Review of Medication Error Sources Associated With Inpatient Subcutaneous Insulin: Recommendations for Safe and Cost-Effective Dispensing Practices

Abstract

Background: The challenge of addressing variation in practice is underlined by variation in institutional operational and financial limitations, which ultimately directs institutional insulin dispensing strategy. Insulin therapy is multi-modal, and inpatient pharmacies may be responsible for simultaneously managing up to 8 formulations. While available as a tool for glycemic management in the inpatient setting, intravenous (IV) insulin and insulin pumps are out of scope for this review. Considerations when designing subcutaneous insulin dispensing processes include medication safety, infection control, pharmacy workflow, nursing workflow, drug cost, hardware cost, and hospital policy. Objective: This review provides an overview of common inpatient subcutaneous insulin dispensing practices, describes the regulations directing current practice, and discusses the benefits and risks of each dispensing practice. Finally, the review provides recommendations for subcutaneous insulin dispensing practices with respect to institutional limitations that minimize patient safety risk and consider the variable costs that practices incur. Methods: Common formulations will be presented along with medication safety considerations and potential medication administration errors to preface strategies for management. Conclusion: Nearing the centennial anniversary of the invention of insulin, the practice of dispensing subcutaneous insulin products has remained a core responsibility of the hospital pharmacy as a primary treatment option for Diabetes Mellitus. Despite the continued presence of this product as a universal component of the hospital formulary, subcutaneous insulin dispensing practices remain varied institution-to-institution.

Introduction

Based on the American Diabetes Association (ADA) ¹ Standards of Medical Care in Diabetes, insulin therapy remains the primary method of glycemic management in the inpatient setting. A combination of basal (ie, long acting) and bolus (ie, short acting) insulin should be used to manage hospitalized patients with hyperglycemia. In the United States in 2020, data from the National Diabetes Statistics Report estimated that 34.2 million Americans (10.5% of total Americans) had diabetes, with a total of 7.8 million admissions possessing a diagnosis of diabetes (21.8% of total hospital admissions) in 2016. ² Given these 2 factors, insulin is likely one of the most commonly dispensed products in the hospital setting. Strategies that outline the safest and most efficient pharmacy dispensing processes for these agents remain undefined.

In 2017, the Institute for Safe Medication Practices (ISMP) released guidance for optimization of safe subcutaneous insulin use in adults for safer handling practices within the medication use process. ³ Insulin has been associated with 11% to 16% of harmful medication errors and is considered a high-alert medication.^4-6 In 2019, a National Diabetes Inpatient Audit by the National Health Service within 950-bed, teaching hospital found that 20.2% of inpatient drug charts contained 1 or more insulin errors. ⁴ ISMP defines a high-alert medication as a drug that bears a heightened risk of causing significant patient harm when they are used in error. ³ Efforts to standardize and mitigate the risk of patient harm that insulin causes have been a longstanding focus of inpatient pharmacies. ISMP event analysis has identified that the patient safety risk with dispensing subcutaneous insulin increases when intermediate and long acting insulin doses are not dispensed in the most ready-to-use format. ³ There is an expanding volume of error reports associated with selecting the wrong vial of insulin from unit stock and measuring the wrong dose for administration on the patient care unit.^3-6 Periodic evaluation of dispensing practices and incorporation of best practices is the best solution to risk minimization.

The Centers for Disease Control and Prevention (CDC) offers guidance on utilizing multi-dose vials (MDVs) to minimize the risk of disease transmission. The CDC defines an MDV as a vial of liquid medication intended for parenteral administration that contains more than 1 dose of medication. ⁷ While MDVs contain preservatives to help prevent the growth of bacteria, preservatives do not protect against contamination when healthcare personnel fail to follow safe injection practices. Several insulin formulations may be obtained as MDVs, which presents considerations to reduce the risk of vial contamination. The CDC recommends that MDVs be dedicated to a single patient when possible or kept in a singular medication preparation area separated from the direct patient care area. ⁷ If the MDV enters a patient room, it should be dedicated to single patient use only. Upon vial access, the insulin vial should be discarded according to a beyond-use date (BUD) of either 28 or 42 days as instructed by the manufacturer package insert or upon product expiration, aligning with recommendations provided by The United States Pharmacopeia (USP).

The Joint Commission provides additional guidance to pharmacies on dispensing subcutaneous insulin within the Medication Management Standards for Hospitals found in “Section MM.05.01.11: The hospital safely dispenses medications.” According to The Joint Commission, quantities of medications should be dispensed consistent with patient need. ⁸ The implications of this standard are relevant to the dispensing process when considering the intent to minimize the quantity of unnecessary insulin doses for sliding scale parameters.

The purpose of this review is to provide an overview of common inpatient subcutaneous insulin dispensing practices, describe regulations directing current practice, and discuss the benefits and risks of each dispensing practice. Finally, the review will provide recommendations for insulin dispensing practices with respect to institutional limitations that minimize patient safety risk and consider the variable costs that practices incur.

Background

Short Acting Insulin

Short acting insulins possess a relatively short onset of action and work over a narrow range of time (3-8 hours) to provide correctional or meal-time coverage that may result in a requirement for multiple administrations throughout the day.^9-11 Given the similar roles in therapy, rapid acting insulins will be referred to as short acting insulin for the purpose of this review. Common formulations include insulin aspart (Novolog^®), insulin lispro (Humalog^®), insulin glulisine (Apidra^®), and insulin regular (Humulin R^® or Novolin R^®). Despite ADA guideline recommendation against use, short acting insulin in the form of a sliding scale order is routinely used as first-line therapy in patients on oral agents prior to admission. The operational challenge of managing short acting insulin is that dosing may be scheduled or held based on order parameters; thus, batch filling pharmacy-drawn insulin doses may lead to incremental waste either through lack of utilization or delays in administration which situationally incentivizes the allocation of floor stock. Errors with short acting insulin are usually easily identified and corrected. However, hypoglycemic events may still occur, causing patient harm.

Intermediate Acting Insulin

Intermediate acting insulin contains buffers that extend the onset and duration of action to confer an additional basal rate of insulin release for when blood glucose remains relatively stable. ¹² The only formulation available is insulin NPH (Humulin N^® or Novolin N^®). As a twice-daily agent, this agent is more readily titratable than other basal agents for patients with external causes of hyperglycemia, such as enteral nutrition or glucocorticoid administration. Given the longer duration of action (8-12 hours), insulin NPH is routinely scheduled. Scheduled medications may be more routinely prepared by pharmacy for ready-to-use format in patient-specific doses. Errors with intermediate acting insulin may be more challenging to identify due to the pharmacokinetics of the medication.

Long Acting Insulin

Long acting and ultra long acting insulins possess the most prolonged onset and duration of actions (24-48 hours) relative to other formulations due to the design of a pH-dependent release mechanism providing the longest basal rate of insulin release. ¹³ Long acting formulations include insulin glargine (Lantus^® or Basaglar^®), insulin glargine-yfgn (Semglee^®), insulin detemir (Levemir^®), insulin degludec (Tresiba^®), and concentrated insulin glargine (Toujeo^®). Dosed once or twice daily, this agent is useful for lowering persistent hyperglycemia. Similar to insulin NPH, long acting insulins may be readily prepared by pharmacy for ready-to-use format in patient-specific doses. Errors with long acting insulin may be more challenging to identify due to the pharmacokinetics of the medication. Errors can lead to delayed hypoglycemia and harm if not identified and treated appropriately.

Concentrated Insulin

In patients with severe insulin resistance (ie, requiring more than 200 units of insulin per day to maintain normoglycemia), concentrated insulins are typically employed for type II diabetic management. ⁹ While onset is similar to short acting insulin, duration of action for concentrated insulins is largely dose-dependent, with larger doses generally providing basal coverage. The only formulation commonly available is insulin regular U-500 (Humulin R U-500). Concentrated formulations other than U-500 are unlikely to be on formulary in the inpatient setting and are out of the scope of the recommendations provided below. If concentrated pens are used, typically, they are utilized as patient home medications. Concentrated insulins are high-alert medications and should be managed accordingly as case reports of overdose have been reported in the literature. ¹⁴ Given the infrequency of prescribing, dispensing either patient-specific pens or pharmacy-drawn, patient-specific doses are preferred to minimize the risk of preparation errors (eg, 1 unit on the U-100 insulin syringe is equivalent to 5 units of U-500 insulin) or administration error. Stock concentrated insulin should not be stored on patient care units, and each dose should be prepared or verified by pharmacy given literature suggesting a higher incidence of hypoglycemic events. ¹⁵ In the absence of patient-specific pens, the pharmacy should dispense U-500 doses from vial stock in a patient-specific U-500 syringe. Errors with concentrated insulin can be devastating since the insulin is 5 times more concentrated than typical insulins. Due to the pharmacokinetics, monitoring and treatment of an error may extend over 12 hours.

Insulin Pens

Insulin pens of various formulations are utilized in the inpatient setting to reduce pharmacy and nursing time to prepare and administer insulin. All formulations of short acting, intermediate acting, long acting, and concentrated insulins are available in pen dosage form. While assumed, there is evidence to support that insulin vials and pens confer the same clinical efficacy in achieving glycemic control in the inpatient setting. ¹⁶ The advantages and disadvantages of insulin pens will be discussed further below. Errors with insulin pens are less common due to the human factored design of the pen. However, reports with wrong patient errors have occurred and require blood-borne pathogen monitoring to confirm no harm to the patient. ¹⁷

Medication Administration Errors

Wrong Dose

Wrong dose errors may be defined as the intended patient receiving an intended dose of insulin at an amount differing from the written order, including errors of omission. ¹⁸ Given the varying number of health professionals involved in preparing patient-specific subcutaneous insulin doses, dosing errors may occur when staff are not familiar with standard concentrations or routine doses. For example, a U-100 vial may be mistaken to only contain 100 units of insulin, or a 10 mL vial may be mistaken to contain only 10 units of insulin. There have been numerous reports of adverse drug events associated with wrong dose errors from U-500 concentrated insulin. ³ Additional clinical interpretation of sliding scale orders may lead to doses deviating from the original treatment plan. In any case, lack of product or software familiarity may be contributory to knowledge-based errors. Further dosing errors may be introduced with memory-based errors from incorrectly drawn doses, interruptions, or communication between staff.

Wrong Patient

Wrong patient errors occur as an unordered drug error for the patient receiving the subcutaneous insulin dose and an error of omission for the intended patient. ¹⁸ While barcode medication administration (BCMA) is a commonplace feature in many hospitals, inadequate compliance or lack of patient-specific labeling may lead to unintended administration. Wrong patient errors may also occur in the prescribing and transcribing process when orders are incorrectly input for the wrong patient yet are correctly dispensed and administered.

Wrong Drug

Wrong drug errors represent the administration of an incorrect insulin product. Wrong drug errors may be introduced in the prescribing, transcribing, dispensing, or administration processes. ¹⁸ Attention to selecting the correct insulin product when ordering or preparing insulin doses should be taken to minimize the risk of administering the wrong product. Access to a variety of floor stock insulin products may amplify the risk of wrong drug errors in the setting of subcutaneous insulin administration.

Monitoring Error

While inappropriate monitoring may lead to uncontrolled blood glucose levels resulting in increased morbidity, monitoring errors may also lead to improper management of insulin administration. The American Diabetes Association recommends that blood glucose be monitored in accordance with meal schedule. While alterations in dietary status, renal function, acuity, or introduction of drug interactions should ensure that blood glucose is monitored 4-to-6 times daily. ¹ Error in monitoring may lead to suboptimal therapy or overtreatment as exogenous insulin requirements fluctuate.

Wrong Time

Wrong time errors are doses that are administered greater than 60 minutes from the intended administration time. Not including instances of documentation omission, wrong time errors occur in the transcribing, dispensing, administration, and monitoring process from pharmacy delay, with the presence of more acute patient needs, or with patient-related factors (eg, the patient is sleeping, is in a procedure, patient transfer, or has not yet eaten). ¹⁸ Orders may also be incorrectly timed, leading to wrong time errors.

Wrong Route

Since insulin may be given intravenously or subcutaneously, there is additional potential for wrong route errors in the prescribing, transcribing, or administration processes. ¹⁹ A correctional insulin order may be incorrectly input for an intravenous route when subcutaneous administration is intended. Comparatively, the medication may be incorrectly administered when ordered correctly. Either method of error may confer suboptimal treatment or overdose requiring correctional administration of additional insulin or closer monitoring for hypoglycemia.

Insulin Dispensing Practices

Variation in inpatient subcutaneous insulin dispensing practice may be delineated into 2 categories: product selection and workflow design. Product selection variation originates from institutional clinical practice and formulary determination. Product pricing and provider prescribing preference will primarily dictate bolus and basal insulin therapy choice to treat hyperglycemia. The impact of product selection may result in the utilization of vials versus pens. However, the majority of variation in practice will be driven by the institution’s workflow design between sterile compounding, automated dispensing cabinet (ADC) restocking, and nurse medication administration. The design of the dispensing process is done with resource availability (eg, labor, hardware, software, and supplies) in mind. The following list defines the key variabilities that must be considered when outlining any subcutaneous insulin dispensing practices:

1. Source of product: vial or pen

2. Product that is dispensed: vial, pen, or pharmacy-prepared syringe

3. Location of product dispensed: pharmacy or ADC

4. Personnel labeling the product: pharmacy or nurse

5. Recipient(s) of the dispensed product: multiple patients or a single patient.

Pharmacy Dispensing

As previously mentioned, the utilization of vials or pens is a differentiating factor across institutions. Product may be dispensed as patient-specific in the original container with multiple doses intended for a single patient or as a patient-specific, drawn-up syringe intended for a single patient. Patient-specific syringes containing long acting or intermediate acting insulin and patient-specific insulin pens dispensed by a central pharmacy are used to reduce the risk of inaccurate dosing, provide a ready-to-use format, decrease pharmacy and nursing time in preparation, decrease needle-stick injuries, and prevent cross-contamination.^19-22 Cross-contamination may occur through direct or indirect contact with potentially contaminated surfaces or equipment such as when a multi-dose vial is re-entered with a contaminated needle or when an insulin pen is used for multiple patients. For concentrated insulins, the use of pens may confer an additional safety benefit by removing U-500 syringes from circulation with proper inventory management processes in place to prevent mix-up with other potential insulin pen products. However, patient-specific pens are more expensive than stocking vials, are prone to duplicate dispensing, have the potential for premature needle withdrawal leading to underdosing, and must be primed prior to first administration, leading to waste.^23-27 In a survey of 474 inpatient institutions, 30% (142) reported inadvertently using insulin pens on multiple patients despite CDC recommendation that insulin pens be patient-specific.^28,29 Comparatively, single-use, patient-specific syringes are prepared in a sterile environment and verified in the pharmacy to ensure product and dose accuracy.

Floor Stock

MDVs stocked in an ADC throughout the hospital are utilized to minimize waste at the expense of additional work to ensure patient safety. Floor stock vials or pens may be labeled and assigned as patient-specific with multiple doses for a single patient or remain as non-patient-specific ADC stock inventoried per unit with multiple doses for multiple patients. As MDVs stored in ADCs are prone to human error, operational processes outlining the proper identification of the vial and patient must be well-designed with proper procedure to ensure sterile administration and minimize cross-contamination. A 2-nurse double-check is only recommended for insulin intended for intravenous administration and is no longer recommended for subcutaneous insulin. ³⁰ Subcutaneous Insulin doses prepared by a nurse may be verified in several ways:

1. The prepared dose is labeled with a patient-specific label that has a barcode generated by the ADC printer.

2. The prepared dose is labeled with a generic barcode label stocked in or around the ADC.

3. The patient-specific vial is scanned at the patient bedside.

4. The floor stock vial is scanned in the medication room with a mobile scanner. The mobile scanner is then used to scan the patient prior to administration.

5. The product is not scanned or labeled.

When examining workflow for utilization of MDVs for nurse-drawn preparation, the hospital pharmacy is typically responsible for monitoring expiration dating, removing expired vials, and restocking to a unit-specific inventory count. Insulin MDVs have an expiration date of either 28 days, 42 days, or as instructed by the manufacturer package insert once the protective seal has been punctured or upon storage at room temperature. ⁸ Expiration reporting functionality may be automated through the ADC. However, some institutions store MDVs in ADC refrigerators with the expectation for manual documentation of expiration dating by nursing or pharmacy when puncturing the vial. With nursing documentation, there is a reduced waste by ensuring the product is short-dated upon initial use. Alternatively, pharmacy may manually pre-date the vials stored in the ADC refrigerator and re-label if the refrigerated product remains unused. Both manual processes are prone to error of omission.

Cost

A review of available insulin formulations with associated costs is listed below (Table 1). Costs are organized by Average Wholesale Price (AWP) pricing for 3 mL vials, 3 mL pens, and 10 mL vials for comparison.

Table 1.

Cost Comparison of Available Insulin Products. ³¹

Insulin Product	3 mL Vial	3 mL Pen	10 mL Vial
Regular 100 units/mL	$49.56	$62.46	$165.20
Lispro 100 units/mL	$98.88	$127.29	$329.60
Aspart 100 units/mL	$104.16	$134.13	$347.20
Glulisine 100 units/mL	$102.21	$131.64	$340.70
NPH 100 units/mL	$49.56	$62.46	$165.20
Glargine 100 units/mL	–	$102.06	$340.30
Glargine-yfgn 100 units/mL	–	$35.52	$118.40
Detemir 100 units/mL	–	$110.94	$369.80
Degludec 100 units/mL	–	$122.01	$406.70
U-500 500 units/mL	$267.66	$344.52	$1784.40 a

mL = milliliter.

^aProduct available as a 20 mL vial.

In 2019, the average length of stay (ALOS) for hospitalized patients in the United States was 5.5 days. ³² For an illustration of cost difference, total short acting insulin cost across ALOS for floor stock vials, patient-specific vials, and patient-specific pens will be extrapolated for insulin regular at a dose of 12 units daily using each formulation. Utilizing floor stock 10 mL vials or 3 mL vials results in a total AWP acquisition cost of $10.90, while a patient-specific 3 mL vial would result in a total AWP acquisition cost of $49.56, assuming vial wasting following discharge. Comparatively, short acting, patient-specific pen usage would result in a total AWP cost of $62.46, assuming pen wasting following discharge. While AWP pricing does not reflect pharmacy acquisition costs in practice, the relationship in pricing between products holds true for contractual pricing through Wholesale Acquisition Cost or Group Purchasing Organizations. Additionally, the demonstrative analysis performed aligns with the literature. In prior budget impact analyses, utilizing short acting 3 mL floor stock vials has considerably reduced acquisition cost and waste.^27,33 When considering cost for short acting insulin products, preference should be shown for 3 mL vial products with larger volume vials and pens reserved for pharmacy dispensed products (ie, intermediate acting, long acting, and concentrated insulin products). As described previously, introducing floor stock product carries organizational risk, and pharmacy leaders must be confident with processes to prevent cross-contamination and regulatory noncompliance.

Risk Reduction Strategies

Floor Stock

Storing MDVs as floor stock may be useful with operational and technological limitations. When MDVs are stored as floor stock rather than patient-specific pens or patient-specific vials, there are several considerations for establishing safe handling practices. Compared to storage in central pharmacy or medication room refrigerators, MDVs should ideally be stored in an ADC to prevent delays in care and wrong drug errors. MDVs may be used for multiple patients when stored under the described conditions using proper aseptic technique and smaller volume vials (ie, 3 mL vials) to limit repeated vial access. ⁵ When MDVs are stored in ADCs, ISMP states that MDVs should be segregated in locked-lidded pockets to prevent the possibility of selecting the wrong insulin product for nurse preparation.

Additionally, barcode scanners and automatic label printers can be implemented to correctly identify insulin product, prepare patient-specific syringes away from patient care areas, and correctly identify the patient for medication administration. Patient labels are ideally employed in conjunction with BCMA when possible. ⁴ Floor stock should be limited to short acting insulin as these products carry a greater risk for wrong time errors. Subsequently, minimizing the availability of long acting, intermediate acting, and concentrated floor stock insulin reduces excess waste from vial loss, cross-contamination from multi-patient use, and risk of wrong drug errors. Advantages and disadvantages for floor stock dispensing are listed in Table 2.

Table 2.

Advantages and Disadvantages of Common Dispensing Strategies.

	Advantages	Disadvantages
Pharmacy dispensing of patient-specific vials or pens	• Low risk of wrong product error • Lower risk of wrong-patient error • Low operational pharmacy support required	• Highest risk for wrong time error • Highest risk of wrong dose error • Highest risk of cross-contamination
Pharmacy dispensing of patient-specific pre-drawn syringes	• Low risk of wrong dose error • Low risk of wrong product error • Lowest risk of wrong patient error • Lowest risk of waste • Lowest risk of cross-contamination • Lowest technological pharmacy support required	• High risk for wrong time error • Highest operational pharmacy support required
ADC patient-specific vials or pens	• Low risk of wrong time error • Low risk of cross contamination • Low risk of wrong product error • Low risk of wrong patient error	• High technological pharmacy support required • Highest risk of waste • Moderate risk of wrong dose error
Floor stock vials or pens	• Low risk of wrong time error • Lower risk of waste • Lowest operational pharmacy support required	• Highest technological pharmacy support required • Moderate risk of wrong patient error • Highest risk of wrong dose error • Highest risk of wrong product error • Highest risk of cross-contamination

ADC = automated dispensing cabinet.

Patient-Specific Vials

Utilizing patient-specific MDVs is a strategy to minimize the risk of cross-contamination or to mitigate operational limitations. Per the CDC, MDVs should be stored and punctured in a location away from patient care areas (eg, operating rooms, procedure carts, patient bays, and patient rooms). MDVs that do enter these areas shall be designated for that patient for continued use. ⁵ In institutions that do not have product barcoding or patient-specific labeling capability, designated vials may be dispensed from the central pharmacy or assigned from floor stock for patient use. Concerns with this approach include excess waste when a patient is discharged or when a vial is lost and the potential for wrong time errors when patient-specific vials are dispensed from the central pharmacy. To limit the potential for wrong drug errors, product availability for patient-specific vials assigned from floor stock should be limited to short acting insulin segregated in locked-lidded pockets with BCMA scanning when possible. Advantages and disadvantages for patient-specific vial dispensing are listed in Table 2.

Patient-Specific Dose

ISMP and TJC state that insulin doses should be provided in the most ready-to-use format for administration.^3,8 Pharmacy dispensing of patient-specific doses reduces the risk of wrong product and wrong dose errors. However, there are operational concerns to providing short acting insulin as patient-specific doses that incurs a risk of wrong time errors. Given that long acting, intermediate acting, and concentrated insulins are routinely scheduled, these doses should be prepared as patient-specific doses utilizing product barcode scanning in the pharmacy and dispensed to the floor in a ready-to-use format rather than as floor stock to limit the potential for wrong dose, wrong product, or wrong patient error. Advantages and disadvantages for patient-specific dose dispensing are listed in Table 2.

Recommendations for Safe insulin use

Short acting insulin may be dispensed in several ways, abiding by the proper risk reduction strategies in place. Floor stock vials are common, reduce departmental costs, and improve ease of use for sliding scale orders. The authors preferably recommend that institutions provide patient-specific, short acting insulin vials to comply with CDC guidance. Alternatively, due to the cost of vials, the authors also support institutions utilizing floor stock short acting insulin vials, assuming infection risks, wrong dose, and wrong drug errors are minimized through the use of technology. If staff are to use floor stock short acting insulin vials, institutions must be able to provide appropriately labeled syringes before entering the patient room.

The authors recommend that long acting and intermediate acting insulin be prepared in a patient-specific, ready-to-use format by the pharmacy. Floor stock vials of long acting and intermediate acting insulin are not recommended given the potential for product mix-up and wrong drug error. The pharmacist product verification process and pharmacy access to technology-assisted workflow (TAWF) confirm the right drug for the right patient. Administration errors with long acting and intermediate acting insulin may be more difficult to recognize and intervene to preclude harm. While this may mean more workload for the pharmacy, it avoids calculation errors by nursing, who are tasked with many other important tasks. The authors recommend that the pharmacy batch prepare all standing patient-specific long acting and intermediate acting insulin orders together for ease of workload and determine a standard administration time to successfully accomplish this.

At a minimum, the pharmacy must always prepare concentrated insulin in patient-specific doses to minimize the need for manipulation and calculation by nursing. Vials should never be stored on the patient care unit as floor stock. Given the risk of morbidity with wrong dose errors and infrequency of use, insulin pens for U-500 are preferred. Some institutions may utilize insulin pens due to the low operational pharmacy support required, patient and nurse satisfaction associated with administration, and minimal difference in cost relative to vials. ²¹ The authors preferably recommend that insulin pens be used only for U-500 concentrated insulin to reduce the risk of product mix-up. For example, in 2016, Brown and Hertig, ²⁸ reported in a survey of 474 institutions that approximately 30% of the survey respondents accounted that insulin pens had been used on more than 1 patient at least once in their institution. In institutions that do not possess the operational and technological capabilities to implement components of the described subcutaneous insulin dispensing best practices, patient-specific insulin pens may be an acceptable, provisional alternative for institutional use with the intent to align with dispensing best practices. Recommendations are summarized below in Table 3.

Table 3.

Summary of Recommendations for Subcutaneous Insulin Dispensing.

	Pharmacy patient-specific preparation	ADC patient-specific	ADC floor stock
Short acting		✓	✓
Intermediate acting	✓
Long acting	✓
Concentrated	✓ a

ADC = automated dispensing cabinet.

^aInsulin pen dispensed from pharmacy.

Conclusion

Subcutaneous insulin is one of the most commonly ordered medications in the hospital, yet there remains little consensus on best practices for dispensing insulin products. Waste and patient safety remain active concerns for this high-alert medication. While variation in practice is conditional to institutional resources, processes may be refined to ensure optimal usage. Institutions may use either MDVs or pens exclusively or a blend of pens and MDVs depending on pharmacy capability to absorb additional sterile compounding preparation and ADC inventory management capabilities. Thus, strategies for insulin dispensing should be formulated by class. In this review of subcutaneous insulin dispensing, recommendations are provided to refine institutional processes and emphasize patient safety for each class of insulin.