulin and other injectable diabetes meds, take care not to cover the name of the product, storage information, expiration date, and NDC code (DIN in Canada) that may be printed on the box. If more than one vial or package of pens is needed to fill a prescription, print duplicate labels.

A label with a “use by” date is helpful for the patient, since these meds are usually good for around a month (often less than this for pens) once they are dispensed and stored at room temperature. For patients who get a supply of multiple vials or pens to last for a few months, a “refrigerate” label is helpful to remind them to keep the med in the fridge until they start using it. Our charts, Comparison of Insulins and Comparison of GLP-1 Agonists, also have information on room temperature stabilities.

It’s important to note that most insulins and other injectable meds that come in pens should not be placed back in the refrigerator once they are in use. At this point, they should usually only be stored at room temperature. Storing them in the fridge can actually cause some pens to malfunction and leak.

In the hospital setting, keep in mind the mantra “one pen, one patient.” It is important to label insulin pens for individual patients. Make sure a patient-specific label is attached to the pen itself and not just to the cap or the bag it is delivered in to help prevent mix-ups between patients. Even if the needle on a pen is changed, there is still a risk for cross contamination between patients. Nurses should never use one patient’s pen to administer insulin to another patient.

Get our chart, Tips to Improve Insulin Safety, for more strategies to help prevent errors with insulin.

Although Humulin R requires refrigeration while stored in the pharmacy, it can be kept at room temperature for up to 28 days once in use. You place an auxiliary label indicating this on Mrs. Mackey’s prescription. When the pharmacist counsels Mrs. Mackey, he also gives her storage information.

What workflow considerations apply to insulin and other injectable diabetes meds?

Once the Rx is ready, it should be stored in the refrigerator until it’s picked up. Workflow for storage and retrieval of refrigerated Rxs such as insulin varies among pharmacies. Many pharmacies place an empty bag, label, and receipt in an alphabetized bin near the cash register, but store medication in a “patient pickup” bin in the refrigerator. With this method, Rx bags are located in the normal pharmacy storage area, while insulin is stored in the fridge. Make sure to use a “refrigerate” sticker or another reminder on the receipt and bag with this method, to ensure that the insulin is retrieved from the refrigerator when the patient pays for the Rx. Other pharmacies may have a separate storage area in the refrigerator for labeled and bagged prescriptions that are ready to be picked up. Get our technician tutorial, Keep It Cool: Storing Meds in the Fridge or Freezer, for more information on proper storage of refrigerated meds.

What should be considered when dispensing insulin syringes and pen needles?

Most insulin syringes and pen needles can be purchased without a prescription however, a prescription is required for third-party coverage. In some locations, depending on state law or store policy, insulin syringes require a prescription, or can only be dispensed along with insulin. Be sure to enter the insulin prescription in the computer before prescriptions for syringes or other diabetes supplies. Some third-party payers reject coverage for diabetes supplies until the insulin prescription has been entered because they need to detect an “active” insulin prescription to justify the diabetes supplies.

Insulin syringes are marked in units, not in mL like most other syringes. Most insulin syringes are designed to be used with insulin vials containing insulin at a concentration of 100 units per mL. Insulin syringes differ in the total amount of insulin they can hold (e.g., 100 units [1 mL], 50 units [0.5 mL], 30 units [0.3 mL]). Insulin syringes come with a needle attached. The “gauge” of the needle tells you how fine, or thin, the needle is. The larger the gauge, the thinner the needle. For example, 31-gauge needles are thinner than 28-gauge needles. Thinner needles may be more comfortable for the patient, they also get bent more easily. Needles also differ in regard to the length. Some common needle lengths are ½ inch (12.7 mm) and 5/16 inch (8 mm). Some patients prefer shorter needles for comfort. But shorter needles may not be long enough for overweight patients. Refer patients who complain about injection pain to the pharmacist. They may need a shorter and/or thinner needle.

Keep in mind that an insulin syringe specifically for use with U-500 insulin is now available in the U.S. These syringes will help patients who use Humulin R U-500 vials avoid dangerous dosing errors that can happen when they draw their doses up with syringes meant to measure out U-100 insulin. These U-500 syringes require a prescription, and should only be used with U-500 insulin. It’s important not to mix them up with U-100 syringes. The U-500 syringes come in a green box, with a green cap and “U-500” on the barrel, to match up with newer U-500 insulin labeling and to help prevent errors.

Unlike insulin syringes, insulin pens and other injectable diabetes meds require pen needles. When dispensing an insulin pen, be sure to choose the correct pen needle for the specific pen. Pen needles come in different sizes, similar to needles on insulin syringes. If you are unsure of which brand name or needle type a patient’s pen requires, check with the pharmacist. You may also be able to find this info in the “How Supplied” section of the prescribing information in the U.S., or the “Dosage Forms, Composition and Packaging” section of the product monograph in Canada. Process the pens and pen needles as two separate prescriptions. Even though pen needles are OTC, most insurances will cover them as long as the patient has a prescription for them. Patients should be discouraged from reusing their pen needles or leaving them on their pen. Reuse can increase the risk of injection pain and infection. Leaving them on can cause air bubbles, leaks, contamination, or clogging of the pen. Watch for patients who switch pen needle brands. The way pen needles are used may differ between products.

Lantus, 15 u HS, 1 month's supply, Rx3

Mrs. Mackey returns the next day with the following prescription, which she forgot to bring in before: Lantus 15 units at bedtime, dispense a one-month supply, with three refills. Lantus is insulin glargine, a long-acting insulin. You know that it’s normal for a patient to use more than one type of insulin at a time.

How do you calculate how much insulin to dispense? How is this entered into the computer?

Mrs. Mackey will need 15 units per day for 30 days. You calculate that she will need 450 units for a 30-day supply (15 units/day x 30 days = 450 units). You know that each 10 mL insulin vial contains 1,000 units of insulin (100 units/mL x 10 mL/vial = 1,000 units/vial), so you dispense one vial of Lantus for a one-month supply. However, since Lantus vials must be discarded after 28 days once they are in use, you enter a 28-day supply into the computer.

Keep insulin storage and stability in mind when entering days’ supply for insulin Rxs. In the above example, Mrs. Mackey will only use about one-half of one Lantus vial in 30 days at her current dose of 15 units daily. When entering the days’ supply amount for this Rx, it would seem logical that one vial is enough insulin for two months. However, any in-use Lantus vials should be discarded after 28 days. As such, this Rx should be entered into the computer as being for one 10 mL vial and a 28-day supply.

Also be alert for patients requiring multiple vials for a one-month supply of insulin. For example, if this Rx had been for 40 units at bedtime, two vials (20 mL) would be dispensed (40 units/day x 30 days = 1,200 units, requiring two vials). Also consider the patient’s third-party coverage. In some cases, the patient pays less if they get a 90-day supply at one time. If Mrs. Mackey’s Rx was written for a 90-day supply, that would be three vials of Lantus, taking the 28-day expiration for an “in use” vial into account. The pharmacist would tell Mrs. Mackey to keep the unused vials in the refrigerator until she needs them.

Dispensing pens can be tricky. It’s important to be aware that in the U.S., the FDA-approved labeling for insulin pens now explicitly states to dispense in the original sealed carton. This helps ensure patients get the “Patient Information” and “Instructions for Use” which come with each box. In the past, pharmacies may have broken a box in order to dispense just enough insulin to meet payer quantity limits. With this recent change to the FDA-approved labeling, now pharmacies are at risk of audit if they DON’T dispense a full box. This can pose a challenge depending on how much insulin a patient is using. For example, if the Rx above was for Lantus SoloStar, authorization from Mrs. Mackey’s prescriber will be needed to change the Rx quantity to a full box of the Lantus SoloStar pens. The full box would be entered into the computer with a quantity of 15 mL (5 pens x 3 mL), and a days’ supply of 100 days (300 units/pen x 1 day/15 units = 20 days/pen; 5 pens x 20 days/pen = 100 days). Many insurance companies have days’ supply limits, and in this example, 100 days will likely exceed most insurance company limits. Always follow your company’s policy on how to handle these situations, and consider some general best practices. For example, dispense a full box and always first bill an accurate days’ supply based on the prescribed quantity. If plan limits are exceeded, call the payer’s help desk to request an override. If no override is available, clearly document the payer’s guidance on the Rx hard copy and in the computer. For example, you’ll want to make note of insurance limits, actual days’ supply, and whether to adjust days’ supply. Talk to your pharmacist about including the actual days’ supply in the Rx sig, such as, “1 box should last 100 days.” Put a flag in the patient profile to indicate that this Rx shouldn’t be refilled earlier than the date which reflects the actual days’ supply. Be sure not to enroll these Rxs in automatic refill programs, as this could be considered fraud due to overbilling.

Can insulin be dispensed without a prescription?

In the U.S., some insulins are OTC (e.g., Humulin R U-100, etc), while other insulins, such as Lantus, require an Rx. For third-party coverage, an Rx is necessary, even for OTC insulins. In Canada, injectable insulins are nonprescription/Schedule II (i.e., only available with pharmacist assistance).

Project Leader in preparation of this technician tutorial (350780): Flora Harp, PharmD/Associate Editor, last modified March 2020.

Cite this document as follows: Technician Tutorial, Dispensing Insulin and Other Injectable Diabetes Meds. Pharmacist’s Letter/Pharmacy Technician’s Letter. July 2019.

—Continue for a dispensing insulin “cheat sheet”—

“Cheat Sheet” for Dispensing Insulin and Other Injectable Diabetes Meds

What are the different injectable diabetes meds that are available and how do they work?

The common types of injectable diabetes meds include various insulin products (Lantus, Humalog, Novolin, etc) and GLP-1 agonists (exenatide [Byetta], exenatide extended-release [Bydureon, Bydureon BCise (U.S.)], liraglutide [Victoza], lixisenatide [Adlyxin (U.S.), Adlyxine (Canada)], dulaglutide [Trulicity], and semaglutide [Ozempic]). People with diabetes either don’t produce insulin (type 1) or don’t use available insulin properly (type 2). Insulin is needed to help the body use glucose as an energy source and to prevent glucose buildup in the blood and organs. GLP-1 agonists help increase the body’s own natural secretion of insulin.

What should I be sure to do when dispensing insulin or other diabetes meds?

  • Be alert for dangerous abbreviations on insulin Rxs; such as the use of “U” for units, which can be mistaken for the number “4” or a zero, resulting in an overdose.
  • Ask patients if they have ever used the medication before, and get the pharmacist involved to counsel if they haven’t, since administration of an injection can be tricky.
  • Choose the correct product when entering prescriptions and pulling meds from the fridge; there are many different kinds of insulins available with similar names.
  • Make sure to select the correct insulin concentration, since insulin can come in U-100, U-200,
    U-300, and U-500 versions.
  • Watch for duplicate therapy messages and ask the pharmacist to review them.
  • Enter dosing instructions completely, and alert the pharmacist if instructions say to “use as directed;” this often needs to be clarified.
  • Enter accurate quantities and days’ supplies.
    • Quantities are typically calculated in mL for insulin, rather than the number of vials or packages.
    • When calculating days’ supply, divide the total number of units per vial, pen, or box by the total number of units the patient will inject daily.
  • Get the pharmacist involved if patients cannot afford their medications or if you notice late refills.
  • Don’t cover important information when labeling packages (e.g., don’t cover the name of the product, storage info, expiration dates, or NDC/DIN codes).
  • Print duplicate labels if dispensing more than one vial or package of pens.
  • Apply a “use by” auxiliary label so patients know how long their medication is good for while in use.
  • Apply a “refrigerate” auxiliary label if patients are getting multiple packages, to remind them to keep the med in the fridge until they start using it.
  • Follow your pharmacy’s process for keeping the medication stored in the fridge while waiting to be picked up by the patient.

What should be considered when dispensing insulin syringes and pen needles?

  • Enter prescriptions for the injectable med first, since some insurance companies won’t cover syringes or pen needles until they see an “active” prescription for a med requiring these supplies.
  • Be sure you are dispensing the correct needle gauge and length and be aware that in the U.S., there are specific U-500 insulin syringes that must only be used with U-500 insulin.
  • Help discourage patients from reusing pen needles or leaving them on their pen.
  • Watch for patients who switch pen needle brands and get the pharmacist involved since different brands of pen needles may work slightly differently.

[July 2019; 350780]

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