Insulin is a high risk drug with the potential to cause serious harm when not used correctly. Whilst historically most insulins contained 100units/ml there are now high-strength products containing up to 300units/ml (some imported products contain 500units/ml). These higher strength products have the potential for patient harm where they are prescribed, dispensed or administered incorrectly.

High strength insulin products currently available include:

  • Tresiba Pre-filled pen 200units/ml (Insulin degludec)
  • Humalog Kwikpen  200units/ml (Insulin lispro)
  • Toujeo Solostar 300units/ml (Insulin glargine)

High strength insulins are effective treatments for diabetic patients who require high insulin doses to control their blood glucose, and the volume of the injection causes a clinical issue such as:

  • injection site leakage.
  • pain or discomfort when injecting.
  • development of lipodystrophy.

Toujeo can also be used where patients suffer from an unacceptable frequency of nocturnal hypoglycaemia, or where once daily insulin dosing is required for patients needing assistance to administer their insulin.

How to reduce risks associated with high strength insulin preparations

Actions to mitigate risks associated with high strength insulins can be categorised as risks relating to prescribing, supply, storage, administration and governance.

When prescribing high strength insulin prescribers are encouraged to:

  • Always prescribe by brand name and strength where multiple strengths of the same insulin exist.
  • Write the word “units” in full, do not abbreviate to U or IU.
  • Circle the strength of a high-strength insulin.

Pharmacists who receive prescriptions for high strength insulins either written generically or containing abbreviations should ask the prescriber to write future prescriptions by brand or with doses and/or strengths written in full.

Other considerations when initiating patients onto high strength insulin include:

  • Toujeo, glargine 300units/ml, and insulin glargine 100units/ml are not bioequivalent and therefore not interchangeable without dosage adjustment.
  • Dose adjustment is not required where patients are transferred from Humalog 100units/ml to Humalog 200units/ml[1] as the unit counters on the pens are equivalent.

When supplying high strength insulins pharmacists should ensure that:

  • the patient/carer confirms the insulin supplied is what they are expecting.
  • the product prescribed meets the product in the patient’s insulin passport.
  • patients transferred from standard strength insulin to high strength insulin should be advised to follow the revised dosage as advised by the prescriber.
  • patients are encouraged to read the patient information leaflet and associated patient education material.

Storing dispensed insulin in clear bags in the fridge makes the process of confirming insulin products with the patient or carer easier, it also makes selecting dispensed insulin on collection simpler.

Risks associated with the wrong selection of high strength insulin during the dispensing process can be reduced by:

  • Segregating high strength insulins within the fridge.
  • Using shelf edge labels or stickers to highlight high strength products.

Safe administration of high strength insulin can be supported by advising patients to:

  • Only administer insulin with the appropriate pen device.
  • Only to administer insulin as they have been trained.
  • Never extract insulin from a pen device with a needle and syringe.
  • Closely monitor their blood glucose to ensure glucose control when switching from standard strength to high strength insulin.

In addition to reducing risks associated with prescribing, dispensing and administration pharmacists can support patients using high strength insulins by:

  • Ensuring patients know there is more than one strength of their insulin available.
  • Advising patients to always check the correct product has been supplied irrespective of which pharmacy supplies their insulin.

In addition to the safety risks associated with errors in prescribing, dispensing or administration of high strength insulins there is also evidence of safety events associated with the extraction of insulin from pen devices with an insulin syringe. Insulin syringes are calibrated for 100 units/ml which means that extracting high strength insulin from pens or cartridges can result in administration of an insulin overdose. A Patient Safety update was issued by MHRA in November 2016[2] advising that insulin should not be withdrawn from insulin pens or cartridges for administration using an insulin syringe.