Exenatide injection, prefilled pen (Byetta^®) - Type 2 diabetes mellitus

SMC recommendation
Advice: following a full submission
Exenatide (Byetta^® ) is accepted for restricted use within NHS Scotland for the treatment of type 2 diabetes mellitus in combination with metformin and/or sulphonylureas in patients who have not achieved adequate glycaemic control on maximally tolerated doses or these oral therapies.
It has shown non-inferiority to two insulin regimens with which it has been compared and has a beneficial effect on weight.  It is restricted to use as an alternative to insulin in patients who have failed treatment on metformin and/or sulphonylureas and in whom insulin would be the next treatment option.
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• Exenatide is the first of a new class of antidiabetic agents known as incretin mimetics.  It acts by stimulating glucose-dependent insulin secretion, suppressing glucagon, delaying gastric emptying and reducing food intake.
• Exenatide is administered by subcutaneous (sc) injection at a dose of 5mcg or 10mcg twice daily up to one hour before meals.  Unlike insulin, exenatide dose not require frequent blood glucose monitoring or continual dose titration.
• Exenatide has shown similar reductions in HbA_1c as insulin glargine and biphasic insulin aspart in 26 and 52-week open-label comparator studies in patients inadequately controlled on combination therapy with metformin and a sulphonylurea.  Unlike insulin, exanatide is associated with weight loss (4.4kg reduction versus baseline at 82 weeks).
• The most common adverse-effects of exenatide are gastrointestinal with nausea and vomiting affecting up to 50% of patients.  The incidence of severe hypoglycaemia appears to be low and occurs mainly in patients also on a sulphonylurea.  If exenatide is added to sulphonylurea therapy, the SPC recommends that a reduction in sulphonylurea dose should be considered and blood glucose monitoring may become necessary.  Exenatide may reduce the extent and rate of absorption of some oral medicines – refer to SPC for further details.
• Exenatide is not currently licensed for use in combination with glitazones which are commonly used in practice.  There are no comparative data on exenatide versus glitazones in patients inadequately controlled on metformin and/or sulphonylureas are unavailable.  Long-term studies are needed to determine the effect of exenatide on disease-related morbidity and mortality.
• At a cost of £830 per patient per year, exenatide is considerably more expensive than glitazones or insulin.
• There are currently no specific driving restrictions for patients with diabetes who are prescribed exenatide.
• A local protocol is available to support the prescribing of exenatide sc injection.
• Locally, exanatide sc injection is restricted to type 2 diabetic patients who have failed to achieve glycaemic control on metformin and/or sulphonylureas and in whom glitazones are unsuitable (eg due to heart failure, hepatic impairment or where rapid glycaemic control is required) and who would otherwise move to insulin therapy.  Treatment should be under the direction of the diabetic clinic.