Clinical effects of once-weekly exenatide for the treatment of type 2 diabetes mellitus.

PURPOSE: The pharmacology, pharmacokinetics, clinical efficacy, adverse effects, administration, dosage, place in therapy, and cost of extended-release exenatide are reviewed. SUMMARY: Regular-release exenatide has a half-life of 2.4 hours and is administered twice daily. In order to allow for once-weekly administration, exenatide was encapsulated in poly(lactic-co-glycolic acid) microspheres, a biodegradable polymer. After subcutaneous injection, the microspheres slowly degrade, and the drug is released. A single injection of extended-release exenatide reaches maximum plasma concentration after 4-8 hours and remains at therapeutic levels for 8-16 hours, depending on the dosage. Based on the pharmacokinetics of a single dose, researchers determined that 0.8- and 2-mg once-weekly doses were likely to maintain therapeutic levels in the serum. Patients who used extended-release exenatide monotherapy had significantly lower glycosylated hemoglobin (HbA1c) levels and lost more weight than those receiving sitagliptin or pioglitazone (p < 0.05). In combination with metformin, extended-release exenatide reduced HbA1c levels more than did insulin glargine. This new formulation reduced HbA1c levels by 1.5-1.9%, fasting blood glucose concentrations by 31-42 mg/dL, and weight by 2.3-3.7 kg. The most common adverse events were injection-site reactions and transient nausea. Postmarketing reports have described acute pancreatitis and acute necrotizing or hemorrhagic pancreatitis in patients treated with exenatide. The published average wholesale price for a one-month supply of extended-release exenatide 2 mg is $388. CONCLUSION: Extended-release exenatide taken once weekly is an effective second-line therapy for patients with type 2 diabetes who have not achieved glycemic goals with metformin alone.