Exenatide. From the Gila monster to you. Exenatide is the first of a new class of drugs known as "incretin mimetics" that can enhance your blood glucose control.
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BACKGROUND: Exenatide (exendin-4) exhibits dose-dependent glucoregulatory activity, but causes dose-limiting nausea and vomiting. This study was designed to formally assess the possibility of inducing tolerance to the side effects of nausea and vomiting at therapeutic doses of exenatide, using a dose-escalation methodology. METHODS: In this two-arm, triple-blind, multicenter study, 123 subjects with type 2 diabetes were enrolled and randomized; 99 (80.5%) of them completed the study. Subjects in the exenatide-primed arm received subcutaneous exenatide, starting at 0.02 micro g/kg three times a day (TID) and increasing in 0.02 micro g/kg per dose increments every 3 days for 35 days. Subjects in the exenatide-naive arm received placebo TID for 35 days. At the end of this 35-day regimen, subjects in both arms received the same highest dose of exenatide (0.24 micro g/kg TID) for 3 days. Thus, the exenatide-naive arm received exenatide for the first time on Day 35. RESULTS: The exenatide-primed arm had a lower proportion of subjects experiencing nausea and vomiting in response to exposure to the highest dose of exenatide (27 vs 56% in the exenatide-naive arm; p = 0.0018). Kaplan-Meier estimates of cumulative incidence were 0.28 in the exenatide-primed arm, compared with 0.68 in the exenatide-naive arm (p </= 0.001). As predicted by the study design, fewer subjects in the exenatide-primed arm reported severe nausea (29%) and vomiting (10%) than those in the exenatide-naive arm (48 and 31%, respectively). In the exenatide-primed arm, fasting serum glucose progressively declined over the first 35 days of dosing, but was unchanged in the exenatide-naive arm (placebo phase) during the same interval. CONCLUSION: Gradual dose-escalation of exenatide successfully reduced the proportion of subjects experiencing dose-limiting nausea and vomiting, with no loss of glucoregulatory activity, thus demonstrating the value of gradual dose-escalation in mitigating the gastrointestinal side effects of exenatide.
Exenatide is a 39 amino acid incretin mimetic for the treatment of type 2 diabetes, with glucoregulatory activity similar to glucagon-like peptide-1 (GLP-1). Exenatide is a poor substrate for the major route of GLP-1 degradation by dipeptidyl peptidase-IV, and displays enhanced pharmacokinetics and in vivo potency in rats relative to GLP-1. The kidney appears to be the major route of exenatide elimination in the rat. We further investigated the putative sites of exenatide degradation and excretion, and identified primary degradants. Plasma exenatide concentrations were elevated and sustained in renal-ligated rats, when compared to sham-operated controls. By contrast, exenatide elimination and degradation was not affected in rat models of hepatic dysfunction. In vitro, four primary cleavage sites after amino acids (AA)-15, -21, -22 and -34 were identified when exenatide was degraded by mouse kidney membranes. The primary cleavage sites of exenatide degradation by rat kidney membranes were after AA-14, -15, -21, and -22. In rabbit, monkey, and human, the primary cleavage sites were after AA-21 and -22. Exenatide was almost completely degraded into peptide fragments <3 AA by the kidney membranes of the species tested. The rates of exenatide degradation by rabbit, monkey and human kidney membranes in vitro were at least 15-fold slower than mouse and rat membranes. Exenatide (1-14), (1-15), (1-22), and (23-39) were not active as either agonists or antagonists to exenatide in vitro. Exenatide (15-39) and (16-39) had moderate-to-weak antagonist activity compared with the known antagonist, exenatide (9-39). In conclusion, the kidney appears to be the primary route of elimination and degradation of exenatide.
BACKGROUND: Physicians may use either insulin or exenatide injections for patients with type 2 diabetes mellitus who have poor glycemic control despite taking oral blood glucose-lowering drugs. OBJECTIVE: To compare effects of exenatide and insulin glargine on glycemic control in patients with type 2 diabetes mellitus that is suboptimally controlled with metformin and a sulfonylurea. DESIGN: 26-week multicenter, open-label, randomized, controlled trial. SETTING: 82 outpatient study centers in 13 countries. PATIENTS: 551 patients with type 2 diabetes and inadequate glycemic control (defined as hemoglobin A1c level ranging from 7.0% to 10.0%) despite combination metformin and sulfonylurea therapy. INTERVENTION: Exenatide, 10 microg twice daily, or insulin glargine, 1 daily dose titrated to maintain fasting blood glucose levels of less than 5.6 mmol/L (<100 mg/dL). MEASUREMENTS: Hemoglobin A1c level, fasting plasma glucose level, body weight, 7-point self-monitored blood glucose, standardized test-meal challenge, safety, and tolerability. RESULTS: Baseline mean hemoglobin A1c level was 8.2% for patients receiving exenatide and 8.3% for those receiving insulin glargine. At week 26, both exenatide and insulin glargine reduced hemoglobin A1c levels by 1.11% (difference, 0.017 percentage point [95% CI, -0.123 to 0.157 percentage point]). Exenatide reduced postprandial glucose excursions more than insulin glargine, while insulin glargine reduced fasting glucose concentrations more than exenatide. Body weight decreased 2.3 kg with exenatide and increased 1.8 kg with insulin glargine (difference, -4.1 kg [CI, -4.6 to -3.5 kg]). Rates of symptomatic hypoglycemia were similar, but nocturnal hypoglycemia occurred less frequently with exenatide (0.9 event/patient-year versus 2.4 events/patient-year; difference, -1.6 events/patient-year [CI, -2.3 to -0.9 event/patient year]). Gastrointestinal symptoms were more common in the exenatide group than in the insulin glargine group, including nausea (57.1% vs. 8.6%), vomiting (17.4% vs. 3.7%) and diarrhea (8.5% vs. 3.0%). LIMITATIONS: The trial was open-label and did not assess clinical complications related to diabetes. Of the 551 participants, 19.4% of those receiving exenatide and 9.7% of those receiving insulin glargine withdrew from the study. Only 21.6% of the insulin glargine group and 8.6% of the exenatide group achieved the target level for fasting plasma glucose of less than 5.6 mmol/L (<100 mg/dL). CONCLUSIONS: Exenatide and insulin glargine achieved similar improvements in overall glycemic control in patients with type 2 diabetes that was suboptimally controlled with oral combination therapy. Exenatide was associated with weight reduction and had a higher incidence of gastrointestinal adverse effects than insulin glargine.
Exenatide [AC002993, AC2993A, AC 2993, LY2148568, exendin 4], a glucagon-like peptide-1 (GLP-1) agonist, is a synthetic exendin 4 compound under development with Amylin Pharmaceuticals for the treatment of type 2 diabetes. Both exendin 4 and its analogue, exendin 3, are 39-amino acid peptides isolated from Heloderma horridum lizard venom that have different amino acids at positions 2 and 3, respectively. Exendins are able to stimulate insulin secretion in response to rising blood glucose levels, and modulate gastric emptying to slow the entry of ingested sugars into the bloodstream. Amylin Pharmaceuticals acquired exclusive patent rights for the two exendin compounds (exendin 3 and exendin 4) from the originator, Dr John Eng (Bronx, NY, US). On 20 September 2002, Amylin and Eli Lilly signed a collaborative agreement for the development and commercialisation of exenatide for type 2 diabetes. Under the terms of the agreement, Eli Lilly has paid Amylin a licensing fee of 80 million US dollars and bought Amylin's stock worth 30 million US dollars at 18.69 US dollars a share. After the initial payment, Eli Lilly will pay Amylin up to 85 US dollars million upon reaching certain milestones and also make an additional payment of up to 130 million US dollars upon global commercialisation of exenatide. Both companies will share the US development and commercialisation costs, while Eli Lilly will pick up up to 80% of development costs and all commercialisation costs outside the US. Amylin and Eli Lilly will equally share profit from sales in the US, while Eli Lilly will get 80% of the profit outside the US and Amylin will get the rest. This agreement has also enabled Amylin to train its sales force to co-promote Lilly's human growth hormone Humatrope. Alkermes will receive research and development funding and milestone payments, and also a combination of royalty payments and manufacturing fees based on product sales. Alkermes undertakes the responsibility for the development of several initial formulations of the long-acting drug and manufacturing of the final product, while Amylin will be responsible for clinical trials, regulatory filings and worldwide marketing. The goal of the exenatide LAR programme is to develop a once-a-month injectable formulation of exenatide. In November 2003, Amylin announced positive results from the second of three pivotal, phase III studies that evaluated the effects of exenatide in combination with sulfonylureas in 377 randomised patients with type 2 diabetes. The design of the study was similar to that from the first study. The final third phase III study of exenatide was completed in November 2003. This study investigated the effects of exenatide in combination with metformin and sulfonylureas. Amylin and Eli Lilly announced that all of the pivotal phase III trials met the primary glucose control endpoint as measured by glycosylated haemoglobin. An NDA submission for exenatide is projected for mid-2004. A phase II, dose-ascending study in patients with type 2 diabetes was initiated in June 2002. This multicentre (US), double-blind, placebo-controlled study evaluated the safety, tolerability and the pharmacokinetic profile of exenatide LAR in up to 100 patients with type 2 diabetes. A phase I study of exenatide LAR began in Europe in March 2001 and was completed in Q3 2001. A long-acting, sustained-release formulation of exenatide lowered both pre- and post-meal glucose concentration during a 24h period in patients with type 2 diabetes. In November 2002, analysts at Prudential Financial estimated that exenatide, pending approval, has the potential to reach sales of 477 million US dollars in 2006.
BACKGROUND: Exenatide is the first of a new class of agents known as incretin mimetics that are in development for the treatment of type 2 diabetes. Exenatide has been shown to reduce fasting and postprandial glucose in patients with type 2 diabetes, as well as provide sustained reductions in hemoglobin A 1c (HbA 1c). This study was designed to assess the dose dependencies of the glucoregulatory effects and tolerability of exenatide when added to diet and exercise or metformin monotherapy in patients with type 2 diabetes. METHODS: In this randomized, triple-blinded, placebo-controlled Phase 2 clinical trial, 156 patients were randomized to placebo or exenatide at 2.5, 5.0, 7.5, or 10.0 microg administered b.i.d. for 28 days. RESULTS: After 28 days of therapy, exenatide was associated with significant (P < 0.0001, linear contrast testing), dose-dependent reductions in HbA 1c (0.1 +/- 0.1%, -0.3 +/- 0.1%, -0.4 +/- 0.1%, +/-0.5 +/- 0.0%, and -0.5 +/- 0.1% for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively) and significant (P = 0.0006, linear contrast testing) reductions in fasting plasma glucose (+6.8 +/- 4.1, -20.1 +/- 5.2, -21.2 +/- 3.9, -17.7 +/- 4.8, and -17.3 +/- 4.4 mg/dL for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively) by Day 28. These reductions were similar for patients treated with diet/exercise and those treated with metformin. In addition, patients receiving exenatide exhibited dose-dependent reductions in body weight (0.0 +/- 0.3, -0.7 +/- 0.3, -0.7 +/- 0.2, -1.4 +/- 0.3, and -1.8 +/- 0.3 kg for placebo and 2.5, 5.0, 7.5, and 10.0 microg b.i.d. exenatide, respectively; P < 0.01 for 7.5 and 10.0 microg b.i.d. exenatide doses compared with placebo) at Day 28. The most common adverse event was mild-to-moderate nausea that was dose-dependent (seven of 123 patients randomized to exenatide withdrew from the study because of gastrointestinal effects). CONCLUSIONS: Exenatide dose-dependently improved glycemic control and reduced body weight over 28 days in patients with type 2 diabetes treated with diet/exercise or metformin.
OBJECTIVE: To evaluate available literature characterizing the pharmacology, pharmacokinetics, drug interactions, efficacy, and safety of exenatide in patients with type 2 diabetes. DATA SOURCES: A PubMed database search (1966-May 2006) was conducted, using exenatide as the search term. The manufacturer's prescribing information was also used. STUDY SELECTION AND DATA EXTRACTION: English-language articles were selected and data were extracted with a focus on clinical outcomes associated with the treatment of patients with type 2 diabetes. DATA SYNTHESIS: Exenatide exerts a glucoregulatory effect by various mechanisms including secretion of glucose-dependent insulin, suppression of inappropriately high glucagon levels in patients with type 2 diabetes, delayed gastric emptying, and reduction of food intake. In placebo-controlled clinical studies, plasma exenatide concentrations appeared to exhibit dose-proportional kinetics, reaching peak plasma levels between 2 and 3 hours after a single subcutaneous injection. Exenatide's elimination half-life ranged from 3.3 to 4.0 hours, and the time to reach maximum concentration was about 2 hours. Interactions between exenatide and agents such as digoxin and lisinopril were not considered significant. In Phase III trials, exenatide demonstrated significant reduction of hemoglobin A1c levels from baseline and compared with placebo after 30 weeks of treatment in patients unable to achieve optimal glycemic control with metformin, a sulfonylurea, or oral combination therapy (0.4-0.9%). Patients' weight decreased with exenatide (0.9-2.8 kg), but adverse gastrointestinal (GI) events were common. Exenatide combined with thiazolidonediones, D-phenylalanine derivatives, meglitinides, or alpha glucosidase inhibitors has not been studied. CONCLUSIONS: Clinical trials have demonstrated that exenatide improves glycemic control when added to sulfonylureas and metformin, and it may be an alternative to insulin glargine in patients requiring additional therapy. Hypoglycemia has been encountered in clinical trials of exenatide, especially upon initiation of therapy with sulfonylureas (not with metformin); close patient monitoring is therefore recommended. Further studies should assess the impact of exenatide on clinical outcomes such as micro- and macrovascular disease.
AIMS/HYPOTHESIS: The aim of this 52-week, open-label, non-inferiority trial was to compare the safety and efficacy of exenatide (an incretin mimetic) with that of biphasic insulin aspart. MATERIALS AND METHODS: Patients on metformin and a sulfonylurea were randomised to exenatide (n = 253; 5 microg twice daily for 4 weeks, 10 microg thereafter) or biphasic insulin aspart (n = 248; twice-daily doses titrated for optimal glucose control), while continuing with metformin and sulfonylurea treatment. RESULTS: Glycaemic control achieved with exenatide was non-inferior to that achieved with biphasic insulin aspart (mean+/-SEM, HbA(1c) change: exenatide -1.04 +/- 0.07%, biphasic insulin aspart -0.89 +/- 0.06%; difference -0.15 [95% CI -0.32 to 0.01]%). Exenatide-treated patients lost weight, while patients treated with biphasic insulin aspart gained weight [between-group difference -5.4 (95% CI -5.9 to -5.0) kg]. Both treatments reduced fasting serum glucose (exenatide -1.8 +/- 0.2 mmol/l, p < 0.001; biphasic insulin aspart -1.7 +/- 0.2 mmol/l, p < 0.001). Greater reductions in postprandial glucose excursions following morning (p < 0.001), midday (p = 0.002) and evening meals (p < 0.001) were observed with exenatide. The withdrawal rate was 21.3% (54/253) for exenatide and 10.1% (25/248) for biphasic insulin aspart. Nausea (33% incidence, 3.5% discontinuation) was the most common adverse event observed with exenatide. CONCLUSIONS/INTERPRETATION: Exenatide treatment resulted in HbA(1c) reduction similar to biphasic insulin aspart and provided better postprandial glycaemic control, making it a potential alternative for the treatment of type 2 diabetes. Treatment with biphasic insulin aspart was associated with weight gain and lower risk of adverse gastrointestinal events. Although the availability of glucose-lowering agents associated with weight reduction may be considered a therapeutic advance, the long-term implications of progressive weight reduction observed with exenatide have yet to be defined.
BACKGROUND: Exenatide is a subcutaneously injected incretin mimetic. It is indicated as adjunctive therapy to improve glycemic control in patients with type 2 diabetes mellitus (T2DM) who are already receiving therapy with metformin, a sulfonylurea, or both but continue to have suboptimal glycemic control. OBJECTIVE: This article reviews available information on the clinical pharmacology, comparative efficacy, tolerability, drug interactions, contraindications and precautions, dosage and administration, availability and storage, and cost of exenatide. METHODS: MEDLINE (1966-April 2006) and Web of Science (1995-April 2006) were searched for original research and review articles published in the English language. The search terms used were exenatide, exendin-4, glucagon-Like peptide-1, GLP-1, and incretin mimetic. The reference lists of identified articles were also consulted, as was selected information from the package insert for exenatide. All relevant comparative efficacy studies that were available in published form were included in the review. RESULTS: Naturally occurring incretins, such as glucagon-like peptide-1 (GLP-1), exhibit insulinotropic properties after release into the circulation from the gut. As a GLP-1 agonist, exenatide improves glucose homeostasis by mimicking the actions of naturally occurring GLP-1. It improves glycemic control by reducing fasting and postprandial glucose concentrations through a combination of known mechanisms, including glucose-dependent insulin secretion, restoration of first-phase insulin response, regulation of glucagon secretion, delaying gastric emptying, and decreasing food intake. Three Phase III comparative efficacy trials were identified that enrolled a total of 1,446 patients who received exenatide 5 pg SC BID, exenatide 10 mug SC BID, or placebo for 30 weeks in addition to their existing therapy with metformin, sulfonylurea, or both. In these trials, the addition of exenatide was associated with significant reductions in glycosylated hemoglobin (HbA(1c)) values (P < 0.001-P < 0.002), greater proportions of patients achieving an HbA(1c) 10% of patients receiving exenatide were hypoglycemia (19.6%), diarrhea (12.8%), and vomiting (12.8%). CONCLUSIONS: During clinical trials, exenatide added to existing metformin and/or sulfonylurea therapy in patients with T2DM reduced fasting and postprandial glucose concentrations, with improvements in HbA(1c) and modest weight loss. The main adverse effect associated with exenatide therapy was nausea.
Exenatide (exendin-4) is an incretin mimetic with potential antidiabetic activity. This study examined the effects of a continuous subcutaneous (SC) infusion of exenatide (0.2, 0.4, 0.6, or 0.8 microg/kg/day) or placebo (PBO) on glycemic control over 23 h intervals. Twelve subjects with type 2 diabetes treated with metformin and/or diet received 10 infusions (4 exenatide, 6 PBO) on consecutive days. Exenatide was given in a dose-increasing design with at least one placebo infusion between each exenatide infusion, and with meals and a snack provided during the first 14 h of infusion. Plasma exenatide concentrations were dose-proportional. Plasma glucose (4-23 h) was lower in all exenatide arms compared to placebo (p<0.0001). The change in insulin/glucagon ratio and amylin concentrations from pre-infusion to post-infusion was increased (p<0.005, p<0.05, respectively) in the combined exenatide arms, but remained unchanged in the placebo groups. Nausea and vomiting were the most common treatment emergent adverse events. Exenatide infusion also appeared to have positive effects on beta-cell and alpha-cell function as measured by proinsulin/insulin ratios and mean glucagon concentrations. In summary, exenatide lowered plasma glucose during both prandial and fasting states when delivered as a continuous SC infusion over twenty-three hours, suggesting that exenatide can provide day-long glycemic control in patients with type 2 diabetes.
PURPOSE: The pharmacology and tolerability of exenatide in patients with type 2 diabetes mellitus were studied. METHODS: Two randomized, single-blind, placebo-controlled studies were conducted. Treatment with oral antidiabetic agents was stopped 14 days before study initiation. In the first study (study A), eight subjects received placebo, 0.1-, 0.2-, 0.3-, and either 0.4-microg/kg exenatide or placebo five minutes before a meal combined with liquid acetaminophen (to assess the rate of gastric emptying) on days 1, 3, 5, 7, and 9. In the second study (study B), subjects received a single s.c. dose of exenatide or placebo on consecutive days. Part 1 of study B used exenatide doses of 0.01 and 0.1 microg/ kg; 0.02-, 0.05-, and 0.1-microg/kg doses were given in part 2. After an overnight fast, the study drug was injected 15 minutes before a meal (part 1) and before a meal and acetaminophen (part 2). Parts 1 and 2 of study B enrolled six and eight patients, respectively. RESULTS: In both studies, plasma exenatide pharmacokinetic profiles appeared dose proportional. Exenatide doses of 0.02-0.2 microg/kg dose-dependently lowered postprandial glucose excursions. Exenatide suppressed postprandial plasma glucagon and slowed gastric emptying. There were no serious adverse events and no patient withdrawals related to treatment. Nausea and vomiting were the most common adverse events and were mild to moderate in severity at doses ranging from 0.02 to 0.2 microg/kg. CONCLUSION: Administration of preprandial exenatide by s.c. injection resulted in dose-proportional exenatide pharmacokinetics and antidiabetic pharmacodynamic activity. At doses ranging from 0.02 to 0.2 microg/kg, exenatide dose-dependently reduced postprandial plasma glucose excursion by insulinotropism, suppression of plasma glucagon, and slowing of gastric emptying.
AIMS: Exenatide is an incretin mimetic whose effect on glycaemic control in patients with Type 2 diabetes is currently under investigation. This study assessed the effect of injection time relative to a standardized meal on postprandial pharmacodynamics of exenatide in patients with Type 2 diabetes. METHODS: Eighteen patients participated in this single-centre, open-label, placebo-controlled, randomized, six-way crossover study. Patients received subcutaneous injections of either placebo (-15 min) or 10 microg of exenatide at -60, -15, 0, +30 or +60 min relative to a standardized breakfast meal on six consecutive days. Serial blood samples were assayed for plasma glucose and insulin concentrations. RESULTS: For all exenatide treatments, incremental postprandial glucose area under the postprandial plasma glucose curve from zero to 6 h (AUC0-6 h) was significantly reduced compared with placebo. When exenatide was administered before (-60, -15 min) or with the meal (0 min), peak postprandial glucose concentrations were significantly decreased (P < 0.0001 for all treatments) compared with placebo. Post-meal exenatide administration (+30, P < 0.05; +60 min, P = 0.21) resulted in smaller peak glucose reductions and in some patients transient low plasma glucose concentrations were reported. Peak plasma insulin concentrations in the pre-meal treatments were significantly lower than placebo (P < 0.05 for all treatments), while post-meal dosing groups exhibited a trend towards higher insulin peaks compared with placebo. The most common adverse events related to exenatide were headache, nausea, dyspepsia and vomiting, and were generally of mild-to-moderate intensity. CONCLUSIONS: In this study, all exenatide treatments demonstrated reductions in postprandial plasma glucose excursions compared with placebo. Pre-meal and with meal administration of exenatide produced greater reduction of postprandial glucose excursions compared with post-meal administration. These data support flexible dosing of exenatide at any time within 60 min before a meal.
BACKGROUND: Exenatide (exendin-4) is an incretin mimetic currently marketed as an antidiabetic agent for patients with type 2 diabetes. In preclinical models, a reduction in body weight has also been shown in low-fat-fed, leptin receptor-deficient rodents. OBJECTIVE: To more closely model the polygenic and environmental state of human obesity, we characterized the effect of exenatide on food intake and body weight in high-fat-fed, normal (those with an intact leptin signaling system) rodents. As glucagon-like peptide-1 receptor agonism has been found to elicit behaviors associated with visceral illness in rodents, we also examined the effect of peripheral exenatide on kaolin consumption and locomotor activity. METHODS AND RESULTS: High-fat-fed C57BL/6 mice and Sprague-Dawley rats were treated with exenatide (3, 10 and 30 microg/kg/day) for 4 weeks via subcutaneously implanted osmotic pumps. Food intake and body weight were assessed weekly. At 4 weeks, body composition and plasma metabolic profiles were measured. Kaolin consumption and locomotor activity were measured in fasted Sprague-Dawley rats following a single intraperitoneal injection of exenatide (0.1-10 microg/kg). Exenatide treatment in mice and rats dose-dependently decreased food intake and body weight; significant reductions in body weight gain were observed throughout treatment at 10 and 30 microg/kg/day (P<0.05). Decreased body weight gain was associated with a significant decrease in fat mass (P<0.05) with sparing of lean tissue. Plasma cholesterol, triglycerides and insulin were also significantly reduced (P<0.05). Exenatide at 10 microg/kg significantly reduced food intake (P<0.05) but failed to induce kaolin intake. In general, locomotor activity was reduced at doses of exenatide that decreased food intake, although a slightly higher dose was required to produce significant changes in activity. CONCLUSION: Systemic exenatide reduces body weight gain in normal, high-fat-fed rodents, a model that parallels human genetic variation and food consumption patterns, and may play a role in metabolic pathways mediating food intake.
BACKGROUND: Islet transplantation can reduce or eliminate the need for insulin in patients with type 1 diabetes. Exenatide is a long acting analogue of Glucagon-like peptide-1 (GLP-1) that augments glucose induced insulin secretion, and may increase beta cell mass. We evaluated the effect of exenatide on insulin secretion after islet transplantation. METHODS: Eleven C-peptide positive islet cell recipients with elevated glucose levels were treated with exenatide for three months. Response was assessed by insulin requirements, meal tolerance tests, and hyperglycemic glucose clamps. RESULTS: Ten patients responded to exenatide. Two patients who had not restarted insulin achieved good glycemic control and one patient who had received 5500 IE/kg in first islet infusion was able to stop insulin. Seven other patients decreased their insulin dose by 39% on exenatide. Hyperglycemic clamp studies showed a rise in second phase insulin release (before exenatide: 246+/-88 pM; during exenatide: 644+/-294 pM, P<0.01). Meal tolerance studies before and one month after stopping exenatide did not show a difference in glucose or C-peptide values. Nausea and vomiting were the major side effects. CONCLUSIONS: Exenatide stimulates insulin secretion in islet transplant recipients. It reduces insulin dose in some patients and may delay the need to resume insulin in others. We did not find any evidence of a trophic effect on islets.
AIM: The ability of the incretin mimetic exenatide to improve glycaemic control and reduce body weight was assessed over 82 weeks in patients with type 2 diabetes failing to achieve glycaemic control with maximally effective doses of metformin. METHODS: In this interim 82-week analysis, 150 (total cohort) of an eligible population of 183 patients opted to continue exenatide treatment in an uncontrolled open-label extension of a 30-week double-blind, placebo-controlled trial. Of these, 92 patients (completer cohort) achieved 82 weeks of exenatide therapy. Patients continued metformin throughout the study. RESULTS: At the end of the placebo-controlled trial, exenatide resulted in an haemoglobin A1c (HbA1c) reduction from baseline of -1.0 +/- 0.1% (mean +/- SE) (exenatide treatment arms), with durable HbA1c reductions after 82 weeks of -1.3 +/- 0.1%. The percent of patients who achieved HbA1c < or = 7% at weeks 30 and 82 was 46 and 59% respectively. After 30 weeks, exenatide caused a reduction in weight from baseline of -3.0 +/- 0.6 kg, with a progressive reduction in weight of -5.3 +/- 0.8 kg after 82 weeks. In addition, exenatide treatment produced clinically significant improvements in cardiovascular risk factors after 82 weeks. The most frequent adverse event after 30 and 82 weeks of exenatide was nausea, which was generally of mild-or-moderate intensity. It decreased in incidence after initiation in the controlled trial and the uncontrolled open-label extension. Hypoglycaemia was rare, with no severe events. CONCLUSION: Exenatide was generally well tolerated, producing a durable reduction in HbA1c and a progressive reduction in weight over 82 weeks in patients with type 2 diabetes failing to achieve glycaemic control with metformin.
AIMS/HYPOTHESIS: Exenatide (exendin-4) injected subcutaneously twice daily reduces glycaemic deterioration in diabetic fatty Zucker (ZDF) rats and reduces HbA1c in humans with type 2 diabetes. Because tachyphylaxis may develop with continuous peptide exposure, we examined the activity of a long-acting-release (LAR) formulation of exenatide on HbA1c, insulin sensitivity and beta cell secretion in ZDF rats. METHODS: Single subcutaneous injections of a poly-lactide-glycolide microsphere suspension (3% peptide) containing 0, 1, 10, 100, 1,000, 3,000 or 9,000 mug exenatide were administered to 9-week-old ZDF rats with matched initial HbA1c values (n=7 rats/group). RESULTS: In contrast to the progressive 3.22+/-0.42% increase in HbA1c in control ZDF rats observed over 28 days, single exenatide-LAR injections dose-proportionally prevented such glycaemic deterioration (median effective dose 74 microg+/-0.1 log per rat; median effective concentration 52 pmol/l+/-0.06 log). Hyperinsulinaemic-euglycaemic clamp procedures incorporating an intraclamp glucose challenge performed 28 days after treatment revealed increases in beta cell response to the glucose challenge at lower exenatide-LAR doses, and up to a 2.1-fold increase in insulin sensitivity at higher exenatide-LAR doses. CONCLUSIONS/INTERPRETATION: The finding that a single dose of exenatide-LAR enhanced glucose control for 28 days in the ZDF rat model of type 2 diabetes suggests that tachyphylaxis is unlikely to be a feature of exenatide-LAR preparations, and supports further clinical exploration.
CONTEXT: First-phase insulin secretion (within 10 min after a sudden rise in plasma glucose) is reduced in type 2 diabetes mellitus (DM2). The incretin mimetic exenatide has glucoregulatory activities in DM2, including glucose-dependent enhancement of insulin secretion. OBJECTIVE: The objective of the study was to determine whether exenatide can restore a more normal pattern of insulin secretion in subjects with DM2. DESIGN: Fasted subjects received iv insulin infusion to reach plasma glucose 4.4-5.6 mmol/liter. Subjects received iv exenatide (DM2) or saline (DM2 and healthy volunteers), followed by iv glucose challenge. PATIENTS: Thirteen evaluable DM2 subjects were included in the study: 11 males, two females; age, 56 +/- 7 yr; body mass index, 31.7 +/- 2.4 kg/m2; hemoglobin A1c, 6.6 +/- 0.7% (mean +/- sd) treated with diet/exercise (n = 1), metformin (n = 10), or acarbose (n = 2). Controls included 12 healthy, weight-matched subjects with normal glucose tolerance: nine males, three females; age, 57 +/- 9 yr; and body mass index, 32.0 +/- 3.0 kg/m2. SETTING: The study was conducted at an academic hospital. MAIN OUTCOME MEASURES: Plasma insulin, plasma C-peptide, insulin secretion rate (derived by deconvolution), and plasma glucagon were the main outcome measures. RESULTS: DM2 subjects administered saline had diminished first-phase insulin secretion, compared with healthy control subjects. Exenatide-treated DM2 subjects had an insulin secretory pattern similar to healthy subjects in both first (0-10 min) and second (10-180 min) phases after glucose challenge, in contrast to saline-treated DM2 subjects. In exenatide-treated DM2 subjects, the most common adverse event was moderate nausea (two of 13 subjects). CONCLUSIONS: Short-term exposure to exenatide can restore the insulin secretory pattern in response to acute rises in glucose concentrations in DM2 patients who, in the absence of exenatide, do not display a first phase of insulin secretion. Loss of first-phase insulin secretion in DM2 patients may be restored by treatment with exenatide.
Exenatide is an incretin mimetic. It improves glycaemic control via various glucoregulatory mechanisms, including glucose-dependent insulinotropism, suppression of inappropriately high glucagon levels, delayed gastric emptying and reduction of food intake. In three large, well designed, phase III trials in adults with type 2 diabetes mellitus and suboptimal glycaemic control despite treatment with metformin and/or a sulfonylurea, mean changes from baseline in glycosylated haemoglobin (HbA(1c)) significantly favoured subcutaneous exenatide 5 or 10microg twice daily over placebo after 30 weeks' treatment (primary endpoint). Relative to placebo, reductions from baseline in bodyweight were significantly greater with twice-daily exenatide 5microg (in two studies) or 10microg (in all three studies). Post hoc completer analyses revealed that the beneficial effects of exenatide on HbA(1c) and bodyweight were maintained for up to 82 weeks. Adjunctive therapy with subcutaneous exenatide 10microg twice daily improved glycaemic control to a similar extent as insulin glargine in patients with type 2 diabetes suboptimally controlled with metformin plus a sulfonylurea in a large, well designed, 26-week, phase III trial. Subcutaneous exenatide was generally well tolerated in patients with type 2 diabetes. The incidence of hypoglycaemia in patients receiving exenatide plus metformin was similar to that seen in placebo plus metformin recipients; however, in patients receiving a sulfonylurea (with or without metformin), the incidence of hypoglycaemia was numerically higher with exenatide than with placebo.